Sustained activation of ADP/P2ry12 signaling induces SMC senescence contributing to thoracic aortic aneurysm/dissection

Ciprofloxacin Accelerates Angiotensin-II-Induced Vascular Smooth Muscle Cells Senescence Through Modulating AMPK/ROS pathway in Aortic Aneurysm and Dissection

Aortic aneurysm and dissection (AAD) is a cardiovascular disease that poses a severe threat to life and has high morbidity and mortality rates. Clinical and animal-based studies have irrefutably shown that fluoroquinolones, a commonly prescribed antibiotic for treating infections, significantly increase the risk of AAD. Despite this, the precise mechanism by which fluoroquinolones cause AAD remains unclear. Therefore, this study aims to investigate the molecular mechanism and role of Ciprofloxacin definitively-a type of fluoroquinolone antibiotic-in the progression of AAD. Aortic transcriptome data were collected from GEO datasets to detect the genes and pathways expressed differently between healthy donors and AAD patients. Human primary Vascular Smooth Muscle Cells (VSMCs) were isolated from the aorta. After 72 h of exposure to 110ug/ml Ciprofloxacin or 100 nmol/L AngII, either or combined, the senescent cells were identified through SA-β-gal staining. MitoTracker staining was used to examine the morphology of mitochondria in each group. Cellular Reactive Oxygen Species (ROS) levels were measured using MitoSox and DCFH-DA staining. Western blot assay was performed to detect the protein expression level. We conducted an analysis of transcriptome data from both healthy donors and patients with AAD and found that there were significant changes in cellular senescence-related signaling pathways in the latter group. We then isolated and identified human primary VSMCs from healthy donors (control-VSMCs) and patients' (AAD-VSMCs) aortic tissue, respectively. We found that VSMCs from patients exhibited senescent phenotype as compared to control-VSMCs. The higher levels of p21 and p16 and elevated SA-β-gal activity demonstrated this. We also found that pretreatment with Ciprofloxacin promoted angiotensin-II-induced cellular senescence in control-VSMCs. This was evidenced by increased SA-β-gal activity, decreased cell proliferation, and elevation of p21 and p16 protein levels. Additionally, we found that Angiotensin-II (AngII) induced VSMC senescence by promoting ROS generation. We used DCFH-DA and mitoSOX staining to identify that Ciprofloxacin and AngII pretreatment further elevated ROS levels than the vehicle or alone group. Furthermore, JC-1 staining showed that mitochondrial membrane potential significantly declined in the Ciprofloxacin and AngII combination group compared to others. Compared to the other three groups, pretreatment of Ciprofloxacin plus AngII could further induce mitochondrial fission, demonstrated by mitoTracker staining and western blotting assay. Mechanistically, we found that Ciprofloxacin impaired the balance of mitochondrial fission and fusion dynamics in VSMCs by suppressing the phosphorylation of AMPK signaling. This caused mitochondrial dysfunction and ROS generation, thereby elevating AngII-induced cellular senescence. However, treatment with the AMPK activator partially alleviated those effects. Our data indicate that Ciprofloxacin may accelerate AngII-induced VSMC senescence through modulating AMPK/ROS signaling and, subsequently, hasten the progression of AAD.

Aging aggravates aortic aneurysm and dissection via miR-1204-MYLK signaling axis in mice

The mechanism by which aging induces aortic aneurysm and dissection (AAD) remains unclear. A total of 430 participants were recruited for the screening of differentially expressed plasma microRNAs (miRNAs). We found that miR-1204 is significantly increased in both the plasma and aorta of elder patients with AAD and is positively correlated with age. Cell senescence induces the expression of miR-1204 through p53 interaction with plasmacytoma variant translocation 1, and miR-1204 induces vascular smooth muscle cell (VSMC) senescence to form a positive feedback loop. Furthermore, miR-1204 aggravates angiotensin II-induced AAD formation, and inhibition of miR-1204 attenuates β-aminopropionitrile monofumarate-induced AAD development in mice. Mechanistically, miR-1204 directly targets myosin light chain kinase (MYLK), leading to the acquisition of a senescence-associated secretory phenotype (SASP) by VSMCs and loss of their contractile phenotype. MYLK overexpression reverses miR-1204-induced VSMC senescence, SASP and contractile phenotypic changes, and the decrease of transforming growth factor-β signaling pathway. Our findings suggest that aging aggravates AAD via the miR-1204-MYLK signaling axis.

Comprehensive analysis of gene signatures associated with aging in human aortic dissection

Background

Aortic dissection (AD) is a lethal aortic disease with limited effective therapeutic strategies. Aging increases the risk of AD, yet the underlying mechanisms remain unclear. This study aims to analyze the association of aging-related genes (Args) and AD using bioinformatic analysis. This helps provide novel insights into AD pathogenesis and contributes to developing novel therapeutic strategies.

Methods

mRNA (GSE52093, GSE153434), miRNA (GSE98770) and single-cell RNA-sequencing (scRNA-seq, GSE213740) datasets of AD were downloaded from GEO database. Args were downloaded from Aging Atlas database. Differentially-expressed Args were determined by intersecting Args and differentially-expressed mRNAs of two mRNA datasets. Cytoscape was used to identify hub genes and construct hub gene regulatory networks related to miRNAs. Seurat and clusterProfiler R package were used for investigating expression patterns of hub genes at single-cell level, and functional analysis, respectively. To validate the cellular expression pattern of hub genes, the same analysis was applied to our own scRNA-seq data. Drugs targeting hub Args were determined using the DGIdb database.

