Abdominal Aortic Aneurysm as a Complex Multifactorial Disease: Interactions of Polymorphisms of Inflammatory Genes, Features of Autoimmunity, and Current Status of MMPs

Thymidine Phosphorylase Promotes Abdominal Aortic Aneurysm via VSMC Modulation and Matrix Remodeling in Mice and Humans

Background: Thymidine phosphorylase (TYMP) promotes platelet activation and thrombosis while suppressing vascular smooth muscle cell (VSMC) proliferation. Both processes are central to the development and progression of abdominal aortic aneurysms (AAAs). We hypothesize that TYMP plays a role in AAA development. Methods: Male wild-type (WT) C57BL/6J and Tymp-/- mice, fed a Western diet (WD) (TD.88137), were subjected to the 4-week Ang II infusion-induced AAA model. AAA progression was monitored by echography and confirmed through necropsy. Whole-body inflammation was assessed using a plasma cytokine array. Mechanistic studies were conducted using TYMP-overexpressing rat VSMC cell lines and primary VSMCs cultured from WT and Tymp-/- mouse thoracic aortas. Histological studies were performed on human AAA and normal aorta samples. Results: Elevated TYMP levels were observed in human AAA vessel walls. While WT mice exhibited a 28.6% prevalence of Ang II infusion-induced AAA formation, Tymp-/- mice were protected. TYMP enhanced MMP2 expression, secretion, and activation in VSMCs, which was inhibited by tipiracil, a selective TYMP inhibitor. Systemically, TYMP promoted proinflammatory cytokine expression, and its absence attenuated TNF-α-induced MMP2 and AKT activation. WT VSMCs treated with platelets lacking TYMP showed a higher proliferation rate than cells treated with WT platelets. Additionally, TYMP increased activated TGFβ1 expression in cultured VSMCs and human AAA vessel walls. In WT VSMCs, TYMP augmented thrombospondin-1 type 1 repeat domain (TSR)-stimulated TGFβ1 signaling, increasing connective tissue growth factor and MMP2 production. TSR also enhanced AKT activation in WT VSMCs but had the opposite effect in Tymp-/- cells. TSR-enhanced MMP2 activation in WT VSMCs was attenuated by LY294002 (a PI3K inhibitor) but not by SB431542 (a TGFβ1 inhibitor); both inhibitors had indiscernible effects on Tymp-/- VSMC. Conclusion: TYMP emerges as a novel regulatory force in vascular biology, influencing VSMC function and inflammatory responses to promote AAA development.

Targeting extracellular matrix stiffness for cancer therapy

The physical characteristics of the tumor microenvironment (TME) include solid stress, interstitial fluid pressure, tissue stiffness and microarchitecture. Among them, abnormal changes in tissue stiffness hinder drug delivery, inhibit infiltration of immune killer cells to the tumor site, and contribute to tumor resistance to immunotherapy. Therefore, targeting tissue stiffness to increase the infiltration of drugs and immune cells can offer a powerful support and opportunities to improve the immunotherapy efficacy in solid tumors. In this review, we discuss the mechanical properties of tumors, the impact of a stiff TME on tumor cells and immune cells, and the strategies to modulate tumor mechanics.

The role of integrin-related genes in atherosclerosis complicated by abdominal aortic aneurysm

Increasingly, the shared risk factors and pathological processes of atherosclerosis and abdominal aortic aneurysm (AAA) are being recognized. The aim of our study was to identify the hub genes involved in the pathogenesis of atherosclerosis and AAA. The analysis was based on 2 gene expression profiles for atherosclerosis (GSE28829) and AAA (GSE7084), downloaded from the Gene Expression Omnibus database. Common differential genes were identified and an enrichment analysis of differential genes was conducted, with construction of protein-protein interaction networks, and identification of common hub genes, and predicted transcription factors. The analysis identified 133 differentially expressed genes (116 upregulated and 17 downregulated), with the enrichment analysis identifying a potential important role of integrins and chemokines in the common immune and inflammatory responses of atherosclerosis and AAA. Regulation of the complement and coagulation cascades and regulation of the actin cytoskeleton were associated with both diseases, with 10 important hub genes identified: TYROBP, PTPRC, integrin subunit beta 2, ITGAM, PLEK, cathepsin S, lymphocyte antigen 86, ITGAX, CCL4, and FCER1G. Findings identified a common pathogenetic pathway between atherosclerosis and AAA, with integrin-related genes playing a significant role. The common pathways and hub genes identified provide new insights into the shared mechanisms of these 2 diseases and can contribute to identifying new therapeutic targets and predicting the therapeutic effect of biological agents.

Comparative Analysis of Micro-Computed Tomography and 3D Micro-Ultrasound for Measurement of the Mouse Aorta

Aortic aneurysms, life-threatening and often undetected until they cause sudden death, occur when the aorta dilates beyond 1.5 times its normal size. This study used ultrasound scans and micro-computed tomography to monitor and measure aortic volume in preclinical settings, comparing it to the well-established measurement using ultrasound scans. The reproducibility of measurements was also examined for intra- and inter-observer variability, with both modalities used on 8-week-old C57BL6 mice. For inter-observer variability, the μCT (micro-computed tomography) measurements for the thoracic, abdominal, and whole aorta between observers were highly consistent, showing a strong positive correlation (R2 = 0.80, 0.80, 0.95, respectively) and no significant variability (p-value: 0.03, 0.03, 0.004, respectively). The intra-observer variability for thoracic, abdominal, and whole aorta scans demonstrated a significant positive correlation (R2 = 0.99, 0.96, 0.87, respectively) and low variability (p-values = 0.0004, 0.002, 0.01, respectively). The comparison between μCT and USS (ultrasound) in the suprarenal and infrarenal aorta showed no significant difference (p-value = 0.20 and 0.21, respectively). μCT provided significantly higher aortic volume measurements compared to USS. The reproducibility of USS and μCT measurements was consistent, showing minimal variance among observers. These findings suggest that μCT is a reliable alternative for comprehensive aortic phenotyping, consistent with clinical findings in human data.

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Thymidine Phosphorylase Promotes the Formation of Abdominal Aortic Aneurysm in Mice Fed a Western Diet

Aims

The precise molecular drivers of abdominal aortic aneurysm (AAA) remain unclear. Thymidine phosphorylase (TYMP) contributes to increased platelet activation, thrombosis, and inflammation, all of which are key factors in AAA development. Additionally, TYMP suppresses the proliferation of vascular smooth muscle cells (VSMCs), which are central to the development and progression of AAA. We hypothesize that TYMP plays a key role in AAA development.

Methods and Results

We conducted a histological study using human AAA samples and normal abdominal aortas, revealing heightened levels of TYMP in human AAA vessel walls. To validate this observation, we utilized an Ang II perfusion-induced AAA model in wild-type C57BL/6J (WT) and Tymp-/- mice, feeding them a Western diet (TD.88137) starting from 4 weeks of age. We found that Tymp-/- mice were protected from Ang II perfusion-induced AAA formation. Furthermore, by using TYMP-expressing VSMCs as well as primarily cultured VSMCs from WT and Tymp-/- mice, we elucidated the essential role of TYMP in regulating MMP2 expression and activation. TYMP deficiency or inhibition by tipiracil, a selective TYMP inhibitor, led to reduced MMP2 production, release, and activation in VSMCs. Additionally, TYMP was found to promote pro-inflammatory cytokine expression systemically, and its absence attenuates TNF-α-stimulated activation of MMP2 and AKT. By co-culturing VSMCs and platelets, we observed that TYMP-deficient platelets had a reduced inhibitory effect on VSMC proliferation compared to WT platelets. Moreover, TYMP appeared to enhance the expression of activated TGFβ1 in cultured VSMCs in vitro and in human AAA vessel walls in vivo. TYMP also boosted the activation of thrombospondin-1 type 1 repeat domain-enhanced TGFβ1 signaling, resulting in increased connective tissue growth factor production.

