Pathogenesis Of Acute Aortic Dissection Research Articles

MiR-590-3p Promotes the Phenotypic Switching of Vascular Smooth Muscle Cells by Targeting Lysyl Oxidase.

We investigated the clinical characteristics of patients with acute aortic dissection (AAD) and miR-590-3p levels in serum, tissue, and vascular smooth muscle cells. The effect of miR-590-3p on the vascular smooth muscle cell phenotype was assessed, and the regulation of lysyl oxidase by miR-5903p was determined. C57BL/6 mice were used to investigate the incidence of AAD and effects of miR-5903p on AAD. The miR-590-3p levels were measured in the aortae of mice, and hematoxylin and eosin staining and Masson staining were performed to identify the morphological features of the aorta. Comparative analysis revealed significant differences in clinical characteristics between patients with AAD and healthy control subjects, with most patients with AAD exhibiting concomitant hypertension and nearly 50% having atherosclerosis. Lysyl oxidase was a direct target of miR-590-3p. Lysyl oxidase overexpression inhibited switching of the vascular smooth muscle cell phenotype from contractile to synthetic, but miR-590-3p overexpression significantly reversed this change. In the mouse model, miR-590-3p upregulation increased the incidence of AAD to 93.3%, and its incidence decreased to 13.3% after miR-590-3p inhibition. Hematoxylin and eosin and Masson staining revealed that the miR-590-3p agomiR group had a greater loss of the contractile phenotype in the dissected aortic wall and an increased number of muscle fibers in the aortic wall, which contributed to thickening of the aortic wall and the formation of a false lumen in aortic dissection. miR-590-3p might be pivotal in the pathogenesis of AAD. Thus, targeting miR-590-3p or its downstream pathways could represent a therapeutic approach for AAD.

Study on Proteomics-Based Aortic Dissection Molecular Markers Using iTRAQ Combined With Label Free Techniques.

Background: Aortic dissection refers to the separation of aortic media and extension along the long axis to form the true and false chambers of the aortic wall. 65–70% of the patients died of cardiac tamponade, arrhythmia, dissection rupture, etc. At present, echocardiography, computed tomography angiography (CTA), etc. are the main diagnosis tools for aortic dissection. To date, there is no rapid serum molecular marker that can be used for differential diagnosis and risk assessment. Objectives: To screen serum molecular markers systematically amid aortic dissection and acute coronary syndrome and to preliminarily identify the pathogenesis of acute aortic dissection. Methods: Related disputes cases of all hospitals were statistically analyzed for the AAD medical disputes ratio, early death ratio and misdiagnosis ratio from the database of Guangdong Province Medical Disputes Coordination Committee from 2013 to 2017. Serum and Aortic tissues samples were respectively quantified by iTRAQ and label-free analysis, further validated by ELISA and protein verified by immunofluorescence and Western blot from AAD and control patients enrolled from the Zhujiang Hospital of Southern Medical University and Guangdong Province people's Hospital from 2016 to 2018. Results: AAD cases ratio accounted for 15.29% in all 150 cardiovascular disputes, 59.26% in all cardiovascular death less than 24 h, and 88.89% in the patients who remained undiagnosed at the time of death, 84 proteins (66 and 18 upregulated and downregulated, respectively) were identified by iTRAQ and 16 proteins (9 and 7 upregulated and downregulated, respectively) by Label-free. Nine proteins (Lumican, FGL1, PI16, MMP9, FBN1, MMP2, VWF, MMRN1, and PF4) related to the pathogenesis of aortic dissection were identified by David /Ease and String techniques as candidate biomarkers for verification test. Four proteins (Lumican, FGL1, PI16, and MMP9) were found to be statistically different after ELISA verification. The expression of FGL1, PI16, and MMP9 proteins was pathologically significantly increased except for Lumican. Histologically, TGF-β1, α-SMA, and Collagen1 were also significantly higher in the aortic group. Conclusion: Lumican, FGL1, PI16, and MMP9 may be potential biomarkers in AAD patients, and the Lumican-mediated TGF-β1 pathway is likely to be involved in the pathogenesis of aortic dissection.

