Pathogenesis Of Thoracic Aortic Dissection Research Articles

Enhanced expression of miR-20a driven by nanog exacerbated the degradation of extracellular matrix in thoracic aortic dissection

Thoracic aortic dissection (TAD) is a life-threatening vascular disease manifested as intramural bleeding in the medial layers of the thoracic aorta. The key histopathologic feature of TAD is medial degeneration, characterized by depletion of vascular smooth muscle cells (VSMCs) and degradation of extracellular matrix (ECM). MicroRNA, as essential epigenetic regulators, can inhibit the protein expression of target genes without modifying the sequences. This study aimed to elucidate the role and underlying mechanism of miR-20a, a member of the miR-17-92 cluster, in regulating ECM degradation during the pathogenesis of TAD. The expression of the miR-17-92 cluster was significantly increased in synthetic VSMCs derived from TAD lesions compared to contractile VSMCs isolated from normal thoracic aortas. Notably, the expression of miR-20a was increased in VSMCs in response to serum exposure and various stimuli. In TAD lesions, the expression of miR-20a was significantly negatively correlated with that of elastin. Elevated expression of miR-20a was also observed in thoracic aortas of TAD mice induced by β-aminopropionitrile fumarate and angiotensin II. Overexpression of miR-20a via mimic transfection enhanced the growth and invasive capabilities of VSMCs, with no significant impact on their migratory activity or the expression of phenotypic markers (α-SMA, SM22, and OPN). Silencing of miR-20a with inhibitor transfection mitigated the hyperactivation of MMP2 in VSMCs stimulated by PDGF-bb, as evidenced by reduced levels of active-MMP2 and increased levels of pro-MMP2. Subsequently, TIMP2 was identified as a novel target gene of miR-20a. The role of miR-20a in promoting the activation of MMP2 was mediated by the suppression of TIMP2 expression in VSMCs. In addition, the elevated expression of miR-20a was found to be directly driven by Nanog in VSMCs. Collectively, these findings indicate that miR-20a plays a crucial role in maintaining the homeostasis of the thoracic aortic wall during TAD pathogenesis and may represent a potential therapeutic target for TAD.

Branched-chain amino acid catabolic defect in vascular smooth muscle cells drives thoracic aortic dissection via mTOR hyperactivation

Metabolic reprogramming of vascular smooth muscle cell (VSMC) plays a critical role in the pathogenesis of thoracic aortic dissection (TAD). Previous researches have mainly focused on dysregulation of fatty acid or glucose metabolism, while the impact of amino acids catabolic disorder in VSMCs during the development of TAD remains elusive. Here, we identified branched-chain amino acid (BCAA) catabolic defect as a metabolic hallmark of TAD. The bioinformatics analysis and data from human aorta revealed impaired BCAA catabolism in TAD individuals. This was accompanied by upregulated branched-chain α-ketoacid dehydrogenase kinase (BCKDK) expression and BCKD E1 subunit alpha (BCKDHA) phosphorylation, enhanced vascular inflammation, and hyperactivation of mTOR signaling. Further in vivo experiments demonstrated that inhibition of BCKDK with BT2 (a BCKDK allosteric inhibitor) treatment dephosphorylated BCKDHA and re-activated BCAA catabolism, attenuated VSMCs phenotypic switching, alleviated aortic remodeling, mitochondrial reactive oxygen species (ROS) damage and vascular inflammation. Additionally, the beneficial actions of BT2 were validated in a TNF-α challenged murine VSMC cell line. Meanwhile, rapamycin conferred similar beneficial effects against VSMC phenotypic switching, cellular ROS damage as well as inflammatory response. However, co-treatment with MHY1485 (a classic mTOR activator) reversed the beneficial effects of BT2 by reactivating mTOR signaling. Taken together, the in vivo and in vitro evidence showed that impairment of BCAA catabolism resulted in aortic accumulation of BCAA and further caused VSMC phenotypic switching, mitochondrial ROS damage and inflammatory response via mTOR hyperactivation. BCKDK and mTOR signaling may serve as the potential drug targets for the prevention and treatment of TAD.