Results

HGF, CXCL8, SERPINE1, HIF1A, TIMP1, ESR1 and PLAUR were identified as aging-related hub genes in AD. miR-221-3p was predicted to interact with ESR1. A decreased ESR1 expression in smooth muscle cell subpopulation 4 (SMC4) was observed in AD versus normal aortic tissues, which was validated by sequencing 197,605 aortic cells from 13 AD patients. Additionally, upregulated genes of SMC4 in AD tissues were enriched in the "cellular senescence" pathway. These data indicated that decreased ESR1 might promote SMC4 aging during AD formation. Eleven existing drugs targeting hub genes were identified, including ruxolitinib and filgrastim, which are associated with AD.

Conclusions

By sequencing transcriptomic data, this study revealed aging-related hub genes and regulatory network involved in AD formation. Additionally, this study proposed a noteworthy hypothesis that downregulated ESR1 may exacerbate AD by promoting SMC aging, which requires further investigation.

Nerve growth factor (Ngf) gene-driven semaphorin 3a (Sema3a) expression exacerbates thoracic aortic aneurysm dissection in mice

Thoracic aortic aneurysm and dissection (TAAD) is a life-threatening disease and currently there is no pharmacological therapy. Sympathetic nerve overactivity plays an important role in the development of TAAD. Sympathetic innervation is mainly controlled by nerve growth factor (NGF, a key neural chemoattractant) and semaphoring 3A (Sema3A, a key neural chemorepellent), while the roles of these two factors in aortic sympathetic innervation and especially TAAD are unknown. We hypothesized that genetically manipulating the NGF/Sema3A ratio by the Ngf -driven Sema3a expression approach may reduce aortic sympathetic nerve innervation and mitigate TAAD progression. A mouse strain of Ngf gene-driven Sema3a expression (namely NgfSema3a/Sema3a mouse) was established by inserting the 2A-Sema3A expression frame to the Ngf terminating codon using CRISPR/Cas9 technology. TAAD was induced by β-aminopropionitrile monofumarate (BAPN) both in NgfSema3a/Sema3a mice and wild type (WT) littermates. Contrary to our expectation, the BAPN-induced TAAD was severer in NgfSema3a/Sema3a mice than in wild-type (WT) mice. In addition, NgfSema3a/Sema3a mice showed higher aortic sympathetic innervation, inflammation and extracellular matrix degradation than the WT mice after BAPN treatment. The aortic vascular smooth muscle cells isolated from NgfSema3a/Sema3a mice and pretreated with BAPN in vivo for two weeks showed stronger capabilities of proliferation and migration than that from the WT mice. We conclude that the strategy of Ngf -driven Sema3a expression cannot suppress but worsens the BAPN-induced TAAD. By investigating the aortic phenotype of NgfSema3a/Sema3a mouse strain, we unexpectedly find a path to exacerbate BAPN-induced TAAD which might be useful in future TAAD studies.

Activation of the alternative complement pathway modulates inflammation in thoracic aortic aneurysm/dissection

Thoracic aortic aneurysm/dissection (TAAD) is a lethal vascular disease, and several pathological factors participate in aortic medial degeneration. We previously discovered that the complement C3a-C3aR axis in smooth muscle cells promotes the development of thoracic aortic dissection (TAD) through regulation of matrix metalloproteinase 2. However, discerning the specific complement pathway that is activated and elucidating how inflammation of the aortic wall is initiated remain unknown. We ascertained that the plasma levels of C3a and C5a were significantly elevated in patients with TAD and that the levels of C3a, C4a, and C5a were higher in acute TAD than in chronic TAD. We also confirmed the activation of the complement in a TAD mouse model. Subsequently, knocking out Cfb (Cfb) or C4 in mice with TAD revealed that the alternative pathway and Cfb played a significant role in the TAD process. Activation of the alternative pathway led to generation of the anaphylatoxins C3a and C5a, and knocking out their receptors reduced the recruitment of inflammatory cells to the aortic wall. Moreover, we used serum from wild-type mice or recombinant mice Cfb as an exogenous source of Cfb to treat Cfb KO mice and observed that it exacerbated the onset and rupture of TAD. Finally, we knocked out Cfb in the FBN1C1041G/+ Marfan-syndrome mice and showed that the occurrence of TAA was reduced. In summary, the alternative complement pathway promoted the development of TAAD by recruiting infiltrating inflammatory cells. Targeting the alternative pathway may thus constitute a strategy for preventing the development of TAAD.NEW & NOTEWORTHY The alternative complement pathway promoted the development of TAAD by recruiting infiltrating inflammatory cells. Targeting the alternative pathway may thus constitute a strategy for preventing the development of TAAD.

Targeting Vascular Smooth Muscle Cell Senescence: A Novel Strategy for Vascular Diseases

Vascular diseases are a major threat to human health, characterized by high rates of morbidity, mortality, and disability. VSMC senescence contributes to dramatic changes in vascular morphology, structure, and function. A growing number of studies suggest that VSMC senescence is an important pathophysiological mechanism for the development of vascular diseases, including pulmonary hypertension, atherosclerosis, aneurysm, and hypertension. This review summarizes the important role of VSMC senescence and senescence-associated secretory phenotype (SASP) secreted by senescent VSMCs in the pathophysiological process of vascular diseases. Meanwhile, it concludes the progress of antisenescence therapy targeting VSMC senescence or SASP, which provides new strategies for the prevention and treatment of vascular diseases.