Association of Angiotensin II Type 1 Receptor Agonistic Autoantibodies With Outcomes in Patients With Acute Aortic Dissection

Angiotensin II is significantly associated with the pathogenesis of acute aortic dissection. Angiotensin II type 1 receptor agonistic autoantibodies (AT1-AAs) can mimic the effect of angiotensin II. To investigate the association between AT1-AAs and all-cause and cause-specific mortality risk in patients with acute aortic dissection. A total of 662 patients with clinically suspected aortic dissection from 3 medical centers in Wuhan, China, were enrolled in this cohort study from August 1, 2014, to July 31, 2016. Of these, 315 patients were included in the 3-year follow-up study. Follow-up was mainly performed via telephone interviews and outpatient clinic visits. Data analysis was conducted from March 1 to May 31, 2020. The primary outcomes of interest were all-cause mortality, death due to aortic dissection, and late aortic-related adverse events. The full study cohort included 315 patients with AAD (mean [SD] age, 56.2 [12.7] years; 230 men [73.0%]). Ninety-two patients (29.2%) were positive for AT1-AAs. The mortality of AT1-AA-positive patients was significantly higher than that of AT1-AA-negative patients (40 [43.5%] vs 37 [16.6%]; P < .001). The mortality risk in AT1-AA-positive patients was always significantly higher than that in AT1-AA-negative patients in patients with both type A and type B dissection. Multivariable analysis showed that the risk of AT1-AA-positive patients for type A dissection was significantly higher than that of AT1-AA-negative patients (odds ratio [OR], 1.88; 95% CI, 1.12-3.13; P = .02). The Cox proportional hazards regression model showed a significant increase of all-cause mortality risk (OR, 2.27; 95% CI, 1.44-3.57; P < .001) and late aortic-related adverse events (OR, 1.58; 95% CI, 1.06-2.36; P = .03) among AT1-AA-positive patients during the follow-up period compared with AT1-AA-negative patients. This cohort study first detected AT1-AAs in patients with acute aortic dissection. The presence of AT1-AAs was associated with significantly higher all-cause and cause-specific mortality during a follow-up period of 3 years. The antibodies may be a risk factor for aortic dissection.

Association of Toll-Like Receptor 4 Gene Polymorphisms with Acute Aortic Dissection in a Chinese Han Population

Background Inflammation may be involved in the pathogenesis of acute aortic dissection (AAD). Toll-like receptor 4 (TLR4) is known to play a critical role in regulating the immune and inflammatory processes. To date, the relationship between genetic variation of TLR4 and AAD is far from clear. The purpose of our study was to illustrate the relevance of TLR4 polymorphisms with the susceptibility to AAD. Methods A total of 222 AAD patients and 222 controls were enrolled in this study. Frequency distributions of TLR4 polymorphisms (rs10759932 in the promoter and rs11536889 in the 3′-untranslated region) were determined by the KASP method. Clinical parameters were acquired from subjects' medical records, and serum TLR4 levels were collected from our previously published data. Results We found that rs10759932 polymorphism was associated with a reduced risk of AAD in the overall population (CC vs. TT: OR = 0.393, 95%CI = 0.164‐0.939, P = 0.036; recessive model: OR = 0.439, 95%CI = 0.196‐0.984, P = 0.045) and subgroup analyses stratified by sex. The GC genotype and dominant model of rs11536889 conferred a significantly higher risk of AAD compared with GG genotype in female subjects (GC vs. GG: OR = 3.382, 95%CI = 1.051‐10.885, P = 0.041; dominant model: OR = 3.043, 95%CI = 1.041‐8.900, P = 0.042). In addition, a significant interaction between the rs11536889 recessive model and dyslipidemia was observed for an increased risk of AAD (Pinteraction = 0.038, OR = 15.229) after the adjustment for potential clinical covariates. We also used the false-positive report probability (FPRP) analysis to validate the significant results. Furthermore, rs11536889 polymorphism could affect the maximal aortic diameters of AAD (P = 0.037), while AAD patients carrying CC genotype of rs10759932 showed lower serum TLR4 levels than TT genotype carriers (P = 0.043). Conclusions Our findings provide evidence for the association between TLR4 polymorphisms and AAD susceptibility in a Chinese Han population, which may have some implications for understanding the role of TLR4 in the pathophysiology of AAD.