SPINT2 is involved in the proliferation, migration and phenotypic switching of aortic smooth muscle cells: Implications for the pathogenesis of thoracic aortic dissection.

Thoracic aortic dissection (TAD) is a severe and extremely dangerous cardiovascular disease. Proliferation, migration and phenotypic switching of vascular smooth muscle cells (SMCs) are major pathogenetic mechanisms involved in the development of TAD. The present study was designed to investigate the expression and potential function of serine peptidase inhibitor Kunitz type 2 (SPINT2) in TAD. The gene expression profile data for ascending aorta from patients with TAD were downloaded from the GEO database with the accession number GSE52093. Bioinformatics analysis using GEO2R indicated that the differentially expressed SPINT2 was prominently decreased in TAD. The expression levels of SPINT2 mRNA and protein in aortic dissection specimens and normal aorta tissues were measured using reverse transcription-quantitative PCR and western blotting. SPINT2 expression was downregulated in clinical samples from aortic dissection specimens of patients with TAD compared with the corresponding expression noted in tissues derived from patients without TAD. In vitro, platelet-derived growth factor BB (PDGF-BB) was applied to induce the isolated primary mouse aortic SMC phenotypic modulation (a significant upregulation in the expression levels of synthetic markers), and the SMCs were infected with the adenoviral vector, Ad-SPINT2, to construct SPINT2-overexpressed cell lines. SMC viability was detected by an MTT assay and SMC proliferation was detected via the presence of Ki-67-positive cells (immunofluorescence staining). To explore the effects of SPINT2 on SMC migration, a wound healing assay was conducted. ELISA and western blotting assays were used to measure the content and expression levels of MMP-2 and MMP-9. The expression levels of vimentin, collagen I, α-SMA and SM22α were measured using western blotting. The PDGF-BB-induced proliferation and migration of SMCs were recovered by SPINT2 overexpression. The increase in the expression levels of SPINT2 reduced the expression levels of active matrix metalloproteinases (MMPs), MMP-2 and MMP-9. Overexpression of SPINT2 suppressed SMC switching from a contractile to a synthetic type, as evidenced by decreased vimentin and collagen I expression levels along with increased α-smooth muscle actin and smooth muscle protein 22-α expression levels. Furthermore, activation of ERK was inhibited in SPINT2-overexpressing SMCs. A specific ERK agonist, 12-O-tetradecanoylphorbol-13-acetate, reversed the SPINT2-mediated inhibition of SMC migration and the phenotypic switching. Collectively, the data indicated that SPINT2 was implicated in the proliferation, migration and phenotypic switching of aortic SMCs, suggesting that it may be involved in TAD progression.

Progression of Thoracic Aortic Dissection Is Aggravated by the hsa_circ_0007386/miR-1271-5P/IGF1R/AKT Axis via Induction of Arterial Smooth Muscle Cell Apoptosis

The molecular mechanisms associated with thoracic aortic dissection (TAD) remain poorly understood. A comprehensive high-throughput sequencing-based analysis of the circRNA-miRNA-mRNA competitive endogenous RNA (ceRNA) regulatory network in TAD has not been conducted. The purpose of this study is to identify and verify the key ceRNA networks which may have crucial biological functions in the pathogenesis of TAD. Gene expression profiles of the GSE97745, GSE98770, and GSE52093 datasets were acquired from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified using the GEO2R tools. Protein-protein interaction (PPI) networks of the hub genes were constructed using STRING; the hub genes and modules were identified by MCODE and CytoHubba plugins of the Cytoscape. We analyzed the hub genes using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The functions of these hub genes were assessed using Cytoscape software. Our data-along with data from GSE97745, GSE98770, and GSE52093-were used to verify the findings. Upon combined biological prediction, a total of 11 ce-circRNAs, 11 ce-miRNAs, and 26 ce-mRNAs were screened to construct a circRNA-miRNA-mRNA ceRNA network. PPI network and module analysis identified four hub nodes, including IGF1R, JAK2, CSF1, and GAB1. Genes associated with the Ras and PI3K-Akt signaling pathways were clustered in the four hub node modules in TAD. The node degrees were most significant for IGF1R, which were also the most significant in the two modules (up module and hub module). IGF1R was selected as a key gene, and the hsa_circ_0007386/miR-1271-5P/IGF1R/AKT regulatory axis was established. The relative expression levels of the regulatory axis members were confirmed by RT-PCR in 12 samples, including TAD tissues and normal tissues. Downregulation of IGF1R expression in smooth muscle cells (SMCs) was found to induce apoptosis by regulating the AKT levels. In addition, IGF1R showed high diagnostic efficacy in both AD tissue and blood samples. The hsa_circ_0007386/miR-1271-5P/IGF1R/AKT axis may aggravate the progression of TAD by inducing VSMCs apoptosis. CeRNA networks could provide new insights into the underlying molecular mechanisms of TAD. In addition, IGF1R showed high diagnostic efficacy in both tissue and plasma samples in TAD, which can be considered as a diagnostic marker for TAD.