Microvesicle-Mediated Tissue Regeneration Mitigates the Effects of Cellular Ageing

Extracellular vesicles (EVs), comprising microvesicles (MVs) and exosomes (Exos), are membranous vesicles secreted by cells which mediate the repair of cellular and tissue damage via paracrine mechanisms. The action of EVs under normative and morbid conditions in the context of ageing remains largely unexplored. We demonstrate that MVs, but not Exos, from Pathfinder cells (PCs), a putative stem cell regulatory cell type, enhance the repair of human dermal fibroblast (HDF) and mesenchymal stem cell (MSC) co-cultures, following both mechanical and genotoxic stress. Critically, this effect was found to be both cellular age and stress specific. Notably, MV treatment was unable to repair mechanical injury in older co-cultures but remained therapeutic following genotoxic stress. These observations were further confirmed in human dermal fibroblast (HDF) and vascular smooth muscle cell (VSMC) co-cultures of increasing cellular age. In a model of comorbidity comprising co-cultures of HDFs and highly senescent abdominal aortic aneurysm (AAA) VSMCs, MV administration appeared to be senotherapeutic, following both mechanical and genotoxic stress. Our data provide insights into EVs and the specific roles they play during tissue repair and ageing. These data will potentiate the development of novel cell-free therapeutic interventions capable of attenuating age-associated morbidities and avoiding undesired effects.

Bioinformatics analysis of aging-related genes in thoracic aortic aneurysm and dissection

Objective

Thoracic aortic aneurysm and dissection (TAAD) is a cardiovascular disease with a high mortality rate. Aging is an important risk factor for TAAD. This study explored the relationship between aging and TAAD and investigated the underlying mechanisms, which may contribute to the diagnosis and treatment of TAAD.

Methods

Human aging genes were obtained from the Aging Atlas official website. Various datasets were downloaded from the GEO database:the human TAAD dataset GSE52093 were used for screening differentially expressed genes (DEGs); GSE137869, GSE102397 and GSE153434 were used as validation sets, and GSE9106 was used for diagnostic prediction of receiver operating characteristic (ROC) curves. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Set Enrichment Analysis (GSEA), and protein-protein interaction (PPI) network analysis were used to screen differentially co-expressed genes from human aging genes and TAAD. Using five methods of the cytoHubba plugin in Cytoscape software (Degree, Closeness, EPC, MNC, Radiality), hub genes were identified from the differentially co-expressed genes. Single-cell RNA sequencing was used to verify the expression levels of hubgenes in different cell types of aortic tissue. ROC curves were used to further screen for diagnostic genes.

Results

A total of 70 differentially co-expressed genes were screened from human aging genes and DEGs in human TAAD dataset GSE52093. GO enrichment analysis revealed that the DEGs played a major role in regulating DNA metabolism and damaged DNA binding. KEGG enrichment analysis revealed enrichment in the longevity regulating pathway, cellular senescence, and HIF-1 signaling pathway. GSEA indicated that the DEGs were concentrated in the cell cycle and aging-related p53 signaling pathway. The five identified hubgenes were MYC, IL6, HIF1A, ESR1, and PTGS2. Single-cell sequencing of the aging rat aorta showed that hubgenes were expressed differently in different types of cells in aortic tissue. Among these five hubgenes, HIF1A and PTGS2 were validated in the aging dataset GSE102397; MYC, HIF1A and ESR1 were validated in the TAAD dataset GSE153434. The combined area under the diagnostic ROC curve (AUC) values for the five hub genes were >0.7 in the testing and training sets of the dataset GSE9106. The combined AUC values of MYC and ESR1 were equal to the combin ed AUC values of the five hub genes.

Conclusion

The HIF-1 signaling pathway may play an important role in TAAD and aging. MYC and ESR1 may have diagnostic value for aging-related TAAD.

Cellular senescence and abdominal aortic aneurysm: From pathogenesis to therapeutics

As China’s population enters the aging stage, the threat of abdominal aortic aneurysm (AAA) mainly in elderly patients is becoming more and more serious. It is of great clinical significance to study the pathogenesis of AAA and explore potential therapeutic targets. The purpose of this paper is to analyze the pathogenesis of AAA from the perspective of cellular senescence: on the basis of clear evidence of cellular senescence in aneurysm wall, we actively elucidate specific molecular and regulatory pathways, and to explore the targeted drugs related to senescence and senescent cells eliminate measures, eventually improve the health of patients with AAA and prolong the life of human beings.

Fibroblast-Secreted Phosphoprotein 1 Mediates Extracellular Matrix Deposition and Inhibits Smooth Muscle Cell Contractility in Marfan Syndrome Aortic Aneurysm

Fibrillin 1 (Fbn1) mutation causes Marfan syndrome (MFS) with thoracic aortic aneurysm (TAA) as the main complication. The mechanisms for extracellular matrix (ECM) homeostasis disruption in MFS TAA are unclear. Here, we found ECM-related gene secreted phosphoprotein 1 (Spp1) increased in Fbn1^C1041G/+ mice using transcriptome sequencing and a distinct fibroblast subcluster with Spp1 as the strongest marker was identified with analysis of the MFS mouse aortic single-cell sequencing dataset. Immunostaining confirmed elevated Spp1 in adventitial fibroblasts, and Spp1 might regulate fibroblast and smooth muscle cell (SMC) communication primarily through Itga8/Itgb1. Then, we observed Spp1 reduced contractile genes Acta2 and Tagln expression in SMCs and increased collagen expression in fibroblasts, which might contribute to TAA development. Finally, we also found elevated SPP1 plasma level was associated with an increased risk of TAA in patients. Therefore, SPP1 may serve as a biomarker and therapeutic target for TAA.