Integrin α9 is involved in the pathopoiesis of acute aortic dissection via mediating phenotype switch of vascular smooth muscle cell

Acute aortic dissection (AAD) is a devastating disease with high mortality; however, the pathogenic mechanisms of AAD remain poorly understood. Our present study aimed to identify genes associated with AAD and explore the molecular function of candidate genes in the pathogenesis of AAD. We used a whole-genome transcriptional microarray to identify putative AAD genes using ascending aortic tissues from four patients with AAD and four healthy organ donors. The differentially expressed genes were further validated in eight patients with AAD and eight healthy organ donors. Functional assessments were conducted to analyze the effects of the identified AAD genes on the phenotype of aortic vascular smooth muscle cells (VSMCs). The whole-genome transcriptional microarray analysis found 129 dysregulated genes in the ascending aortic tissues of AAD (fold change≥2), which were mainly associated with the focal adhesion pathway and actin cytoskeleton regulation pathway. Among these genes, integrin α9 (ITGA9) was identified to be involved in both pathways and downregulated by 50% in AAD patients. The association of ITGA9 with AAD was confirmed by Western blotting analysis (P = 0.003). Functional studies showed that knocking down ITGA9 in VSMCs resulted in a decrease in contractile markers (SM22α and α-SMA) and an increase in synthetic markers (OPN and SMemb), suggesting that the VSMCs switched from a contractile to a synthetic phenotype. After overexpression of ITGA9 by a recombinant adenovirus vector in VSMCs, SM22α and α-SMA were upregulated, while SMemb was downregulated, indicating a phenotypic switch from the synthetic to contractile phenotype of VSMCs. In conclusion, our study identified ITGA9 as a novel AAD gene. This gene is downregulated in patients with AAD and is involved in the regulation of the phenotypic switch of VSMCs from a contractile to a synthetic phenotype.

MicroRNA microarray analysis to detect biomarkers of aortic dissection from paraffin-embedded tissue samples.

The aim of this study was to explore the differential expression profiles of microRNAs (miRNAs) in paraffin-embedded acute aortic dissection (AAD) tissues to find potential biomarkers for this disease. A total of 92 paraffin-embedded tissue specimens were collected from 92 patients with AAD who underwent surgical replacement. Among these specimens, 54 had partial normal aortic segments (smooth intima surface, non-atherosclerotic lesions) in proximal crevasse of aorta. Samples of these segments were taken 1 cm away from aortic lesions as the control group, after eliminating the tunica adventitia tissues. miRNA expression profiles were obtained by miRNA microarray analysis. Differentially expressed miRNAs were found by comparing the AAD group with the control group and were verified by fluorescence real-time quantitative polymerase chain reaction and by fluorescence in situ hybridization. A total of 71 differentially expressed miRNAs were detected. Twenty-two were up-regulated and 49 were down-regulated. Four up-regulated miRNAs (hsa-miR-636, hsa-miR-142-3p, hsa-miR-425-3p, hsa-miR-191-3p) were selected for validation by real-time fluorescence quantitative polymerase chain reaction and fluorescence in situ hybridization. In the fluorescence real-time quantitative polymerase chain reaction analysis, only hsa-miR-636 showed a statistically significant difference in the AAD versus control comparison (3.3-fold, P = 0.012). The fluorescence in situ hybridization validation showed that the expression level of hsa-miR-636 was significantly increased in the AAD versus control comparison (P < 0.001), with average optical densities of 61.29 ± 16.83 in the AAD group and 9.30 ± 3.98 in the control group. Hsa-miR-636 is involved in the pathogenesis of AAD and may be a potential biomarker for this disease.

TMT-Based Quantitative Proteomic Analysis Identification of Integrin Alpha 3 and Integrin Alpha 5 as Novel Biomarkers in Pathogenesis of Acute Aortic Dissection.