Conclusion

Our findings collectively demonstrated that TYMP serves as a novel regulatory force in vascular biology, exerting influence over VSMC functionality and inflammatory responses that promote the development of AAA.

Status of diagnosis and therapy of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are characterized by localized dilation of the abdominal aorta. They are associated with several serious consequences, including compression of adjacent abdominal organs, pain, treatment-related financial expenditure. The main complication of AAA is aortic rupture, which is responsible for about 200,000 deaths per year worldwide. An increasing number of researchers are dedicating their efforts to study AAA, resulting in significant progress in this field. Despite the commendable progress made thus far, there remains a lack of established methods to effectively decelerate the dilation of aneurysms. Therefore, further studies are imperative to expand our understanding and enhance our knowledge concerning AAAs. Although numerous factors are known to be associated with the occurrence and progression of AAA, the exact pathway of development remains unclear. While asymptomatic at most times, AAA features a highly unpredictable disease course, which could culminate in the highly deadly rupture of the aneurysmal aorta. Current guidelines recommend watchful waiting and lifestyle adjustment for smaller, slow-growing aneurysms, while elective/prophylactic surgical repairs including open repair and endovascular aneurysm repair are recommended for larger aneurysms that have grown beyond certain thresholds (55 mm for males and 50 mm for females). The latter is a minimally invasive procedure and is widely believed to be suited for patients with a poor general condition. However, several concerns have recently been raised regarding the postoperative complications and possible loss of associated survival benefits on it. In this review, we aimed to highlight the current status of diagnosis and treatment of AAA by an in-depth analysis of the findings from literatures.

SOMAscan Proteomics Identifies Novel Plasma Proteins in Amyotrophic Lateral Sclerosis Patients

Amyotrophic lateral sclerosis (ALS) is a complex disease characterized by the interplay of genetic and environmental factors for which, despite decades of intense research, diagnosis remains rather delayed, and most therapeutic options fail. Therefore, unravelling other potential pathogenetic mechanisms and searching for reliable markers are high priorities. In the present study, we employ the SOMAscan assay, an aptamer-based proteomic technology, to determine the circulating proteomic profile of ALS patients. The expression levels of ~1300 proteins were assessed in plasma, and 42 proteins with statistically significant differential expression between ALS patients and healthy controls were identified. Among these, four were upregulated proteins, Thymus- and activation-regulated chemokine, metalloproteinase inhibitor 3 and nidogen 1 and 2 were selected and validated by enzyme-linked immunosorbent assays in an overlapping cohort of patients. Following statistical analyses, different expression patterns of these proteins were observed in the familial and sporadic ALS patients. The proteins identified in this study might provide insight into ALS pathogenesis and represent potential candidates to develop novel targeted therapies.

How vascular smooth muscle cell phenotype switching contributes to vascular disease

Vascular smooth muscle cells (VSMCs) are the most abundant cell in vessels. Earlier experiments have found that VSMCs possess high plasticity. Vascular injury stimulates VSMCs to switch into a dedifferentiated type, also known as synthetic VSMCs, with a high migration and proliferation capacity for repairing vascular injury. In recent years, largely owing to rapid technological advances in single-cell sequencing and cell-lineage tracing techniques, multiple VSMCs phenotypes have been uncovered in vascular aging, atherosclerosis (AS), aortic aneurysm (AA), etc. These VSMCs all down-regulate contractile proteins such as α-SMA and calponin1, and obtain specific markers and similar cellular functions of osteoblast, fibroblast, macrophage, and mesenchymal cells. This highly plastic phenotype transformation is regulated by a complex network consisting of circulating plasma substances, transcription factors, growth factors, inflammatory factors, non-coding RNAs, integrin family, and Notch pathway. This review focuses on phenotypic characteristics, molecular profile and the functional role of VSMCs phenotype landscape; the molecular mechanism regulating VSMCs phenotype switching; and the contribution of VSMCs phenotype switching to vascular aging, AS, and AA. Video Abstract.

Inflammation-mediated matrix remodeling of extracellular matrix-mimicking biomaterials in tissue engineering and regenerative medicine

Extracellular matrix (ECM)-mimicking biomaterials are considered effective tissue-engineered scaffolds for regenerative medicine because of their biocompatibility, biodegradability, and bioactivity. ECM-mimicking biomaterials preserve natural microstructures and matrix-related bioactive components and undergo continuous matrix remodeling upon transplantation. The interaction between host immune cells and transplanted ECM-mimicking biomaterials has attracted considerable attention in recent years. Transplantation of biomaterials may initiate injuries and early pro-inflammation reactions characterized by infiltration of neutrophils and M1 macrophages. Pro-inflammation reactions may lead to degradation of the transplanted biomaterial and drive the matrix into a fetal-like state. ECM degradation leads to the release of matrix-related bioactive components that act as signals for cell migration, proliferation, and differentiation. In late stages, pro-inflammatory cells fade away, and anti-inflammatory cells emerge, which involves macrophage polarization to the M2 phenotype and leukocyte activation to T helper 2 (Th2) cells. These anti-inflammatory cells interact with each other to facilitate matrix deposition and tissue reconstruction. Deposited ECM molecules serve as vital components of the mature tissue and influence tissue homeostasis. However, dysregulation of matrix remodeling results in several pathological conditions, such as aggressive inflammation, difficult healing, and non-functional fibrosis. In this review, we summarize the characteristics of inflammatory responses in matrix remodeling after transplantation of ECM-mimicking biomaterials. Additionally, we discuss the intrinsic linkages between matrix remodeling and tissue regeneration. STATEMENT OF SIGNIFICANCE: Extracellular matrix (ECM)-mimicking biomaterials are effectively used as scaffolds in tissue engineering and regenerative medicine. However, dysregulation of matrix remodeling can cause various pathological conditions. Here, the review describes the characteristics of inflammatory responses in matrix remodeling after transplantation of ECM-mimicking biomaterials. Additionally, we discuss the intrinsic linkages between matrix remodeling and tissue regeneration. We believe that understanding host immune responses to matrix remodeling of transplanted biomaterials is important for directing effective tissue regeneration of ECM-mimicking biomaterials. Considering the close relationship between immune response and matrix remodeling results, we highlight the need for studies of the effects of clinical characteristics on matrix remodeling of transplanted biomaterials.

Adventitial Fibroblasts in Aortic Aneurysm: Unraveling Pathogenic Contributions to Vascular Disease

Aortic aneurysm (AA) is a degenerative vascular disease that involves aortic dilatation, and, if untreated, it can lead to rupture. Despite its significant impact on the healthcare system, its multifactorial nature and elusive pathophysiology contribute to limited therapeutic interventions that prevent the progression of AA. Thus, further research into the mechanisms underlying AA is paramount. Adventitial fibroblasts are one of the key constituents of the aortic wall, and they play an essential role in maintaining vessel structure and function. However, adventitial fibroblasts remain understudied when compared with endothelial cells and smooth muscle cells. Adventitial fibroblasts facilitate the production of extracellular matrix (ECM), providing structural integrity. However, during biomechanical stress and/or injury, adventitial fibroblasts can be activated into myofibroblasts, which move to the site of injury and secrete collagen and cytokines, thereby enhancing the inflammatory response. The overactivation or persistence of myofibroblasts has been shown to initiate pathological vascular remodeling. Therefore, understanding the underlying mechanisms involved in the activation of fibroblasts and in regulating myofibroblast activation may provide a potential therapeutic target to prevent or delay the progression of AA. This review discusses mechanistic insights into myofibroblast activation and associated vascular remodeling, thus illustrating the contribution of fibroblasts to the pathogenesis of AA.