Trimethylamine N-Oxide Promotes Abdominal Aortic Aneurysm Formation by Aggravating Aortic Smooth Muscle Cell Senescence in Mice

Trimethylamine N-oxide (TMAO) has been linked to cardiovascular disease morbidity and mortality. However, the role of TMAO in the development of abdominal aortic aneurysms (AAAs) is not known. This study investigated the association between TMAO and AAA formation. TMAO and saline were added to the drinking water of angiotensin II (AngII)- and calcium chloride (CaCl₂)-induced AAA model mice, respectively. After 4 weeks, the effects of TMAO on AAA development were determined by histology and immunohistology of aortic tissue. The in vitro effects of TMAO were also examined in mouse aortic smooth muscle cells (SMCs). The maximal aortic diameter, incidence of AAA, and degree of elastin degradation were significantly increased in TMAO-treated mice. TMAO also increased the accumulation of the senescence markers p21 and p16, as well as of reactive oxygen species (ROS), matrix metalloproteinase-2 (MMP2), and matrix metalloproteinase-9 (MMP9) in vivo and in vitro. TMAO promoted AAA development in mouse AAA models induced by AngII and CaCl₂ by a mechanism involving cellular senescence.

β-Aminopropionitrile-induced aortic aneurysm and dissection in mice

The mechanistic basis for the formation of aortic aneurysms and dissection needs to be elucidated to facilitate the development of effective medications. β-Aminopropionitrile administration in mice has been used frequently to study the pathologic features and mechanisms of aortic aneurysm and dissection. This mouse model mimics several facets of the pathology of human aortic aneurysms and dissection, although many variables exist in the experimental design and protocols that must be resolved to determine its application to the human disease. In the present brief review, we have introduced the development of this mouse model and provided insights into understanding its pathologic features.

The Role and Molecular Mechanism of P2Y12 Receptors in the Pathogenesis of Atherosclerotic Cardiovascular Diseases

The P2Y receptor family is a class of G protein-coupled receptors activated primarily by adenosine triphosphate (ATP), adenosine diphosphate (ADP), uridine triphosphate (UTP) and uridine diphosphate (UDP). The P2Y12 receptor is expressed on platelets which mediates platelet aggregation and morphological changes. At the same time, during the process of vascular remodeling and atherosclerosis, ADP can also promote the migration and proliferation of vascular smooth muscle and endothelial cells through P2Y12 receptor activating. Furthermore, P2Y12 is involved in many signal transductions processes, such as intimal hyperplasia, monocyte infiltration and so on, which play an important role in immune inflammation and brain injury. In order to solve the diseases induced by P2Y12 receptor, inhibitors such as ticagrelor, clopidogrel were widely used for cardiovascular diseases. However, there were some problems, such as limited antithrombotic effect, remain unsolved. This article summarizes the role and molecular mechanism of P2Y12 receptors in the pathogenesis of cardiovascular-related diseases, providing in-depth expounding on the molecular mechanism of P2Y12 receptor inhibitors and contributing to the treatment of diseases based on P2Y12 receptors.

Excessive mechanical stretch‑mediated osteoblasts promote the catabolism and apoptosis of chondrocytes via the Wnt/β‑catenin signaling pathway

Excessive biomechanical loading is considered an important cause of osteoarthritis. Although the mechanical responses of chondrocytes and osteoblasts have been investigated, their communication during mechanical loading and the underlying molecular mechanisms are not yet fully known. The present study investigated the effects of excessive mechanically stretched osteoblasts on the metabolism and apoptosis of chondrocytes, and also assessed the involvement of the Wnt/β‑catenin signaling pathway. In the present study, rat chondrocytes and osteoblasts were subjected to mechanical tensile strain, and an indirect chondrocyte‑osteoblast co‑culture model was established. Reverse transcription‑quantitative PCR and western blotting were performed to determine the expression levels of genes and proteins of interest. An ELISA was performed to investigate the levels of cytokines, including matrix metalloproteinase (MMP) 13, MMP 3, interleukin‑6 (IL‑6) and prostaglandin E2 (PG E2), released from osteoblasts. Flow cytometry was performed to detect the apoptosis of chondrocytes exposed to stretched osteoblast conditioned culture medium. The levels of MMP 13, IL‑6 and PG E2 increased significantly in the supernatants of stretched osteoblasts compared with the un‑stretched group. By contrast, the mRNA expression levels of Collagen 1a and alkaline phosphatase were significantly decreased in osteoblasts subjected to mechanical stretch compared with the un‑stretched group. The mRNA expression level of Collagen 2a was significantly decreased, whereas the expression levels of MMP 13 and a disintegrin and metalloproteinase with thrombospondin‑like motifs 5 were significantly increased in chondrocytes subjected to mechanical stretch compared with the un‑stretched group. In the co‑culture model, the results indicated that excessive mechanically stretched osteoblasts induced the catabolism and apoptosis of chondrocytes, which was partly inhibited by Wnt inhibitor XAV‑939. The results of the present study demonstrated that excessive mechanical stretch led to chondrocyte degradation and inhibited osteoblast osteogenic differentiation; furthermore, excessive mechanically stretched osteoblasts induced the catabolism and apoptosis of chondrocytes via the Wnt/β‑catenin signaling pathway.