Generation of a Human iPSC (ICSSUi002-A) with MTHFR SNP (rs1801133, TT) from Thoracic Aortic Dissection Patient

Thoracic aortic dissection is a devastating cardiovascular disease with an increasing annual incidence. The homozygous mutation in rs1801133 site has been accepted for decreased enzyme activity of mutant MTHFR protein, contributing to an accumulated homocysteine in blood. Recently, elevated homocysteine level is causally associated with an increased risk of cardiovascular disease. Conversely, the relationship between rs1801133 and thoracic aortic dissection is poorly understood. Here, the generated human induced pluripotent stem cell (iPSC) line provided a novel strategy for investigating the underlying mechanism of MTHFR mutation (rs1801133, TT) and its implication in the pathogenesis of thoracic aortic dissection.

Induction of thoracic aortic dissection: a mini-review of β-aminopropionitrile-related mouse models.

Thoracic aortic dissection (TAD) is one of the most lethal aortic diseases due to its acute onset, rapid progress, and high rate of aortic rupture. The pathogenesis of TAD is not completely understood. In this mini-review, we introduce three emerging experimental mouse TAD models using β-aminopropionitrile (BAPN) alone, BAPN for a prolonged duration (four weeks) and then with added infusion of angiotensin II (AngII), or co-administration of BAPN and AngII chronically. We aim to provide insights into appropriate application of these three mouse models, thereby enhancing the understanding of the molecular mechanisms of TAD.

Dysregulated long non-coding RNAs involved in regulation of matrix degradation during type-B aortic dissection pathogenesis.

Thoracic aortic dissection (TAD) is a catastrophic disease with the rupture of aortic media resulted mainly from the degradation of extracellular matrix. With the deep study of long non-coding RNAs (lncRNAs) in cardiovascular diseases, the correlation between lncRNAs and the TAD pathogenesis is under revealed. In this study, we aimed to screen the differentially expressed lncRNAs involved in the regulation of matrix degradation during type-B aortic dissection (TBAD), whose pathogenesis is more similar to atherosclerosis. A total of 393 aberrantly expressed lncRNAs and 432 aberrantly expressed mRNAs were identified in the descending aortic samples from TBAD patients. Then, co-expression analysis was applied to analyze the correlation between the top five differentially expressed lncRNAs and aberrantly expressed mRNAs, so as to screen the lncRNAs involved in the regulation of matrix degradation. The results showed that two transcripts from lnc-TNFSF14 (lnc-TNFSF14-2, and lnc-TNFSF14-3) were negatively interacted with MMP14 and MMP19. Subsequently, quantitative real-time PCR assay confirmed that lnc-TNFSF14-2 were negatively correlated with MMP14 (rs = - 0.8180) and MMP19 (rs = - 0.8449), and lnc-TNFSF14-3 was also negatively correlated with MMP14 (rs = - 0.7098) and MMP19 (rs = - 0.7728) in descending aorta from TBAD patients (n = 20). Overall, our study found the aberrant lncRNAs expression profiles in TBAD, and identified lnc-TNFSF14 as a potential target regulating matrix degradation. The results also provided crucial clues for lncRNAs function research on TBAD development.

Efficient detection of differentially methylated regions in the genome of patients with thoracic aortic dissection and association with MMP2 hypermethylation.