The Role of ADAMTS-4 in Atherosclerosis and Vessel Wall Abnormalities

Extracellular matrix proteins are regulated by metzincin proteases, like the disintegrin metalloproteinases with thrombospondin motifs (ADAMTS) family members. This review focuses on the emerging role which ADAMTS-4 might play in vascular pathology, which has implications for atherosclerosis and vessel wall abnormalities, as well as for the resulting diseases, such as cardiovascular and cerebrovascular disease, aortic aneurysms, and dissections. Major substrates of ADAMTS-4 are proteoglycans expressed physiologically in smooth muscle cells of blood vessels. Good examples are versican and aggrecan, principal vessel wall proteoglycans that are targeted by ADAMTS-4, driving blood vessel atrophy, which is why this metzincin protease was implicated in the pathophysiology of vascular diseases with an atherosclerotic background. Despite emerging evidence, it is important not to exaggerate the role of ADAMTS-4 as it is likely only a small piece of the complex atherosclerosis puzzle and one that could be functionally redundant due to its high structural similarity to other ADAMTS family members. The therapeutic potential of inhibiting ADAMTS-4 to halt the progression of vascular disease after initialization of treatment is unlikely. However, it is not excluded that it might find a purpose as a biomarker of vascular disease, possibly as an indicator in a larger cytokine panel.

Associations of Genes for Killer Cell Immunoglobulin-like Receptors and Their Human Leukocyte Antigen-A/B/C Ligands with Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is an immune-mediated disease with a genetic component. The multifactorial pathophysiology is not clear and there is still no pharmacotherapy to slow the growth of aneurysms. The signal integration of cell-surface KIRs (killer cell immunoglobulin-like receptors) with HLA (ligands, human leukocyte class I antigen molecules) modulates the activity of natural killer immune cells. The genetic diversity of the KIR/HLA system is associated with the risk of immune disorders. This study was a multivariate analysis of the association between genetic variants of KIRs, HLA ligands, clinical data and AAA formation. Genotyping was performed by single polymerase chain reaction with sequence-specific primers using commercial assays. Patients with HLA-A-Bw4 have a larger aneurysm by an average of 4 mm (p = 0.008). We observed a relationship between aneurysm diameter and BMI in patients with AAA and co-existing CAD; its shape was determined by the presence of HLA-A-Bw4. There was also a nearly 10% difference in KIR3DL1 allele frequency between the study and control groups. High expression of the cell surface receptor KIR3DL1 may protect, to some extent, against AAA. The presence of HLA-A-Bw4 may affect the rate of aneurysm growth and represents a potential regional pathogenetic risk of autoimmune injury to the aneurysmal aorta.

Discovery of potential biomarkers for human atherosclerotic abdominal aortic aneurysm through untargeted metabolomics and transcriptomics

Abdominal aortic aneurysm (AAA) and atherosclerosis (AS) have considerable similarities in clinical risk factors and molecular pathogenesis. The aim of our study was to investigate the differences between AAA and AS from the perspective of metabolomics, and to explore the potential mechanisms of differential metabolites via integration analysis with transcriptomics. Plasma samples from 32 AAA and 32 AS patients were applied to characterize the metabolite profiles using untargeted liquid chromatography-mass spectrometry (LC-MS). A total of 18 remarkably different metabolites were identified, and a combination of seven metabolites could potentially serve as a biomarker to distinguish AAA and AS, with an area under the curve (AUC) of 0.93. Subsequently, we analyzed both the metabolomics and transcriptomics data and found that seven metabolites, especially 2'-deoxy-D-ribose (2dDR), were significantly correlated with differentially expressed genes. In conclusion, our study presents a comprehensive landscape of plasma metabolites in AAA and AS patients, and provides a research direction for pathogenetic mechanisms in atherosclerotic AAA.

Association of IL1R1 Coding Variant With Plasma-Level Soluble ST2 and Risk of Aortic Dissection

Objective: Aortic dissection (AD) is characterized by an acute onset, rapid progress, and high mortality. Levels of soluble ST2 (sST2) on presentation are elevated in patients with acute AD, which can be used to discriminate AD patients from patients with chest pain. sST2 concentrations were found to be highly heritable in the general population. The aim of this study was to investigate the associations of variations in ST2-related gene expression with sST2 concentrations and AD risk. Methods: This case-control study involving a total of 2,277 participants were conducted, including 435 AD patients and age- and sex-matched 435 controls in the discovery stage, and 464 patients and 943 controls in the validation stage. Eight ST2-related genes were selected by systematic review. Tag single-nucleotide polymorphisms (SNPs) were screened out from the Chinese population of the 1,000 Genomes Database. Twenty-one ST2-related SNPs were genotyped, and plasma sST2 concentrations were measured. Results: In the discovery stage, rs13019803 located in IL1R1 was significantly associated with AD after Bonferroni correction (p = 0.0009) and was correlated with circulating sST2 levels in patients with type A AD(AAD) [log-sST2 per C allele increased by 0.180 (95%) CI: 0.002 - 0.357] but not in type B. Combining the two stages together, rs13019803C was associated with plasma sST2 level in AAD patients [log-sST2 increased by 0.141 (95% CI: 0.055-0.227) for per C allele]. Odds ratio of rs13019803 on the risk of AAD is 1.67 (95% CI: 1.33-2.09). Conclusions: The IL1R1 SNP rs13019803C is associated with higher sST2 levels and increased risk of AAD.

Significance of Hemodynamics Biomarkers, Tissue Biomechanics and Numerical Simulations in the Pathogenesis of Ascending Thoracic Aortic Aneurysms

Guidelines for the treatment of aortic wall diseases are based on measurements of maximum aortic diameter. However, aortic rupture or dissections do occur for small aortic diameters. Growing scientific evidence underlines the importance of biomechanics and hemodynamics in aortic disease development and progression. Wall shear stress (WWS) is an important hemodynamics marker that depends on aortic wall morphology and on the aortic valve function. WSS could be helpful to interpret aortic wall remodeling and define personalized risk criteria. The complementarity of Computational Fluid Dynamics and 4D Magnetic Resonance Imaging as tools for WSS assessment is a promising reality. The potentiality of these innovative technologies will provide maps or atlases of hemodynamics biomarkers to predict aortic tissue dysfunction. Ongoing efforts should focus on the correlation between these non-invasive imaging biomarkers and clinico-pathologic situations for the implementation of personalized medicine in current clinical practice.

Chemerin-9 Attenuates Experimental Abdominal Aortic Aneurysm Formation in ApoE-/- Mice

Chronic inflammation plays an essential role in the pathogenesis of abdominal aortic aneurysm (AAA), a progressive segmental abdominal aortic dilation. Chemerin, a multifunctional adipocytokine, is mainly generated in the liver and adipose tissue. The combination of chemerin and chemokine-like receptor 1 (CMKLR1) has been demonstrated to promote the progression of atherosclerosis, arthritis diseases, and Crohn's disease. However, chemerin-9 acts as an analog of chemerin to exert an anti-inflammatory effect by binding to CMKLR1. Here, we first demonstrated that AAA exhibited higher levels of chemerin and CMKLR1 expression compared with the normal aortic tissues. Hence, we hypothesized that the chemerin/CMKLR1 axis might be involved in AAA progression. Moreover, we found that chemerin-9 treatment markedly suppressed inflammatory cell infiltration, neovascularization, and matrix metalloproteinase (MMP) expression, while increasing the elastic fibers and smooth muscle cells (SMCs) in Ang II-induced AAA in ApoE^-/- mice. This demonstrated that chemerin-9 could inhibit AAA formation. Collectively, our findings indicate a potential mechanism underlying AAA progression and suggest that chemerin-9 can be used therapeutically.

Mathematical model of atherosclerotic aneurysm

Atherosclerosis is a major cause of abdominal aortic aneurysm (AAA) and up to 80% of AAA patients have atherosclerosis. Therefore it is critical to understand the relationship and interactions between atherosclerosis and AAA to treat atherosclerotic aneurysm patients more effectively. In this paper, we develop a mathematical model to mimic the progression of atherosclerotic aneurysms by including both the multi-layer structured arterial wall and the pathophysiology of atherosclerotic aneurysms. The model is given by a system of partial differential equations with free boundaries. Our results reveal a 2D biomarker, the cholesterol ratio and DDR1 level, assessing the risk of atherosclerotic aneurysms. The efficacy of different treatment plans is also explored via our model and suggests that the dosage of anti-cholesterol drugs is significant to slow down the progression of atherosclerotic aneurysms while the additional anti-DDR1 injection can further reduce the risk.