Background Acute aortic dissection (AAD) is a devastating cardiovascular disease with a high rate of disability and mortality. This disease often rapidly progresses to fatal multiple organ hypoperfusion, and the incidence has been increasing in recent years. However, the molecular mechanisms have yet to be clarified. This study is aimed at identifying the differential abundance proteins (DAPs) of aortic arch tissues in patients with AAD by proteomics and select possible proteins involved in AAD pathogenesis. Methods The fresh aortic arch tissues obtained from 5 AAD patients and 1 healthy donor were analyzed by amine-reactive tandem mass tag (TMT) labelling and mass spectrometry; then, the pathological sections of another 10 healthy donors and 20 AAD patients were chosen to verify the proteomic results by immunohistochemistry. Results Of 809 proteins identified by proteomic analysis, 132 differential abundance proteins (DAPs) were screened, of which 100 proteins were significantly downregulated while 32 upregulated. Among 100 downregulated proteins, two proteins with known function, integrin alpha 3 (ITGA-3) and ITGA-5, were selected as target proteins involved in AAD pathogenesis. Two target DAPs were verified by immunohistochemisty, and the results showed that the integrated option density (IOD) of ITGA-3 and ITGA-5 in AAD patients was significantly lower than that in healthy donors, which were consistent with the proteomic results (P < 0.001). Conclusion ITGA-3 and ITGA-5 represent novel biomarkers for the pathogenesis of AAD and might be a therapeutic target in the future.

Febuxostat Pretreatment Attenuates Experimental Aortic Dissection in Mice

Introduction - Acute aortic dissection (AAD) is a life-threatening disease among the elderly. AAD is caused by excessive smooth muscle cell loss, extracellular matrix degradation, and inflammation. Although it was recently reported that reactive oxygen species (ROS), which are generated by various pathways such as through the action of xanthine oxidoreductase (XOR), is associated with AAD pathogenesis,1 the mechanisms underlying AAD are not yet understood. XOR is a molybdopterin-containing enzyme that oxidizes hypoxanthine to xanthine, and subsequently, to uric acid. XOR exists in two interconvertible forms, xanthine oxidase (XO) and xanthine dehydrogenase (XDH), and has been linked to the pathogenesis of cardiovascular disease.2 The objective of this study was to investigate the role of XOR in the pathogenesis of AAD and to evaluate whether ROS inhibition by febuxostat, a highly potent inhibitor of XOR, attenuates the development of AAD. Methods - We used fluorescence immunohistochemistry to assess XOR expression in aortic tissues resected from ten AAD patients and in normal aortic tissues from five autopsy samples. In an experimental aortic dissection model based on spontaneously hyperlipidemic Apobec-1−/−/LDLR−/−mice, the mice were treated with drinking water containing 0.027 mg/mL of febuxostat for seven days before angiotensin II (1000 ng/kg/min) was infused. Results - We revealed enhanced XOR expression in atherosclerotic plaques and the degenerated tunica media in AAD tissues compared to that in control tissues, suggesting that XOR-inhibition is associated with the pathogenesis of AAD. In experimental animal study, febuxostat suppressed significantly mortality caused by aortic dissection and ruptured bleeding. (Fig. 1) Furthermore, aortic architecture was preserved, (Fig. 2A) and ROS activity in the aortic wall and macrophage infiltration to the wall was decreased by febuxostat administration compared to mice that received no treatment (Fig. 2B). Conclusion - Our findings suggest that XOR expression in aortic tissues may promote AAD. These results demonstrate that in the aortic wall, XO-mediated ROS formation is pro-inflammatory and XO inhibition by febuxostat is a potential therapy for AAD.

Regulatory Mechanism of MicroRNA-145 in the Pathogenesis of Acute Aortic Dissection.

PurposePrevious studies have confirmed that microRNAs play important roles in the pathogenesis of acute aortic dissection (AAD). Here, we aimed to explore the role of miR-145 and its regulatory mechanism in the pathogenesis of AAD.Materials and MethodsAAD tissue samples were harvested from patients with aortic dissection and normal donors. Rat aortic vascular smooth muscle cells (VSMCs) were transfected with miR-145 mimic/inhibitor or negative control mimic/inhibitor. Gene and protein expression was measured in human aortic dissection tissue specimens and VSMCs by qRT-PCR and Western blot. Luciferase reporter assay was applied to verify whether connective tissue growth factor (CTGF) was a direct target of miR-145 in VSMCs. Methyl thiazolyl tetrazolium assay was used to detect VSMC viability.ResultsmiR-145 expression was downregulated in aortic dissection tissues and was associated with the survival of patients with AAD. Overexpression of miR-145 promoted VSMC proliferation and inhibited cell apoptosis. Moreover, CTGF, which was increased in aortic dissection tissues, was decreased by miR-145 mimic and increased by miR-145 inhibitor. Furthermore, CTGF was confirmed as a target of miR-145 and could reverse the promotion effect of miR-145 on the progression of AAD.ConclusionmiR-145 suppressed the progression of AAD by targeting CTGF, suggesting that a miR-145/CTGF axis may provide a potential therapeutic target for AAD.