DNA methylation is known to regulate the expression of numerous genes but its role in the pathogenesis of thoracic aortic dissection (TAD) has remained largely elusive. In the present study, the DNA methylome of patients with TAD was analyzed using a methylation microarray and bisulfite pyrosequencing was used to determine whether the hypermethylation of matrix metalloproteinase 2 (MMP2) specifically is associated with TAD. Chip-based whole-DNA methylome analysis was performed on 4 male patients with TAD and 4 male healthy controls using an Illumina HumanMethylation EPIC 850K BeadChip. The resulting data were analyzed by clustering and principal component analysis, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed on the differentially methylated genes to interrogate their biological functions. Compared to the healthy controls, 3,362 loci were differentially methylated in the patients with TAD with a statistical significance of P<0.05, while 1,223 loci had a significance of P<0.01. Among these loci, 2,019 were hypermethylated and 1,343 were hypomethylated. From GO analysis within the biological process category, the MMP2, MMP14 and WNT2B genes were identified. enrichment was observed for loci involved in cellular component organization, enzyme-linked receptor protein signaling pathways (potentially having a key role in the development of cardiopulmonary function disorders) and vascular reconstruction. Bisulfite pyrosequencing of plasma samples indicated significantly increased methylation (P<0.01) of the CpG site at position 2 in the promoter of MMP2 in the TAD group relative to the healthy controls, and the mean methylation level of four CpG sites on the MMP2 gene in the TAD group was slightly higher than that in the control group, but not significantly. Hypermethylation of the MMP2 promoter may be a promising novel diagnostic and prognostic biomarker for TAD. Future studies on the epigenetics of biomarkers linked to vascular reconstruction and immune function may provide further insight into the pathogenesis and progression of TAD.

Potential function of microRNAs in thoracic aortic aneurysm and thoracic aortic dissection pathogenesis.

Thoracic aortic aneurysm (TAA) and thoracic aortic dissection (TAD) are aortic diseases known as 'silent killers'. While TAA is characterized by an enlargement of at least half of the normal aortic diameter, TAD is characterized by progressive pseudo‑lumen formation, which results in the gradual separation of the aortic wall layers. In the present study, a total of 28 serum samples from nine patients with TAA, nine patients with TAD and ten healthy individuals were studied. The aim of the present study was to investigate the expression profiles of hsa‑microRNA(miR)‑143‑3p and hsa‑miR‑22‑3p in TAA and TAD in order to identify candidate miRNAs that are responsible for the pathogenesis of the diseases. Following the detection of target mRNAs from candidate miRNAs by bioinformatic tools, the expression profiles of target mRNAs were analyzed. A quantitative polymerase chain reaction was performed to detect Kirsten rat sarcoma viral oncogene homolog (KRAS), mitogen‑activated protein kinase (MAPK) 7, MAPK14 and transgelin (TAGLN) mRNA expression profiles. The results of the comparison with control group demonstrated that the increase in the expression levels of hsa‑miR‑143‑3p (P=0.017) and hsa‑miR‑22 (P=0.03) candidate miRNAs were statistically significant in the TAA group, but not in the TAD group. The expression of KRAS and MAPK7 mRNAs decreased in the two groups compared with the control group. The level of expression of MAPK14 decreased in the TAD group, but increased in the TAA group compared with the control group. TAGLN mRNA expression level increased in the two groups. The statistically significant difference in the expression of hsa‑miR‑143‑3p suggests that hsa‑miR‑143‑3p may be a potential biomarker for TAA, as the expression of the target mRNAs KRAS and MAPK7 decreased and the miRNA‑mRNA association was negatively correlated. These miRNAs and their associated genes may serve important functions in TAA formation, the altered expression of which may be important in the pathogenesis of TAA.