Distribution and Dynamic Changes in Matrix Metalloproteinase (MMP)-2, MMP-9, and Collagen in an In Stent Restenosis Process

OBJECTIVE

The aim of this study was to observe the spatial distribution and dynamic changes of matrix metalloproteinase (MMP)-2, MMP-9, and collagen in in stent restenosis (ISR) and to explore their influence on ISR.

METHODS

Sixty Z type stents were implanted into the common iliac arteries of minipigs, which were divided into 10 groups (six in each group) according to euthanasia time (6 hours, and 1, 3, 7, 14, 28, 56, 84, 168, and 336 days). After the samples were harvested, haematoxylin and eosin staining, immunohistochemical staining, Western blotting, and Picrosirius red staining were performed for all groups.

RESULTS

ISR occurred in all six minipigs in the 56 day group (percentage diameter stenosis range 71.6%-79.2%, mean ± standard deviation 75.6% ± 2.5%). The percentage diameter stenosis decreased to 38.3% ± 2.7% at 336 days (p < .001). Immunohistochemical staining showed that MMP-2 and MMP-9 were strongly stained near the internal elastic lamina or in the damaged parts of the intima, around the struts and neointimal lumen surface in the ISR process. The expression of MMP-2 and MMP-9 at 56 days was significantly lower compared with their peaks (seven days and one day [p < .001; p = .002], respectively). At 56 days, the collagen content reached its maximum (mean integrated optical density range 0.73-0.92, mean ± standard deviation 0.82 ± 0.09). From the 14 day group to the 336 day group, mature collagen in neointima was correlated negatively with MMP-2 (γ(36) = -0.816; p < .001) and MMP-9 expression (γ(36) = -0.853; p < .001). During the neointimal regression period, new collagen in neointima was positively correlated with MMP-2 (γ(24) = 0.683; p < .001) and MMP-9 (γ(24) = 0.873; p < .001).

CONCLUSION

This study has demonstrated the spatial distribution of and dynamic changes in MMP-2, MMP-9, and collagen in ISR by simulating the process of neointima from generation to regression after stent implantation. When ISR occurred, MMP-2 and MMP-9 expression decreased and collagen content reached its maximum, which might contribute to ISR.

Relationships Between Perivascular Adipose Tissue and Abdominal Aortic Aneurysms

Abdominal aortic aneurysms (AAAs) are typically asymptomatic, and there is a high mortality rate associated with aneurysm rupture. AAA pathogenesis involves extracellular matrix degradation, vascular smooth muscle cell phenotype switching, inflammation, and oxidative stress. There is increasing evidence of excessive adipocyte accumulation in ruptured AAA walls. These excessive numbers of adipocytes in the vascular wall have been closely linked with AAA progression. Perivascular adipose tissue (PVAT), a unique type of adipose tissue, can be involved in adipocyte accumulation in the AAA wall. PVAT produces various chemokines and adipocytokines around vessels to maintain vascular homeostasis through paracrine and autocrine mechanisms in normal physiological conditions. Nevertheless, PVAT loses its normal function and promotes the progression of vascular diseases in pathological conditions. There is evidence of significantly reduced AAA diameter in vessel walls of removed PVAT. There is a need to highlight the critical roles of cytokines, cells, and microRNA derived from PVAT in the regulation of AAA development. PVAT may constitute an important therapeutic target for the prevention and treatment of AAAs. In this review, we discuss the relationship between PVAT and AAA development; we also highlight the potential for PVAT-derived factors to serve as a therapeutic target in the treatment of AAAs.

The association between simple renal cyst and aortic diseases: A systematic review and meta-analysis of observational studies

OBJECTIVE

The objective of this meta-analysis of observational studies was to evaluate the association between simple renal cysts (SRC) and presence of aortic pathology such as aortic aneurysms and dissection.

METHODS

We conducted searches in Ovid MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials from January 1960 to August 2019 to identify observational studies that examined the association between SRCs and any aortic diseases, including aortic aneurysms and dissection. Two reviewers independently extracted the data and assessed the risk of bias. The meta-analysis was performed by STATA 14.1.

RESULTS

In total, 11 observational studies with 19 719 participants were included in this meta-analysis. Compared to individuals without SRCs, patients with SRCs had higher odds of abdominal aortic aneurysm (AAA) (adjusted OR = 2.61, 95% CI 2.34-2.91, P < 0.001, I²   = 0%), ascending thoracic aortic aneurysm (TAA) (adjusted OR = 1.98, 95% CI 1.09-3.63, P = 0.03, I²   = 90.1%), descending TAA (adjusted OR = 3.44, 95% CI, 2.67-4.43, P < 0.001, I²   = 0%), type A aortic dissection (AD) (adjusted OR = 1.98, 95% CI 1.32-2.96, P = 0.001, I²   = 12.9%), and type B AD (adjusted OR = 2.55, 95% CI, 1.31-4.96, P = 0.006, I²   = 76.2%). There was a higher average in the sum of diameter of SRCs among AAA compared to patients without AAA (WMD = 19.80 mm, 95% CI 13.92-25.67, P < 0.001, I²   = 63.8%).

CONCLUSION

SRC is associated with higher odds of aortic diseases including AAA, ascending and descending TAA, type A and type B dissection even after adjusting for confounders.

Involvement of Matrix Metalloproteinase 9 in Vertebral Arterial Dissection With Posterior Circulation Ischemic Stroke

Background

Spontaneous vertebral arterial dissection (VAD) is an important cause of posterior circulation ischemic stroke (PCS), but its pathogenesis remains elusive. Matrix metalloproteinase 9 (MMP‐9) is a gelatinase involved in inflammation process and several vascular diseases, such as aorta dissection, but its role in VBD is unclear yet. The present study aimed to determine the association between serum MMP‐9 level and VAD‐related PCS.

Methods and Results

We recruited 149 patients with PCS, of which 30 were VAD and 119 had other determined etiologies (non‐VAD), and 219 non‐stroke individuals. Serum MMP‐9 was measured within 14 days from stroke onset. The age of VAD group was 59.6±15.0 years, which is similar to non‐stroke group (P=0.510) but significantly younger than non‐VAD group (69.9±14.0 years, P<0.001). Males and vascular risk factors were significantly more prevalent in VAD and non‐VAD groups than non‐stroke group (P<0.001). Multivariate logistic regression analysis adjusting potential confounders revealed that every 100 ng/mL of serum MMP‐9 level increment significantly predicted VAD (versus non‐stroke group: odds ratio (OR), 4.572; 95% CI, 2.240–9.333, P<0.001; versus non‐VAD group: OR, 1.819; 95% CI, 1.034–3.200, P=0.038).

Conclusions

Patients with VAD‐related PCS had higher levels of serum MMP‐9 at the acute stage of stroke compared with non‐stroke individuals and PCS of other causes, supporting the potential involvement of extracellular matrix‐degrading protease in the mechanism of VAD, which leads to ischemic events.

Role of matrix metalloproteinases in the pathogenesis of intracranial aneurysms

Intracranial aneurysms (IAs) are a result of complex interactions between biochemical and mechanical forces and can lead to significant morbidity if they rupture and cause subarachnoid hemorrhage. This review explores the role of matrix metalloproteinases (MMPs) in the pathogenesis and progression of IAs. In addition to providing a review of the normal function of MMPs, it is intended to explore the interaction between inflammation and abnormal blood flow and the resultant pathological vascular remodeling processes seen in the development and rupture of IAs. Also reviewed is the potential for the use of MMPs as a diagnostic tool for assessment of aneurysm development and progression.