BAPN-induced rodent model of aortic dissecting aneurysm and related complications

Background

The aim of this study was to investigate the effects of beta-aminopropionitrile (BAPN) on the arterial walls of rodents, and to analyze the gross or pathological changes of arterial and other tissues of rodents treated with BAPN at different concentrations or doses.

Methods

Eighteen SPF SD rats (4–5-week old) were divided into three groups: SD-0.2 (Group A), SD-0.4 (Group B), and SD-0.6 (Group C). The groups A, B and C were given 0.2%, 0.4%, and 0.6% BAPN solution, respectively, as drinking water for seven weeks. Forty SPF C57BL/6 mice (3-week old) were randomly divided into four groups: C57-0.2 (Group D), C57-0.4 (Group E), C57-0.6 (Group F) and the control group and given 0.2%, 0.4%, or 0.6% BAPN or distilled water as drinking water, respectively, for seven weeks. All experimental animals were free to drink water. The aortas were dissected and visually examined. At the same time, hematoxylin and eosin (HE) staining was performed in aorta tissue. The vascular diameter and area of the middle membrane were measured with IPP (Image-Pro Plus 6.0).

Results

BAPN treatment significantly affected the water intake and weight gain of rats and mice. BAPN also caused thickening of the membrane in the aortas of rats and mice, and irregularity in the arrangement of elastic fibers. These pathological changes are similar to the pathological changes observed in human aneurysms. The incidence of dissecting aneurysm in C57 mice was higher than that of Sprague Dawley (SD) rats.

Conclusions

BAPN at a concentration of 0.4% was feasible to produce an animal model of dissecting aneurysm. In SD rats, the rate of pathological changes and other complications, such as intestinal rupture and scoliosis, was higher than the rates of dissecting aneurysm.

Weighted miRNA co-expression network reveals potential roles of apoptosis related pathways and crucial genes in thoracic aortic aneurysm

Background

Thoracic aortic aneurysm (TAA) is a potentially life-threatening disease for which few medical therapies are available. Thus, it is critically important to investigate the underlying molecular mechanisms of TAA, and identify potential targets for TAA treatment.

Methods

Differentially expressed miRNAs (DEMs) and differentially expressed genes (DEGs) were screened, and a weighted correlation network analysis (WGCNA) was employed to construct a weighted miRNA co-expression network using GSE110527. The DEMs were then mapped into the whole co-expression network of all samples, and a DEM coexpression network was created. Molecular Complex Detection (MCODE) was used to identify crucial miRNAs. Target genes were predicted using the miRTarbase database, and further screened by identifying genes that overlapped with the DEGs of GSE26155. The screened target genes were validated using GSE9106, and the successfully validated genes were considered as crucial genes. Finally, a miRNA risk score for diagnosing TAA was calculated by undertaking a least absolute shrinkage and selection operator (LASSO) regression.

Results

The tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) signaling pathway was found in DEM functional enrichment. Crucial miRNAs were identified and target genes were predicted and associated with the regulation of the TRAIL signaling pathway. Next, 113 important target genes were identified as overlapping with the DEGs of GSE26155. These genes were further validated, and 5 successfully validated genes were considered as crucial genes. Finally, the miRNA risk score calculated by the LASSO regression was shown to have potential diagnostic value.

Conclusions

We performed a WGCNA analysis to construct a weighted miRNA co-expression network, predicted target genes of crucial miRNAs, identified crucial genes, and finally calculated a miRNA risk score. The results showed that pathways and genes associated with apoptosis appear to play an important role in TAA pathogenesis, and that medications targeting apoptosis might slow TAA progression. Future in vitro and in vivo experimental studies need to be undertaken to further validate our findings and investigate the mechanistic details of these crucial miRNAs and crucial genes.

Partial recovery of senescence in circulating follicular helper T cells after Dasatinib treatment

Cellular senescence is an irreversible arrest of cell proliferation triggered by different stimuli, including DNA damage, telomere shortening and oncogenic stress. Senescent cells, by releasing the senescence-associated-secretory-phenotype (SASP), contribute to various diseases pathogenesis. Human atherosclerotic plaque contains cells with multiple markers of senescence that associate with disease severity. We characterized the frequency of senescent cTfh cells and genes expressions before and after treatment with Dasatinib in patients with different degrees of stenosis. Twelve high (≥50%), and twelve low (<50%) stenosis patients and six healthy controls were enrolled. The percentage of senescent CD3⁺CD4⁺CXCR5⁺CD153⁺CD57⁺ cells was significantly decreased in Dasatinib treated cells from individuals with low and high stenosis (P = 0.0007 and P = 0.0002, respectively). However, the frequency of total lymphocytes, CD3⁺ and CD4⁺ T cells were not significantly different between the groups before and after treatment. The expression levels of P53 (P = 0.0003 and P = 0.0001), P16 (P = 0.0005 and P = 0.0002), p21 (P = 0.0002 and P < 0.0001), SENEX (P = 0.0005 and P < 0.0001) and BCL-2 (P = 0.0005 and P = 0.0002) were decreased in PBMCs of low and high stenosis groups after treatment with Dasatinib, respectively. The percentage of senescent cTfh cells positively correlated with cholesterol (P = 0.034; r = 0.671), C-reactive protein (CRP) (P = 0.029; r = 0.707), Erythrocyte sedimentation rate (ESR) levels (P = 0.030; r = 0.598) and neutrophil counts (P = 0.021; r = 0.799) in patients with high stenosis. The decreased frequency of senescent cTfh cells and the expression levels of senescence genes after Dasatinib treatment in patients with atherosclerosis suggest a role for Dasatinib in partial clearance or rejuvenation of senescent cTfh cells, which may decrease inflammatory mediators and attenuate disease progression.