Ectopic Expression of PCSK9 by Smooth Muscle Cells Contributes to Aortic Dissection

Acute aortic dissection (AAD) is a common disease among the elderly. Although several risk factors of AAD have been reported, the molecular mechanism underlying AAD development remains to be elucidated. Proprotein convertase subtilisin/kexin type 9 (PCSK9) increases low-density lipoprotein cholesterol levels in blood by preventing its clearance. Therefore, PCSK9 inhibition is a promising therapeutic approach to treat cardiovascular diseases (CVDs). The objective of this study was to elucidate the role of PCSK9 in the pathogenesis of AAD. We used fluorescence immunohistochemistry to assess PCSK9 expression in aortic tissues resected from 10 AAD patients and in the normal aorta from 5 autopsy samples as well as in spontaneously hyperlipidemic apolipoprotein E-deficient mice used as an experimental AD model. We revealed a characteristic distribution pattern of PCSK9 in atherosclerotic plaques and the degenerated tunica media in AAD tissues, which was rarely observed in normal aortic tissues. Furthermore, PCSK9 was notably expressed around calcification areas formed by vascular smooth muscle cells, especially those of the synthetic phenotype. The results obtained in the animal model were consistent with PCSK9 expression in AAD tissues. Our findings suggest that PCSK9 overexpression in the aorta may promote AAD. This study adds to the growing body of evidence supporting the use of PCSK9 inhibitors for the management of CVDs.

Bindarit reduces the incidence of acute aortic dissection complicated lung injury via modulating NF-κB pathway.

The pathogenesis of acute aortic dissection (AAD) complicated acute lung injury (ALI) is not currently well defined. At present, no effective animal model has been established for AAD complicated ALI, which hinders research and development of an appropriate treatment regimen for the concurrent conditions. The aim of the present study was to evaluate the therapeutic effects of bindarit (Bnd), an indazolic derivative, on the production of monocyte chemoattractant protein (MCP)-1 in angiotensin II (AngII)-induced complicated ALI in rats. An AAD complicated ALI rat model was established using aminopropionitrile (BAPN) and AngII. The pathological features of AAD complicated ALI were assessed via biochemical and histopathological evaluations. AngII-stimulated human pulmonary microvascular endothelial cells (hPMVECs) were used to assess the effects of Bnd on MCP-1 expression. Western blot analysis was performed to analyze the expression of proteins that may be associated with the process. AAD complicated ALI was established following BAPN and AngII interference, and a massive accumulation of macrophages was observed in the lung tissues of the study rats. Bnd was able to significantly attenuate the incidence of AAD complicated ALI (P<0.05), and significantly inhibit the accumulation of macrophages (P<0.05). The overexpression of MCP-1 induced by AngII in hPMVECs was significantly inhibited by Bnd (P<0.05), which may be associated with downregulation of the classical nuclear factor-κB pathway. Bnd was able to attenuate the incidence of AAD complicated ALI, and inhibit the accumulation of macrophages in vivo. These findings provide a basis for future applications of Bnd as part of a therapeutic treatment schedule for aortic dissection complicated lung injury.