Experimental abdominal aortic aneurysm growth is inhibited by blocking the JAK2/STAT3 pathway

BACKGROUND

The JAK/STAT pathway is a vital transcription signaling pathway that regulates gene expression and cellular activity. Our recently published study highlighted the role of IL-17A in abdominal aortic aneurysm (AAA) formation and rupture. IL-17A has been proven to upregulate vascular endothelial growth factor (VEGF) expression in some diseases. However, no study has demonstrated the relationships among JAK2/STAT3, IL-17A and VEGF. Therefore, we hypothesized that IL-17A may up-regulate VEGF expression via the JAK2/STAT3 signaling pathway to amplify the inflammatory response, exacerbate neovascularization, and accelerate AAA progression.

METHODS

To fully verify our hypothesis, two separate studies were performed: i) a study investigating the influence of JAK2/STAT3 on AAA formation and progression. ii) a study evaluating the relationship among IL-17A, JAK2/STAT3 and VEGF. Human tissues were collected from 7 AAA patients who underwent open surgery and 7 liver transplantation donors. All human aortic tissues were examined by histological and immunohistochemical staining, and Western blotting. Furthermore, mouse aortic tissues were also examined by histological and immunohistochemical staining and Western blotting, and the mouse aortic diameters were assessed by high-resolution Vevo 2100 microimaging system.

RESULTS

Among human aortic tissues, JAK2/STAT3, IL-17A and VEGF expression levels were higher in AAA tissues than in control tissues. Group treated with WP1066 (a selective JAK2/STAT3 pathway inhibitor), IL-17A, and VEGF groups had AAA incidences of 25%, 40%, and 65%, respectively, while the control group had an incidence of 75%. Histopathological analysis revealed that the IL-17A- and VEGF-related inflammatory responses were attenuated by WP1066. Thus, blocking the JAK2/STAT3 pathway with WP1066 attenuated experimental AAA progression. In addition, in study ii, we found that IL-17A siRNA seemed to attenuate the expression of IL-17A and VEGF in vivo study; treatment with VEGF siRNA decreased the expression of VEGF, while IL-17A expression remained high. In an in vitro study, rhIL-17A treatment increased JAK2/STAT3 and VEGF expression in macrophages in a dose-dependent manner.

CONCLUSION

Blocking the JAK2/STAT3 pathway with WP1066 (a JAK2/STAT3 specific inhibitor) attenuates experimental AAA progression. During AAA progression, IL-17A may influence the expression of VEGF via the JAK2/STAT3 signaling pathway. This potential mechanism may suggest a novel strategy for nonsurgical AAA treatment.

Interleukin-12 and -23 blockade mitigates elastase-induced abdominal aortic aneurysm

Macrophages play an important role in the inflammatory process that contributes to the development of abdominal aortic aneurysm (AAA). Studies of human and mouse AAA tissue reveal expanded populations of macrophages producing an abundance of pro-inflammatory cytokines, including TNF-α, IL-12p40 and high level of metalloprotease 9 (MMP-9) at the late stages of disease. Herein, we show that blockade of IL-12p40 in the early phase of aneurysm development suppresses macrophage expansion, inflammatory cytokine and MMP-9 production and mitigates AAA development. Since IL-12 and IL-23 are related cytokines that share the common p40 subunit, we also evaluate the effect of direct IL-23 blockade on the development of AAA. Specific IL-23p19 blockade prevents AAA progression with the same efficiency as IL-12p40 antagonism, suggesting that the efficacy of anti-IL-12p40 treatment may reflect IL-23 blockade. IL-12p40 and IL-23p19 are also abundantly expressed in human AAA tissue. Our findings have potential translational value since IL-12p40 and IL-23p19 antagonists already exist as FDA-approved therapeutics for various chronic inflammatory conditions.

The association between circulating endostatin levels and incident myocardial infarction

OBJECTIVE

Increased levels of circulating endostatin have been observed in patients with prevalent ischemic heart disease. However, the association between circulating endostatin, and incident myocardial infarction (MI) is less studied. Our main aim was to study the association between circulating endostatin and incident MI in the community adjusted for established cardiovascular risk factors in men and women.

DESIGN

Circulating endostatin was measured in a nested case control study based on three large community-based Swedish cohorts, including 533 MI cases, and 1003 age-, sex- and cohort-matched controls. Odds ratios (OR) with 95% confidence intervals (CI) were calculated with adjustments for established cardiovascular risk factors.

RESULTS

Higher endostatin was associated with a higher incidence of MI independently of established cardiovascular risk factors (OR 1.19, 95% CI 1.03-1.37, p = .02), but this association was abolished after additional adjustment for C-reactive protein. Sex-stratified analyses suggest that the association was substantially stronger in women as compared to men.

CONCLUSIONS

In our community based sample, higher endostatin predicted incident myocardial infarction predominantly in women but not independently of CRP. Thus, our findings do not support a broad utility of endostatin measurements for the prediction of incident myocardial infarction in clinical practice.

Incidence of Ventral Hernia Repair after Open Abdominal Aortic Aneurysm and Open Aortofemoral or Aortoiliac Bypass Surgery: An Analysis of 17,594 Patients in the State of New York

The purpose of our study was to evaluate the rate of ventral hernia repair (VHR) after open abdominal aortic anneurysm in New York State compared with the rate of VHR after open abdominal aortic bypass procedures. The Statewide Planning and Research Cooperative System database was queried for all abdominal aortic aneurysm (AAA) and bypass procedures performed between 2000 and 2010. Social security death index was used to identify patients who died. The cause-specific Cox proportional hazard model was applied to compare the risk of having follow-up VHR between patients with AAA and bypass with death as a competing risk event. A multivariable model was used to explore independent relationship with the risk of having follow-up ventral hernia after adjusting for other factors. There were 9314 patients who underwent open AAA repair, 739 (7.93%) of which had subsequent VHR. Comparatively, 8280 patients underwent aortofemoral or aortoiliac bypass procedures, with 480 (5.8%) undergoing subsequent VHR. The observed one-year, five-year, and 10-year VHR rates for AAA versus bypass were 2.8 versus 1.8 per cent, 10.0 versus 8.0 per cent, 10.7 versus 9.38 per cent, respectively. After controlling for all other factors, patients undergoing AAA repair were more likely and elderly patients were less likely to undergo VHR (P < 0.0001). Patients with serious comorbid conditions such as valvular disease, diabetes mellitus, and neurologic disorders were less likely to undergo subsequent VHR controlling for other factors. VHR after AAA procedures is more common compared with bypass procedures for occlusive disease. Because this patient population has significant comorbidity, prophylactic mesh placement may play a role in preventing necessity for future procedures.

Cytokine Profile of Human Abdominal Aortic Aneurysm: Involvement of JAK/STAT Pathway

Objective: Abdominal aortic aneurysm (AAA) is characterized by inflammation and destruction of normal tissue architecture. The present study aimed to evaluate the inflammatory signaling cascade by analyzing the cytokines of AAA tissue.

Materials and Methods: We analyzed the comprehensive cytokine secretion profiles of 52 cytokines from human AAA in four patients with AAA using fluorescent beads-based multiplex assay. Further, the effect of janus kinase (JAK) inhibition by pyridone 6 on cytokine profiles was also evaluated.

Results: Cytokine secretion profiles were found to be similar among the four patients. A high level of JAK/signal transducers and activator of transcription (STAT) pathway activity in AAA tissue in culture was maintained, which may be attributed to the secretion of endogenous JAK-activating cytokines. Inhibition of JAK by pyridone 6 resulted in the suppression of STAT3 phosphorylation and secretion of a subset of chemokines and JAK-activating cytokines. However, the inhibition of JAK had no effect on the secretion of matrix metalloproteinase (MMP)-2, MMP-9, or TGF-β family that is responsible for the metabolism of extracellular matrix.