MKL1 cooperates with p38MAPK to promote vascular senescence, inflammation, and abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a catastrophic disease with little effective therapy. Myocardin related transcription factor A (MRTFA, MKL1) is a multifaceted transcription factor, regulating diverse biological processes. However, a detailed understanding of the mechanistic role of MKL1 in AAA has yet to be elucidated. In this study, we showed induced MKL1 expression in thoracic and abdominal aneurysmal tissues, respectively in both mice and humans. MKL1 global knockout mice displayed reduced AAA formation and aortic rupture compared with wild-type mice. Both gene deletion and pharmacological inhibition of MKL1 markedly protected mice from aortic dissection, an early event in Angiotensin II (Ang II)-induced AAA formation. Loss of MKL1 was accompanied by reduced senescence/proinflammation in the vessel wall and cultured vascular smooth muscle cells (VSMCs). Mechanistically, a deficiency in MKL1 abolished AAA-induced p38 mitogen activated protein kinase (p38MAPK) activity. Similar to MKL1, loss of MAPK14 (p38α), the dominant isoform of p38MAPK family in VSMCs suppressed Ang II-induced AAA formation, vascular inflammation, and senescence marker expression. These results reveal a molecular pathway of AAA formation involving MKL1/p38MAPK stimulation and a VSMC senescent/proinflammatory phenotype. These data support targeting MKL1/p38MAPK pathway as a potential effective treatment for AAA.

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MKL1 expression is induced in both thoracic and abdominal aneurysmal tissues.

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Genetic ablation and pharmacological inhibition of MKL1 protect mice from aortic dissection and AAA induced by Ang II.

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Depletion of MKL1 in mice suppresses Ang II-induced vascular inflammation and senescence.

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Depletion of MKL1 blunts the activation of p38MAPK and STAT3 pathways.

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Loss of MAPK14 in VSMCs suppresses Ang II-induced AAA formation, vascular inflammation, and senescence marker expression.

Substance P blocks β-aminopropionitrile-induced aortic injury through modulation of M2 monocyte-skewed monocytopoiesis

Aortic injuries, including aortic aneurysms and dissections, are fatal vascular diseases with distinct histopathological features in the aortic tissue such as inflammation-induced endothelial dysfunction, infiltration of immune cells, and breakdown of the extracellular matrix. Few treatments are available for treating aortic aneurysms and dissections; thus, basic and clinical studies worldwide have been attempted to inhibit disease progression. Substance P (SP) exerts anti-inflammatory effects and promotes restoration of the damaged endothelium, leading to vasculature protection and facilitation of tissue repair. This study was conducted to explore the protective effects of systemically injected SP on thoracic aortic injury (TAI). A TAI animal model was induced by orally administering β-aminopropionitrile to rats for 6 weeks. β-aminopropionitrile blocked crosslinking ECM in aorta to cause structural alteration with inflammation within 1 week and then, induced aortic dissection within 4 weeks of initiating treatment, leading to mortality within 6 weeks. Treatment of TAI rats with SP-induced anti-inflammatory responses systemically and locally, possibly by enriching anti-inflammatory M2 monocytes in the spleen and peripheral blood at early phase of aortic injury due to β-aminopropionitrile. SP-induced immune suppression finally prevented the development of aortic dissection by limiting inflammation-mediated aortic destruction. Taken together, these results suggest that SP treatment can block aortic injury by controlling the immune-cell profile and suppressing proinflammatory responses during the initial stage of vascular disease progression.

CircRNA-0077930 from hyperglycaemia-stimulated vascular endothelial cell exosomes regulates senescence in vascular smooth muscle cells

Vascular smooth muscle aging leads to diabetic complications such as cardiovascular and kidney diseases or diabetic foot. Therefore, understanding the mechanism of smooth muscle cell senescence in a high-glucose (HG) environment is essential. The purpose of this study was to determine whether and how circRNA from human umbilical vein endothelial cell exosomes (HUVEC-Exos) under HG conditions regulates the senescence of vascular smooth muscle cells (VSMCs). Combining circRNA array analysis and bioinformatics, we postulated that the circRNA-0077930-miR-622-Kras CeRNA network plays an important role in inducing senescence in VSMCs. CircRNA-0077930 transmitted by HG-HUVEs-Exos induced senescence of VSMCs by down-regulation of miR-622 expression and up-regulation of Kras, p21, p53 and p16 expression. Moreover, the lactate dehydrogenase (LDH) activity was significantly increased while anti-oxidative stress marker (superoxide dismutase, SOD) activity was reduced in HG-HUVEC-Exos treatment VSMCs. Finally, HG-HUVEC-Exos with depleted-circRNA-0077930 is no longer able to induce cellular senescence in VSMCs. These findings provided a new light on the effective treatment of VSMC senescence. SIGNIFICANCE OF THE STUDY: Previous studies have shown that endothelial cell senescence is closely related to smooth muscle cell aging. Here, for the first time, we proved that the HG-HUVECs derived exosomes induced the VSMCs senescence by circRNA0077930-miR622-Kras CeRNA network. The circRNA-0077930-depleted exosomes would lose the ability to promote cellular senescence of VSMCs.