Ursodeoxycholic Acid Attenuates Acute Aortic Dissection Formation in Angiotensin II-Infused Apolipoprotein E-Deficient Mice Associated with Reduced ROS and Increased Nrf2 Levels

Background/Aims: Acute aortic dissection (AAD) is characterized by excessive smooth muscle cell (SMC) loss, extracellular matrix (ECM) degradation and inflammation. In response to certain stimulations, oxidative stress is activated and regulates apoptosis and inflammation. Excessive apoptosis promotes aortic inflammation and degeneration, leading to AAD formation. This study aimed to clarify role of oxidative stress in the pathogenesis of AAD and whether the antioxidant ursodeoxycholic acid (UDCA) attenuates AAD formation. Methods: Angiotensin II (Ang II) was infused in 8-months male ApoE^-/- mice for one week to establish a model of AAD. UDCA (10 mg/kg/day) was administered via intragastric gavage for 3 consecutive days before AngII infusion and also during the AngII infusion for another consecutive 7 days. Results: Ang II-infusion resulted in the incidence of AAD at a rate of 35% (13/37) and UDCA markedly reduced the incidence of AAD to 16% (6/37), accompanied with reduced maximal aortic diameter measured at the suprarenal region of the abdominal aorta. Additionally, UDCA pretreatment prevented Ang II induced generations of reactive oxygen species (ROS) and apoptosis of vascular smooth muscle cells (VSMCs) both in vivo and in. vitro Mechanistically, we found UDCA markedly increased Nrf2 expression in VSMCs and prevented Ang II induced expression of NADPH subunits (p47, p67 and gp91) in Nrf2-dependent manner and rescued the activity of redox enzymes (Cu/Zn-SOD, Mn-SOD and CAT), thereby inhibiting apoptosis of VSMCs. Conclusion: These results demonstrate that UDCA prevented AAD formation by reducing apoptosis of VSMCs caused by oxidative stress in Nrf2 dependent manner and suggest that UDCA might have clinical potential to suppress AAD formation.

Tenascin C protects aorta from acute dissection in mice

Acute aortic dissection (AAD) is caused by the disruption of intimomedial layer of the aortic walls, which is immediately life-threatening. Although recent studies indicate the importance of proinflammatory response in pathogenesis of AAD, the mechanism to keep the destructive inflammatory response in check is unknown. Here, we report that induction of tenascin-C (TNC) is a stress-evoked protective mechanism against the acute hemodynamic and humoral stress in aorta. Periaortic application of CaCl2 caused stiffening of abdominal aorta, which augmented the hemodynamic stress and TNC induction in suprarenal aorta by angiotensin II infusion. Deletion of Tnc gene rendered mice susceptible to AAD development upon the aortic stress, which was accompanied by impaired TGFβ signaling, insufficient induction of extracellular matrix proteins and exaggerated proinflammatory response. Thus, TNC works as a stress-evoked molecular damper to maintain the aortic integrity under the acute stress.

Pathogenesis of Acute Aortic Dissection: A Finite Element Stress Analysis

Type A and type B aortic dissections typically result from intimal tears above the sinotubular junction and distal to the left subclavian artery (LSA) ostium, respectively. We hypothesized that this pathology results from elevated pressure-induced regional wall stress. We identified 47 individuals with normal thoracic aortas by electrocardiogram-gated computed tomography angiography. The thoracic aorta was segmented, reconstructed, and triangulated to create a geometric mesh. Finite element analysis using a systolic pressure load of 120 mm Hg was performed to predict regional thoracic aortic wall stress. There were local maxima of wall stress above the sinotubular junction in the ascending aorta and distal to the ostia of the supraaortic vessels, including the LSA, in the aortic arch. No local maximum of wall stress was found in the descending thoracic aorta. Comparison of the mean peak wall stress above the sinotubular junction (0.43 ± 0.07 MPa), distal to the LSA (0.21 ± 0.07 MPa), and in the descending thoracic aorta (0.06 ± 0.01 MPa) showed a significant effect for wall stress by aortic region (p < 0.001). In the normal thoracic aorta, there are peaks in wall stress above the sinotubular junction and distal to the LSA ostium. This stress distribution may contribute to the pathogenesis of aortic dissections, given their colocalization. Future investigations to determine the utility of image-derived biomechanical calculations in predicting aortic dissection are warranted, and therapies designed to reduce the pressure load-induced wall stress in the thoracic aorta are rational.

Pathogenesis of Acute Aortic Dissection: A Finite Element Stress Analysis

Pathogenesis of Acute Aortic Dissection: A Finite Element Stress Analysis