Conclusion: The findings of the present study suggested that AAA tissue exhibits a stereotypical profile of cytokine secretion, where JAK/STAT pathway may play a role in regulating a subset of cytokines. Identification of such a cytokine profile may reveal potential diagnostic markers and therapeutic targets for AAA.

Matrix metalloproteinase family polymorphisms and the risk of aortic aneurysmal diseases: A systematic review and meta-analysis

It has been suggested that matrix metalloproteinase (MMP) polymorphisms are associated with the pathogenesis of aortic aneurysmal diseases. In this study, we conducted a systematic review with an update meta-analysis to investigate the relationship between MMP family polymorphisms and aortic aneurysmal diseases. We systematically reviewed 24 polymorphisms in 8 MMP genes related to the risk of abdominal aortic aneurysm (AAA), thoracic AA or thoracic aortic dissection (TAD). A total of 19 case-control studies with 15 highly studied MMP polymorphisms were included in our meta-analysis. Our results suggested that MMP2rs243865, MMP3rs3025058, MMP13rs2252070 polymorphisms were significantly associated with AAA risk, MMP2rs11643630, MMP8rs11225395 polymorphisms were correlated with TAD risk, and MMP9rs3918242 under the dominant model could increase AAA risk in hospital-based subgroup. No associations with aortic aneurysmal diseases were identified for other polymorphisms assessed in our meta-analysis. In summary, some studied MMP polymorphisms associated with the risk of aortic aneurysmal diseases are potential predictive biomarkers for the clinical application. Moreover, other MMP polymorphisms with limited studies but relevant to aortic aneurysmal formation and progression need further prospective and large investigations to confirm results.

MicroRNA-145 Mediates the Formation of Angiotensin II-Induced Murine Abdominal Aortic Aneurysm

BACKGROUND

MicroRNA-145 (miR-145) has been implicated in vascular smooth muscle cell differentiation, but the underlying mechanisms have not been fully understood, especially their role in abdominal aortic aneurysm (AAA) expansion. Here, we sought to explore and define the mechanisms of miR-145 function in the experimental AAA models in AngII-infused ApoE-/- mice.

METHODS

miR-145 was overexpressed in ApoE-/- mice via lentivirus infection, and then the incidence of AAA, maximum abdominal aortic diameter, elastin degradation and MMP2 activation were determined in AngII-infused ApoE-/- mice.

RESULTS

In vivo overexpression of miR-145 by lentivirus infection greatly decreased the incidence of AAA, maximum abdominal aortic diameter, and elastin degradation, accompanied with downregulation of MMP2 activation in AngII-infused ApoE-/- mice. Cell culture assays indicated that miR-145 inhibited AngII-induced upregulation of MMP2 gene expression. In contrast, deficiency of MMP2 abolished the effects of miR-145 on AngII-induced elastin and collagens degradations in ApoE-/- mice.

CONCLUSION

These data suggest that regulation of expression of miR-145 may be a potential therapeutic option for vascular disease progression such as AAA expansion.

Expression of a metalloproteinase family of ADAMTS in human vulnerable carotid lesions

AIMS

ADAMTS family of metalloproteases (a disintegrin and metalloprotease with thrombospondin motifs) possesses high proteolytic activity especially regarding proteoglycans. Their expression pattern in carotid plaques is as-yet unknown. The aim of the study was therefore the analysis of expression of ADAMTS1, 4, 5, and 13 and their inhibitors TIMP-1 and TIMP-3 in stable and unstable carotid plaques.

METHODS

Atherosclerotic plaques were collected from 40 patients (29 men, 11 women, mean age 70 years) undergoing carotid endarterectomy. The specimens were categorized into two groups (stable/unstable) according to Redgrave und Rothwell (The Oxford Plaque Study, 2008). SYBR Green-based real-time PCR, histology, and immunohistochemistry were performed.

RESULTS

All ADAMTS tested in our study were expressed in both stable and unstable plaques, especially in smooth muscle cells (SMCs) and macrophages. Analysis of the expression pattern on mRNA level showed significant higher expression of ADAMTS1 in unstable plaques compared with stable plaques (1.7-fold, P = 0.049). The expression of ADAMTS4 and 5 was also increased in unstable lesions; however, these changes were not statistically significant (1.2-fold, P = 0.667 and 1.6-fold, P = 0.077). Expression of TIMP-1 was significantly reduced in unstable plaques compared with stable ones (1.9-fold, P = 0.014).

CONCLUSION

SMCs seem to be an important source of ADAMTS analyzed in our study. Furthermore, expression of ADAMTS1 was found to be increased in unstable carotid lesions and might potentially contribute to plaque vulnerability.

Abdominal aortic aneurysm-an independent disease to atherosclerosis?

Atherosclerosis and abdominal aortic aneurysms (AAAs) are multifactorial and polygenic diseases with known environmental and genetic risk factors that contribute toward disease development. Atherosclerosis represents an important independent risk factor for AAA, as people with AAA often have atherosclerosis. Studies have shown that comorbidity is usually between ~25% and 55%, but it is still not fully known whether this association is causal or a result of common shared risk profiles. Most recent epidemiological, clinical, and biological evidence suggests that the two pathologies are more distinct than traditionally thought. For instance diabetes mellitus, hypercholesterolemia, and obesity are high risk for atherosclerosis development but are not as pronounced in AAA, whereas smoking, gender, and ethnicity are particularly high risk for AAA but less so for atherosclerosis. In addition, genetic and epigenetic studies have identified independent risk loci involved in AAA susceptibility that are not associated with other cardiovascular diseases, and research on important common cardiovascular biomarkers has illustrated discrepancies in those with AAA.

Differences in extracellular matrix proteins between Friesian horses with aortic rupture, unaffected Friesians and Warmblood horses

BACKGROUND

Unlike in Warmblood horses, aortic rupture is quite common in Friesian horses, in which a hereditary trait is suspected. The aortic connective tissue in affected Friesians shows histological changes such as medial necrosis, elastic fibre fragmentation, mucoid material accumulation and fibrosis with aberrant collagen morphology. However, ultrastructural examination of the collagen fibres of the mid-thoracic aorta has been inconclusive in further elucidating the pathogenesis of the disease.

OBJECTIVES

To assess several extracellular matrix (ECM) components biochemically in order to explore a possible underlying breed-related systemic ECM defect in Friesians with aortic rupture.

STUDY DESIGN

Cadaver study.

METHODS

Tissues from affected Friesians (n = 18), unaffected Friesians (n = 10) and Warmblood horses (n = 30) were compared. Samples were taken from the thoracic aorta at the level of the rupture site, from two locations caudal to the rupture and from the deep digital flexor tendon. Total collagen content, post-translational modifications of collagen formation including lysine hydroxylation, and hydroxylysylpyridinoline (HP), lysylpyridinoline (LP) and pyrrole cross-links were analysed. Additionally, elastin cross-links, glycosaminoglycan content and matrix metalloproteinase (MMP) activity were assessed.

RESULTS

Significantly increased MMP activity and increased LP and HP cross-linking, lysine hydroxylation and elastin cross-linking were found at the site of rupture in affected Friesians. These changes may reflect processes involved in healing and aneurysm formation. Unaffected Friesians had less lysine hydroxylation and pyrrole cross-linking within the tendons compared with Warmblood horses. No differences in the matrix of the aorta were found between normal Warmbloods and Friesian horses.

MAIN LIMITATIONS

Small sample size.

CONCLUSIONS

The differences in collagen parameters in tendon tissue may reflect differences in connective tissue metabolism between Friesians and Warmblood horses.