MicroRNA-134-5p Regulates Media Degeneration through Inhibiting VSMC Phenotypic Switch and Migration in Thoracic Aortic Dissection

Abnormal phenotypic switch, migration, and proliferation of vascular smooth muscle cells (VSMCs) are hallmarks for pathogenesis of thoracic aortic dissection (TAD). In the current study, we identified miR-134-5p as a critical regulator controlling human VSMC phenotypic switch and migration to investigate whether miR-134-5p affects human VSMC functions and development of TAD. Using miRNA microarray of aorta specimens from 12 TAD and 12 controls, we identified miR-134-5p, which was significantly downregulated in TAD tissues. With qPCR detection, we found that miR-134-5p was also evidently decreased in human AoSMCs. Ectopic expression of miR-134-5p obviously promoted VSMC differentiation and expression of contractile markers, such as α-SMA, SM22α, and MYH11. miR-134-5p potently inhibited PDGF-BB-induced VSMC phenotypic switch and migration. We further identified STAT5B and ITGB1 as downstream targets of miR-134-5p in human VSMCs and proved them to be mediators in VSMC phenotypic switch and progression of TAD. Finally, Ad-miR-134-5p obviously suppressed the aorta dilatation and vascular media degeneration by 39% in TAD mice after vascular injury induced by Ang II. Our findings revealed that miR-134-5p was a novel regulator in vascular remodeling and pathological progress of TAD via targeting STAT5B/ITGB1 expression. Targeting miR-134-5p or its downstream molecules in VSMCs might develop new avenues in clinical treatment of TAD.

Upregulation of miR-146a-5p is associated with increased proliferation and migration of vascular smooth muscle cells in aortic dissection.

BackgroundThis study aimed to investigate whether miR‐146a‐5p was involved in the pathogenesis of thoracic aortic dissection (AD) via regulating the biological function of vascular smooth muscle cells (VSMCs).MethodsCirculating miR‐146a‐5p level was measured by quantitative polymerase chain reaction (qPCR) in AD patients and healthy controls. Human dissected aortic samples were obtained from patients with thoracic AD Stanford type A undergoing surgical repair, and normal control samples were from organ donors who died from nonvascular diseases. The expression level of miR‐146a‐5p was detected using qPCR in each sample. The expression of SMAD4, which is involved in the TGF‐β pathway and indicated as the target gene of miR‐146a‐5p, was measured by qPCR and Western blot analysis at the mRNA level and protein level, respectively. Subsequently, VSMCs were transfected with miR‐146a‐5p mimics or inhibitors in vitro. VSMC proliferation and migration were detected using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide and Transwell assay, respectively. Flow cytometry was used to identify apoptosis. The expression of SMAD4 in VSMCs was determined using qPCR and Western blot analysis.ResultsPlasma level of miR‐146a‐5p is significantly higher in the AD group as compared with the control group. The expression of miR‐146a‐5p was significantly upregulated in dissected aorta compared with controls (P < 0.05). The overexpression of miR‐146a‐5p significantly induced VSMC proliferation and migration in vitro.ConclusionsThe expression of SMAD4 was modulated by miR‐146a‐5p. miR‐146a‐5p induced VSMC proliferation and migration through targeting SMAD4 and hence might be potentially involved in the development of AD.

Involvement of B cells in the pathophysiology of β-aminopropionitrile-induced thoracic aortic dissection in mice

Thoracic aortic dissection (TAD) is a life-threatening disease that is characterized by an inflammatory response. Innate and cellular immunity has long been known to be involved in TAD, but the role of humoral immunity in the pathophysiology of TAD remains unknown. We administered the lysyl oxidase inhibitor β-aminopropionitrile (BAPN; 1 g/kg/day) in 3-week-old male C57BL/6J mice for 4 weeks to establish an animal model of TAD. Animals that died were immediately dissected. Animals that survived were sacrificed on days 7, 14, and 28 after BAPN challenge. The incidence and rupture rates of BAPN-induced TAD were 90% (9/10) and 70% (7/10), respectively, at 28 days. Victoria blue-nuclear fast red staining of aortic tissue revealed elastic lamellae destruction and the formation of a false lumen in the BAPN group. Hematoxylin-eosin staining revealed the infiltration of both plasmacytoid mononuclear cells and polymorphonuclear inflammatory cells in TAD tissues. Enzyme-linked immunosorbent assay and immunohistochemistry indicated that plasma immunoglobin M (IgM) and IgG were elevated at 7, 14, and 28 days, and CD19-positive B cells infiltrated into the adventitia of aortic tissue in BAPN-treated mice. The transcriptional analysis showed an increase in the expression of B cell receptor signaling-associated genes. These results indicate that B cells and immunoglobulins might participate in the pathogenesis of TAD, suggesting that humoral immunity may be a possible therapeutic target for TAD.