Cellular Senescence in Arterial Diseases

Cell-proliferation potency is limited, as cells cannot proceed through the cell cycle continually. Instead, they eventually show an irreversible arrest of proliferation, commonly referred to as cellular senescence. Following the initial discovery of this phenomenon by Hayflick et al., studies have indicated that cells are also destined to undergo aging. In addition to the irreversible termination of proliferation, senescent cells are characterized by a flattened and enlarged morphology. Senescent cells become pro-inflammatory and contribute to the initiation and maintenance of sustained chronic sterile inflammation. Aging is associated with the accumulation of senescent cells in the cardiovascular system, and in general these cells are considered to be pathogenic because they mediate vascular remodeling. Recently, genetic and pharmacological approaches have enabled researchers to eliminate senescent cells both in vitro and in vivo. The term “senolysis” is now used to refer to the depletion of senescent cells, and evidence indicates that senolysis contributes to the reversal of age-related pathogenic phenotypes without the risk of tumorigenesis. The concept of senolysis has opened new avenues in research on aging, and senolysis may be a promising therapeutic approach for combating age-related disorders, including arterial diseases.

Expression profiles of circRNAs and the potential diagnostic value of serum circMARK3 in human acute Stanford type A aortic dissection

CircRNAs are involved in a variety of human diseases, however, the expression profiles and the potential diagnostic value of circRNAs in human acute Stanford type A aortic dissection (AAAD) remains largely unknown. In this study, high-throughput RNA sequencing (RNA-Seq) was used to investigate the differentially expressed circRNAs, microRNAs (miRs) and mRNAs in human AAAD tissues (n = 10) compared with normal aortic tissues (n = 10). The results of RNA-Seq revealed that 506 circRNAs were significantly dysregulated (P<0.05, false discovery rate, FDR<0.05, fold change>2). The subsequent weighted gene correlation network analysis and the following co-expression network analysis revealed that tyrosine-protein kinase Fgr might play important roles in the occurrence and development of AAAD. According to the circRNA-miRNA-mRNA network, we found that the upstream regulatory molecule of Fgr is circMARK3. Finally, a receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of the serum circMARK3 as biomarkers for AAAD (cutoff value = 1.497, area under the curve = 0.9344, P < 0.0001, sensitivity = 90.0%, specificity = 86.7%). These results provided a preliminary landscape of circRNAs expression profiles and indicated that circMARK3 was a potential biomarker for AAAD diagnosis.

Interleukin-3 stimulates matrix metalloproteinase 12 production from macrophages promoting thoracic aortic aneurysm/dissection

Thoracic aortic aneurysm and dissection (TAAD) is due to degeneration of the aorta and causes a high mortality rate, while molecular mechanisms for the development of TAAD are still not completely understood. In the present study, 3-aminopropionitrile (BAPN) treatment was used to induce TAAD mouse model. Through transcriptome analysis, we found the expression levels of genes associated with interleukin-3 (IL-3) signaling pathway were up-regulated during TAAD development in mouse, which were validated by real-time PCR. IL-3 positive cells were increased in TAAD mouse aortas, especially for smooth muscle cells (SMCs). IL-3 deficiency reduced BAPN-induced TAAD formation. We then examined the matrix metalloproteinases (MMPs) expression during TAAD formation in both wild-type and IL-3 deficient mice, showing that MMP12 were significantly down-regulated in IL-3 deficient aortas. Mechanistically, we found recombinant IL-3 could increase MMP12 production and activity from macrophages in vitro Silencing of IL-3 receptor β, which was mainly expressed in macrophages but not SMCs, diminished the activation of c-Jun N terminal kinase (JNK)/extracellular-regulated protein kinases 1/2 (ERK1/2)/AP-1 signals, and decreased MMP12 expression in IL-3 stimulated macrophages. Moreover, both circulating and aortic inflammation were decreased in IL-3 deficient aortas. Taken together, our results demonstrated that IL-3 stimulated the production of MMP12 from macrophages by a JNK- and ERK1/2-dependent AP-1 pathway, contributing to TAAD formation. Thus, the IL-3/IL-3Rβ/MMP12 signals activation may be an important pathological mechanism for progression of TAAD.

A reproducible swine model of proximal descending thoracic aortic aneurysm created with intra-adventitial application of elastase

OBJECTIVE

Animal models are required to explore the mechanisms of and therapy for proximal descending thoracic aortic aneurysm (TAA). This study aimed to establish a reproducible swine model of proximal descending TAA that can further explain the occurrence and progression of proximal descending TAA.

METHODS

Eighteen Chinese Wuzhishan miniature pigs (30.32 ± 1.34 kg) were randomized into the elastase group (n = 12) and the control group (n = 6). The elastase group received intra-adventitial injections of elastase (5 mL, 20 mg/mL), and the control group received injections of physiologic saline solution. A 4-cm descending thoracic aortic segment proximal to the left subclavian artery was isolated. The distance between the left subclavian artery and the injection starting point of the descending thoracic aorta was 0.5 cm. Elastic protease was circumferentially injected intra-adventitially into the isolated segment of the aortic wall in the elastase group by a handmade bent syringe. The length of the elastic protease injection was 2 cm. An average of 12 injection points were distributed in this 2-cm aortic segment. Each injection point used about 0.4 mL of elastic protease. The distance between two injection points was about 1.5 cm. All animals underwent digital subtraction angiography preoperatively and 3 weeks after operation. Three weeks after TAA induction, aortas were harvested for biochemical and histologic measurements.