MicroRNAs Associated with Shoulder Tendon Matrisome Disorganization in Glenohumeral Arthritis

The extracellular matrix (ECM) provides core support which is essential for the cell and tissue architectural development. The role of ECM in many pathological conditions has been well established and ECM-related abnormalities leading to serious consequences have been identified. Though much has been explored in regards to the role of ECM in soft tissue associated pathologies, very little is known about its role in inflammatory disorders in tendon. In this study, we performed microRNA (miRNA) expression analysis in the long head of the human shoulder biceps tendon to identify key genes whose expression was altered during inflammation in patients with glenohumeral arthritis. We identified differential regulation of matrix metalloproteinases (MMPs) that could be critical in collagen type replacement during tendinopathy. The miRNA profiling showed consistent results between the groups and revealed significant changes in the expression of seven different miRNAs in the inflamed tendons. Interestingly, all of these seven miRNAs were previously reported to have either a direct or indirect role in regulating the ECM organization in other pathological disorders. In addition, these miRNAs were also found to alter the expression levels of MMPs, which are the key matrix degrading enzymes associated with ECM-related abnormalities and pathologies. To our knowledge, this is the first report which identifies specific miRNAs associated with inflammation and the matrix reorganization in the tendons. Furthermore, the findings also support the potential role of these miRNAs in altering the collagen type ratio in the tendons during inflammation which is accompanied with differential expression of MMPs.

Meta-Analysis of Genome-Wide Association Studies for Abdominal Aortic Aneurysm Identifies Four New Disease-Specific Risk Loci

Supplemental Digital Content is available in the text.

Rationale:

Abdominal aortic aneurysm (AAA) is a complex disease with both genetic and environmental risk factors. Together, 6 previously identified risk loci only explain a small proportion of the heritability of AAA.

Objective:

To identify additional AAA risk loci using data from all available genome-wide association studies.

Methods and Results:

Through a meta-analysis of 6 genome-wide association study data sets and a validation study totaling 10 204 cases and 107 766 controls, we identified 4 new AAA risk loci: 1q32.3 (SMYD2), 13q12.11 (LINC00540), 20q13.12 (near PCIF1/MMP9/ZNF335), and 21q22.2 (ERG). In various database searches, we observed no new associations between the lead AAA single nucleotide polymorphisms and coronary artery disease, blood pressure, lipids, or diabetes mellitus. Network analyses identified ERG, IL6R, and LDLR as modifiers of MMP9, with a direct interaction between ERG and MMP9.

Conclusions:

The 4 new risk loci for AAA seem to be specific for AAA compared with other cardiovascular diseases and related traits suggesting that traditional cardiovascular risk factor management may only have limited value in preventing the progression of aneurysmal disease.

Immunobiological factors aggravating the fatty infiltration on tendons and muscles in rotator cuff lesions

Rotator cuff lesions (RCLs) are a common cause of shoulder pain and dysfunction. The rotator cuff tendons can degenerate and/or tear from the greater tuberosity of the humerus, which is associated with several anatomical, physiological, biochemical, and molecular changes in tendon and muscle. In this article, these pathways are critically reviewed and discussed with various management strategies of RCLs. The article also highlights the immunobiological responses following the RCL and the inherent repair mechanisms elicited by the body. The greatest difficulty in treating this pathology is that the muscle can undergo irreversible fatty infiltration in the setting of chronic tears that is associated with poor surgical outcomes. The article also investigates the key molecular pathways of the muscle homeostasis (mTOR, Rho kinase, AMPK, and Ca(2+)) with the energy metabolism to propose a possible mechanism for fatty infiltration. Future research is warranted to target the key players of these pathways in the management of fatty infiltration and thus RCL.

Androgen receptor (AR) in cardiovascular diseases

Cardiovascular diseases (CVDs) are still the highest leading cause of death worldwide. Several risk factors have been linked to CVDs, including smoking, diabetes, hyperlipidemia, and gender among others. Sex hormones, especially the androgen and its receptor, androgen receptor (AR), have been linked to many diseases with a clear gender difference. Here, we summarize the effects of androgen/AR on CVDs, including hypertension, stroke, atherosclerosis, abdominal aortic aneurysm (AAA), myocardial hypertrophy, and heart failure, as well as the metabolic syndrome/diabetes and their impacts on CVDs. Androgen/AR signaling exacerbates hypertension, and anti-androgens may suppress hypertension. Androgen/AR signaling plays dual roles in strokes, depending on different kinds of factors; however, generally males have a higher incidence of strokes than females. Androgen and AR differentially modulate atherosclerosis. Androgen deficiency causes elevated lipid accumulation to enhance atherosclerosis; however, targeting AR in selective cells without altering serum androgen levels would suppress atherosclerosis progression. Androgen/AR signaling is crucial in AAA development and progression, and targeting androgen/AR profoundly restricts AAA progression. Men have increased cardiac hypertrophy compared with age-matched women that may be due to androgens. Finally, androgen/AR plays important roles in contributing to obesity and insulin/leptin resistance to increase the metabolic syndrome.

Abdominal aortic aneurysm and histological, clinical, radiological correlation

To date, the pathogenesis of abdominal aortic aneurism (AAA) still remains unclear. As such, the aim of this study was to evaluate changes of the aortic structure during AAA. We analysed the microscopic frame of vessels sections, starting from the primum movens leading to abnormal dilatation. AAA samples were collected and processed through various staining methods (Verhoeff-Van Gieson, Masson Goldner, Sirius Red). Subsequently, the vessel morphology and collagenic web of the tunica media and adventitia were determined and the amount of type I and type III collagen was measured. We also applied immune-histochemistry markers for CD34 and PGP 9.5 in order to identify vascular and nerve structures in the aorta. Immune-positivity quantification was used to calculate the percentage of the stained area. We found increasing deposition of type I collagen and reduced type III collagen in both tunica media and adventitia of AAA. The total amount of vasa vasorum, marked with CD34, and nerva vasorum, marked with PGP 9.5, was also higher in AAA samples. Cardiovascular risk factors (blood pressure, dyslipidemia, cigarette smoking) and radiological data (maximum aneurism diameter, intra-luminal thrombus, aortic wall calcification) increased these changes. These results suggest that the tunica adventitia may have a central role in the pathogenesis of AAA as clearly there are major changes characterized by rooted inflammatory infiltration. The presence of immune components could explain these modifications within the framework of the aorta.

Redox proteomic analysis of serum from aortic anerurysm patients: insights on oxidation of specific protein target

Oxidative stress is undoubtedly one of the main players in abdominal aortic aneurysm (AAA) pathophysiology.

LDL cholesterol and apolipoprotein B are associated with ascending aorta dilatation in bicuspid aortic valve patients

BACKGROUND

The factors related to ascending aorta dilation (AAD) in patients with bicuspid aortic valve (BAV) are not completely understood. In addition, the role of cholesterol metabolism in AAD has not been studied.

METHODS

We analyzed the relationship between different lipid parameters and the ascending aorta diameter/presence of aortic dilatation in 91 consecutive patients with BAV.

RESULTS

We observed a positive linear correlation between the total cholesterol, low-density lipoprotein (LDL) cholesterol and apolipoprotein B (ApoB) levels and the ascending aorta diameter. The patients with AAD had higher LDL cholesterol and ApoB levels. Whereas LDL cholesterol and ApoB were identified as independent factors predictors of the aortic root diameter, only ApoB predicted the diameter of the ascending aorta. On the other hand, the levels of ApoB were an independent factor related to the dilatation of the aortic root.

CONCLUSIONS

We have observed that cholesterol is associated with ascending aorta diameter and dilation in BAV patients. Further experimental and clinical studies are needed to explain the pathobiology of this association.

Structural analysis of adventitial collagen to feature aging and aneurysm formation in human aorta

OBJECTIVE

Adventitial collagen structure provides the aorta with tensile strength. Like other collagen-rich tissues, it can be affected by internal factors including aging and location. We determined whether the structural characteristics of human aortic adventitial collagen change with aging, location, and aneurysm formation.