Interleukin-6 downregulated vascular smooth muscle cell contractile proteins via ATG4B-mediated autophagy in thoracic aortic dissection.

Interleukin-6 (IL-6) overexpression played an important role in the pathogenesis of thoracic aortic dissection (TAD). Our previous study found enhanced autophagy accompanying with contractile proteins α smooth muscle actin (α-SMA) and smooth muscle 22α (SM22α) degradation in TAD aortic vascular smooth muscle cells (VSMCs). Autophagy is an important way for intracellular proteins degradation, while IL-6 has been found as a contributing factor of autophagy in some cancers. These indicated IL-6 might contribute to the occurrence of TAD by promoting autophagy-induced contractile proteins degradation, which has not been investigated. The aim of the present study is to verify this hypothesis and investigate the mechanism of it. We collected 10 TAD and 10 control aortic specimens from patients underwent TAD surgical repair and coronary artery bypass grafting, respectively. Quantitative real-time polymerase chain reaction was used to detect mRNA expression. Protein expression level was assessed by enzyme-linked immunosorbent assay, western blot, and immunohistochemistry. Microtubule-associated protein 1 light chain 3 beta overexpression adenovirus with green and red fluorescent protein tags and transmission electron microscopy were used to detect autophagy level in VSMCs. 3-Methyladenine (3-MA) and chloroquine were used to block autophagy in human VSMCs. Experiment results showed that the expression of IL-6 was significantly increased accompanying with up-regulated autophagy in TAD aortic wall compared with controls. In vitro results showed that IL-6 stimulation decreased the expression of VSMCs contractile proteins α-SMA and SM22α accompanying with up-regulated autophagy. Blocking autophagy with 3-MA or chloroquine inhibited IL-6 induced α-SMA and SM22α degradation. Further investigation showed that autophagy-related 4B cysteine peptidase (ATG4B) was significantly overexpressed in TAD aortic wall and played important role in IL-6 induced autophagy up-regulation. ATG4B knockdown blocked IL-6-induced autophagy and α-SMA and SM22α degradation, while ATG4B overexpression partly replaced the function of IL-6 in human VSMCs. In conclusion, our study demonstrated that IL-6 downregulated expression of VSMCs contractile proteins α-SMA and SM22α via enhancing ATG4B-mediated autophagy in TAD.

Disturbed P53-MDM2 Feedback Loop Contributes to Thoracic Aortic Dissection Formation and May be a Result of TRIM25 Overexpression

The development of thoracic aortic dissection (TAD) is attributed to a broad range of degenerative, genetic, structural, oxidative, apoptotic, and acquired disease states. In this study, we examined the role of the disturbed p53-MDM2 (murine double minute 2) feedback loop in the formation of TAD, and one of a potential feedback loop regulator, TRIM25 (tripartite motif protein-25). Surgical specimens of the aorta from TAD patients (n=10) and controls (n=10) were tested for α-smooth muscle actin (α-SMA), p53, MDM2, and TRIM25 by western blot, immunohistochemical staining, and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), respectively. When compared with controls, western blot shows that the protein levels of p53, MDM2, and TRIM25 were increased significantly in the aortic media of TAD patients. qRT-PCR further verified that the mRNA expression of MDM2 and TRIM25 was also increased 6- and 4-folds, respectively, in the TAD media of the aortic wall. Immunohistochemistry results showed significantly decreased staining of α-SMA, smooth muscle cells, and more collagen deposition in the media of the aortic wall from patients with TAD. This study provided a new insight into the disturbed p53-MDM2 feedback loop in the pathogenesis of TAD, and this may be because of the TRIM25 overexpression.