RESULTS

All animals in the elastase group developed TAAs. No aneurysms were observed in the control group. The distance between the left subclavian artery and the TAA was 8.00 ± 4.19 mm. Preoperative and postoperative aortic diameters of the elastase group were 15.42 ± 0.43 mm and 24.53 ± 1.41 mm, respectively (P < .0001). Preoperative and postoperative aortic diameters of the control group were 15.31 ± 0.33 mm and 15.57 ± 0.40 mm, respectively (P = .5211). The changes of aortic structure and composition included reduction of smooth muscle cells and degradation of elastic fibers. Levels of matrix metalloproteinases 2 and 9 were increased in TAA tissue.

CONCLUSIONS

This study established a reproducible large animal model of proximal descending TAA. This model has the same biochemical characteristics as human aneurysms in the aspects of aortic expansion, aortic middle-level degeneration, and changes in the levels of matrix metalloproteinases and provides a platform for further study.

Haplodeficiency of Ataxia Telangiectasia Mutated Accelerates Heart Failure After Myocardial Infarction

Background

Cell senescence is involved in the process of organ damage and repair; however, the underlying molecular mechanism needs to be further explored.

Methods and Results

Senescence‐related genes (ie, p21, p53, and ataxia telangiectasia mutated [ATM]) were shown to be elevated after myocardial infarction (MI) in both mouse and human hearts. Ten‐ to 12‐week‐old male wild‐type littermates (ATM^+/+) and ATM heterozygous mice (ATM^+/−) were subjected to MI. Cardiac echography showed that ATM haplodeficiency did not affect the survival rate but aggravated heart failure at day 28 post MI. Histologic analysis showed increased fibrosis in the noninfarct area of ATM^+/− mice compared with that in ATM^+/+ mice. Senescence‐associated β‐galactosidase staining showed that the number of senescent fibroblasts was decreased when ATM was haplodeficient both in vivo and in vitro. Costaining of α‐smooth muscle actin with p53 or p19 showed fewer senescent myofibroblasts in ATM^+/− mouse hearts. Moreover, angiogenesis was also examined using the endothelial markers CD31 both at early (day 7) and late stages (day 28) after MI, and ATM haplodeficiency reduced angiogenesis after MI. Finally, cardiac fibroblasts were isolated from infarcted mouse heart and the medium were tested for its capacity of endothelial tubing formation, revealing that ATM haplodeficiency led to lower vascular endothelial growth factor production from cardiac fibroblast and reduced capacity of endothelial tube formation in vitro.

Conclusions

The present study shows that ATM haplodeficiency decreases fibroblast senescence and vascular endothelial growth factor production and impaired angiogenesis in response to MI, leading to accelerated heart failure.

Toll-like receptor-4 signaling pathway in aorta aging and diseases: "its double nature"

Recent advances in the field of innate immunity have revealed a complex role of innate immune signaling pathways in both tissue homeostasis and disease. Among them, the Toll-like receptor 4 (TLR-4) pathways has been linked to various pathophysiological conditions, such as cardiovascular diseases (CVDs). This has been interrogated by developing multiple laboratory tools that have shown in animal models and clinical conditions, the involvement of the TLR-4 signaling pathway in the pathophysiology of different CVDs, such as atherosclerosis, ischemic heart disease, heart failure, ischemia-reperfusion injury and aorta aneurysm. Among these, aorta aneurysm, a very complex pathological condition with uncertain etiology and fatal complications (i.e. dissection and rupture), has been associated with the occurrence of high risk cardiovascular conditions, including thrombosis and embolism. In this review, we discuss the possible role of TLR-4 signaling pathway in the development of aorta aneurysm, considering the emerging evidence from ongoing investigations. Our message is that emphasizing the role of TLR-4 signaling pathway in aorta aneurysm may serve as a starting point for future studies, leading to a better understanding of the pathophysiological basis and perhaps the effective treatment of this difficult human disease.

ER stress dependent microparticles derived from smooth muscle cells promote endothelial dysfunction during thoracic aortic aneurysm and dissection

The degeneration of vascular smooth muscle cell(s) (SMC) is one of the key features of thoracic aortic aneurysm and dissection (TAAD). We and others have shown that elevated endoplasmic reticulum (ER) stress causes SMC loss and TAAD formation, however, the mechanism of how SMC dysfunction contributes to intimal damage, leading to TAAD, remains to be explored. In the present study, in vitro assay demonstrated that elevated mechanical stretch (18% elongation, 3600 cycles/h) stimulated the ER stress response and microparticle(s) (MP) production from both SMC and endothelial cell(s) (EC) in a time-dependent manner. Treatment of EC with isolated MP led to anoikis, which was determined by measuring the fluorescence of the ethidium homodimer (EthD-1) and Calcein AM cultured in hydrogel-coated plates and control plates. MP stimulation of EC also up-regulated the mRNA levels of inflammatory molecules (i.e. Vascular cellular adhesion molecular-1 (VCAM-1)), intercellular adhesion molecular-1 (ICAM-1), interleukin-1β (IL-1β), and interleukin-6 (IL-6)). Use of an ER stress inhibitor or knockout of CHOP decreased mechanical stretch-induced MP production in SMC. In vivo, administration of an ER stress inhibitor or knockout of CHOP suppressed both apoptosis of EC and the infiltration of inflammatory cells. Moreover, TAAD formation was also suppressed by the administration of an ER stress inhibitor. In conclusion, our study demonstrates that elevated mechanical stretch induces MP formation in SMC leading to endothelial dysfunction, which is ER stress dependent. The inhibition of ER stress suppressed EC apoptosis, inflammation in the aorta, and TAAD development.