METHODS

Nonatherosclerotic nonaneurysmal (NANA) human abdominal aortas were collected from 15 individuals who had died of noncardiovascular diseases (<40 years old, NANA young, n = 5; >60 years old, NANA old, n = 5). The architecture of adventitial collagen in the aortas was assessed by scanning electron microscopy, and fiber orientation was assessed by polarized microscopy with two-dimensional fast Fourier transform. We then analyzed retardation as an anisotropic property of adventitial collagen by polarized light microscopy. The orientation and retardation of NANA aortas were compared with those of abdominal aortic specimens from patients who were surgically treated for abdominal aortic aneurysm (AAA) (>60 years old, n = 11).

RESULTS

Adventitial collagen of the abdominal aortas on scanning electron microscopy images appeared as wavy, ropy fibers in aortas from young individuals (NANA young, n = 5) and were essentially flattened in those from older patents (NANA old, n = 5) and from those with AAA. Collagen fibers were thicker but sparser in the adventitia of aortas with AAA. Orientation maintained in the collagen fibers of NANA aortas (n = 15) on two-dimensional fast Fourier transform analysis was unrelated to either location or age and did not differ between NANA aortas and those with AAA. However, collagen fibrils in NANA aortas (n = 15) were significantly less retarded only at the level of the inferior mesenteric artery compared with other aortic locations. In addition, retardation was significantly reduced in abdominal aortas with AAA at the level of the inferior mesenteric artery.

CONCLUSIONS

The basic structure of adventitial collagen fiber was maintained in abdominal aortas regardless of location or age. Because the molecular structure at the subfibril level changed at abdominal aorta and enhanced in aortas with AAA, alterations in the molecular structure of adventitial collagen might be associated with aneurysmal formation.

Heat shock protein 90 inhibition by 17-DMAG attenuates abdominal aortic aneurysm formation in mice

Abdominal aortic aneurysm (AAA) is a common degenerative vascular disease whose pathogenesis is associated with activation of multiple signaling pathways including Jun NH2-terminal kinases (JNK) and NF-κB. It is now well recognized that these pathways are chaperoned by the heat shock protein 90 (Hsp90), suggesting that inhibition of Hsp90 may be a novel strategy for inhibiting AAAs. The aim of this study is to investigate whether inhibition of Hsp90 by 17-DMAG (17-dimethyl-aminothylamino-17-demethoxy-geldanamycin) attenuates ANG II-induced AAA formation in mice, and, if so, to elucidate the mechanisms involved. Apolipoprotein E-null mice were infused with ANG II to induce AAA formation and simultaneously treated by intraperitoneal injection with either vehicle or 17-DMAG for 4 wk. ANG II infusion induced AAA formation in 80% of mice, which was accompanied by increased matrix metalloproteinase (MMP) activity, enhanced tissue inflammation, oxidative stress, and neovascularization. Importantly, these effects were inhibited by 17-DMAG treatment. Mechanistically, we showed that 17-DMAG prevented the formation and progression of AAA through its inhibitory effects on diverse biological pathways including 1) by blocking ANG II-induced phosphorylation of ERK1/2 and JNK that are critically involved in the regulation of MMPs in vascular smooth muscle cells, 2) by inhibiting IκB kinase expression and expression of MCP-1, and 3) by attenuating ANG II-stimulated angiogenic processes critical to AAA formation. Our results demonstrate that inhibition of Hsp90 by 17-DMAG effectively attenuates ANG II-induced AAA formation by simultaneously inhibiting vascular inflammation, extracellular matrix degradation, and angiogenesis, which are critical in the formation and progression of AAAs.

Cigarette smoke-induced MMP2 and MMP9 secretion from aortic vascular smooth cells is mediated via the Jak/Stat pathway

It is hypothesized that cigarette smoke may increase MMP2 and MMP9 secretion through Jak/Stat pathway in the aorta, thereby facilitating abdominal aortic aneurysm (AAA) formation/progression in smokers. We observed through zymograms that treatment of male rat aortic vascular smooth muscle cells (RASMC) with an aqueous extract of cigarette smoke (CSE) for 24 hours resulted in a significant increase in pro-MMP9 (P = .005) and a modest increase in pro-MMP2 (P = .055) production. Western blot with protein extracts from CSE-treated RASMC showed up-regulation of pStat3, pJak2, and T-Jak2 and unchanged levels of T-Stat3. Transfection of RASMC with small interfering RNAs for Jak2, Stat3, or both Jak2 and Stat3 significantly reduced pro-MMP9 (P < .005) and pro-MMP2 (P < .05) in medium of CSE-treated RASMC compared with control small interfering RNA-transfected cells. Immunoprecipitation with total Jak2 antibody showed increased pStat3 and T-Stat3 in the cytoplasm and nucleus of CSE-treated RASMC. Immunofluorescence revealed increased presence of pJak2, T-Jak2, pStat3, and T-Stat3 in the cytoplasm and nucleus of the CSE-treated cells. Treatment of control human tissues with CSE resulted in pro-MMP9 secretion and up-regulation of the Jak/Stat proteins. In addition, AAA tissues showed more pJak2 and pStat3 than control human tissues. Therefore, inhibiting the Jak/Stat pathway could be a potential therapeutic approach in the treatment of AAA.

Degenerative disease in rotator cuff tears: what are the biochemical and histological changes?

The histopathological changes associated with rotator cuff tears include thinning and disorganization of collagen fibers, the presence of granulation tissue, increased levels of glycosaminoglycans, fibrocartilaginous metaplasia, calcification, fatty infiltration, and necrosis of the tendon margin with cell apoptosis. The biochemical changes include an increase in the expression of matrix metalloproteinases (MMPs) and a decrease in tissue inhibitor of metalloproteinases (TIMP) messenger ribonucleic acid expression. Histological evidence of tendinopathy has been found in patients with rotator cuff tear. Biochemical changes include significant increases in MMP1, MMP2, MMP3, and in TIMP1 and TIMP2 levels, not only at the lateral supraspinatus edge, but also in the macroscopically intact portion of the supraspinatus tendon and in the intact subscapularis. The tissue in the ruptured area of the supraspinatus tendon undergoes marked rearrangement at molecular levels. This involves the activity of MMP1, 2, and 3 and supports a critical role of MMPs in tendon physiology. Intact parts of the torn supraspinatus tendon can present the histopathological changes associated with rotator cuff tears. These findings suggest that biochemical changes can already occur in a macroscopically intact tendon and seem to point to a global degenerative process in the shoulder.

Spatiotemporal mapping of matrix remodelling and evidence of in situ elastogenesis in experimental abdominal aortic aneurysms

Spatiotemporal changes in the extracellular matrix (ECM) were studied within abdominal aortic aneurysms (AAAs) generated in rats via elastase infusion. At 7, 14 and 21 days post-induction, AAA tissues were divided into proximal, mid- and distal regions, based on their location relative to the renal arteries and the region of maximal aortic diameter. Wall thicknesses differed significantly between the AAA spatial regions, initially increasing due to positive matrix remodelling and then decreasing due to wall thinning and compaction of matrix as the disease progressed. Histological images analysed using custom segmentation tools indicated significant differences in ECM composition and structure vs healthy tissue, and in the extent and nature of matrix remodelling between the AAA spatial regions. Histology and immunofluorescence (IF) labelling provided evidence of neointimal AAA remodelling, characterized by presence of elastin-containing fibres. This remodelling was effected by smooth muscle α-actin-positive neointimal cells, which transmission electron microscopy (TEM) showed to differ morphologically from medial SMCs. TEM of the neointima further showed the presence of elongated deposits of amorphous elastin and the presence of nascent, but not mature, elastic fibres. These structures appeared to be deficient in at least one microfibrillar component, fibrillin-1, which is critical to mature elastic fibre assembly. The substantial production of elastin and elastic fibre-like structures that we observed in the AAA neointima, which was not observed elsewhere within AAA tissues, provides a unique opportunity to capitalize on this autoregenerative phenomenon and direct it from the standpoint of matrix organization towards restoring healthy aortic matrix structure, mechanics and function. Copyright © 2014 John Wiley & Sons, Ltd.