Role of regional aortic wall properties in the pathogenesis of thoracic aortic dissection

Objectives. The mechanisms of the location and extension of acute aortic dissection (AD) are only poorly understood. The aim of this study was to compare the cohesion of the non-coronary aortic sinus (NAS) and the ascending aortic wall (AA) using the Dissectometer – a new device for analyses of the mechanical properties of the aorta. Design. The properties of the aortic wall were analyzed with the “Dissectometer” (parameters P7, P8 and P9) in adult patients undergoing aortic root (AR) replacement in two different segments: NAS and AA. The aortic wall thickness (AWT) was measured with a micrometer. Results. Thirty-three adult patients (mean age 65 ± 14 years, 80% male) were included in this study. The aortic wall of the NAS was significantly thinner than that of the AA (1.9 ± 0.4 vs. 2.3 ± 0.4, p < 0.01). In contrast, mechanical stability assessed by cohesion testing was diminished in AA samples compared to NAS samples (P7: 86.0 ± 55.0 vs. 152.3 ± 89.2, p < 0.01; P8: 2.5 ± 1.3 vs. 6.0 ± 3.1, p < 0.01; P9: 3.6 ± 1.4 vs. 7.8 ± 3.2, p < 0.01). Conclusions. This study shows that the wall of the AR is characterized by a thin but stable wall, whereas AA was found to be weaker despite its greater thickness. This difference might be involved in the development and spreading of aortic dissections.

Involvement of Oct4 in the pathogenesis of thoracic aortic dissection via inducing the dedifferentiated phenotype of human aortic smooth muscle cells by directly upregulating KLF5

ObjectiveTo investigate the expression of Oct4 in human thoracic aortic dissection (TAD) and the regulation mechanisms of Oct4 on phenotype transition of human aortic smooth muscle cells (HASMCs). MethodsAortic samples from TAD patients (n = 12) and organ donors (n = 6) were collected. qRT-PCR, western blot, and immunohistochemistry were performed to identify Oct4 expression in aortic media. Immunofluorescence was performed to analyze Oct4 expression in primary HASMCs. Oct4A and Oct4B isoforms were detected. Gain-of-function experiments were performed to determine the effects of Oct4 on HASMC phenotype transition. Chromatin immunoprecipitation, luciferase assay, and rescue experiments were performed to analyze mechanisms of Oct4 on HASMC phenotype transition. ResultsOct4 expression levels, especially the Oct4A isoform, were significantly higher in TAD patients compared with normal controls. Notably, Oct4 presented a strong and strict nuclear localization in primary HASMCs of TAD patients but a mild and diffuse distribution in both cytoplasm and nucleus in the control group. Overexpression of Oct4 induced dedifferentiation of HASMCs characterized by decreased contractile proteins and elevated migration capability. Krüppel-like factor 5 (KLF5) was found to be a directly regulated target gene of Oct4 in HASMCs. Furthermore, downregulation of KLF5 significantly alleviated the effects of Oct4 on phenotype transition of HASMCs. ConclusionsOct4 expression was significantly upregulated in aortic tissues and primary HASMCs of TAD patients. The increased Oct4 induced phenotype transition of HASMCs from the contractile type to the synthetic type by directly upregulating KLF5.

Association of MMP-2 gene haplotypes with thoracic aortic dissection in chinese han population.

BackgroundThoracic aortic dissection (TAD) is the most common life-threatening disorder, and MMP-2 is involved in TAD pathogenesis. Our purpose is to systematically evaluate the association of the MMP-2 gene with TAD risk in Chinese Han population.MethodsIn our case–control study, we recruited 755 unrelated participants: 315 case participants with TAD and 440 controls. Twenty-two tag SNPs were selected from MMP-2 gene and were genotyped. Genotype data were analyzed by logistic regression.ResultsAlthough we did not find any significant association for MMP-2 SNPs using single-marker analysis, we identified many windows with haplotype frequencies significantly different between case participants and control participants using a variable-sized sliding-window strategy. In particular, the most significant association was shown by a 2-SNP window consisting of rs2241145 and rs9928731 (omnibus test: asymptotic Pasym = 7.48 × 10 −5 and empirical Pemp = 0.001867). There were two protective haplotypes: CT (Pasym = 0.00303; odds ratio [OR], 0.403) and GC (Pasym = 0.000976; OR, 0.448).ConclusionsMMP-2 haplotypes are associated with genetic susceptibility to thoracic aortic dissection in Chinese Han population.Electronic supplementary materialThe online version of this article (doi:10.1186/s12872-016-0188-4) contains supplementary material, which is available to authorized users.

Trace Element Changes in Thoracic Aortic Dissection.

Thoracic aortic dissection is a life-threatening condition with an incompletely understood pathogenesis. Trace elements are essential for the functioning of different processes in the body, including the immune system and associated responses to infection/inflammation. Because inflammation may be part of the pathogenesis of thoracic aortic dissection, we investigated whether trace element changes associated with inflammation occur in serum and tissue samples during the disease. The study included 21 patients undergoing surgery for thoracic aortic dissection, 10 forensic autopsy specimens for tissue controls and 23 healthy blood donors for serum controls. Levels of magnesium (Mg), calcium (Ca), vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd) and mercury (Hg) were measured in the aortic tissue and serum by inductively coupled plasma-mass spectrometry (ICP-MS). In the serum, Ca, V, Cu and Zn decreased, whereas Fe increased. In the tissue, Cu and Zn decreased and Fe tended to increase. The Cu/Zn ratio in the serum, a marker of infection/inflammation, did not change in the patients. Concerning trace element changes in the serum and tissue, our data do not support the hypothesis that inflammation is involved in the pathogenesis of thoracic aortic dissection.

Comparative tissue proteomics analysis of thoracic aortic dissection with hypertension using the iTRAQ technique.

To identify differentially expressed proteins from the aortic tissue of thoracic aortic dissection (TAD) with hypertension and normal aorta and to explore the potential molecular pathogenesis of TAD. Aortic tissue samples were collected from two groups of age- and gender-matched patients with TAD and normal aorta. These samples were subjected to isobaric tags for relative and absolute quantitation analysis to identify the proteins involved in TAD. Signalling pathways were analysed using the Metacore software, and the identified proteins were validated by western blotting. A total of 36 proteins were identified between two groups, with 19 of them being significantly down-regulated and 17 up-regulated in patients with TAD. Proteins including fibrillin-1, emilin-1, decorin, protein DJ-1 and histone H4 were validated by western blotting. The enrichment analysis performed using the Metacore process networks data showed that cell adhesion_cell-matrix interactions, proteolysis_extracellular matrix (ECM) remodelling and inflammation_interleukin 6 (IL-6) signalling were the main protein interaction networks involved in TAD. We further observed indications of increased transforming growth factor-β (TGF-β) signalling and impaired aortic wall remodelling, both of which may be molecular mechanisms for the pathogenesis of TAD. The differentially expressed proteins identified in our study are mainly involved in cell-matrix interaction, ECM remodelling and inflammation. These mechanisms, combined with the TGF-β signalling pathway, may play an important role in the pathogenesis of TAD.

Association of the polymorphisms of MMP-9 and TIMP-3 genes with thoracic aortic dissection in Chinese Han population

Thoracic aortic dissection (TAD) is the most common life-threatening disorder, and a shifted balance of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) is involved in TAD pathogenesis. The aim of this study was to evaluate the association of 4 single-nucleotide polymorphisms (SNPs) in MMP-9 and TIMP-3 genes with TAD risk in Chinese Han population. A total of 206 Chinese patients with TAD and 180 controls were included in this study. Four SNPs (rs3918249, rs2274756, rs9609643 and rs8136803) were genotyped using high-throughput MALDI-TOF mass spectrometry. Allele and genotype association analyses were conducted using PLINK. All the 4 SNPs resulted in Hardy-Weinberg equilibrium in patients and controls. The G allele frequency for the MMP-9 SNP rs2274756 was significantly higher in female TAD patients than in female controls (P=0.0099). Moreover, after adjusting for traditional cardiovascular risk factors (sex, age, hypertension, dyslipidemia, diabetes and smoking habit), the rs2274756 polymorphism (odds ratio: 0.30; 95% confidence interval: 0.11 to 0.79, P=0.015) resulted in an independent susceptibility factor for TAD in females. No associations were found between the other SNPs and TAD. The results provide strong evidence for an association between MMP-9 SNP rs2274756 and female TAD risk in Chinese Han population.