Neutrophil-Derived Matrix Metalloproteinase 9 Triggers Acute Aortic Dissection

ACE2 deficiency inhibits thoracic aortic dissection by enhancing SIRT3 mediated inhibition of inflammation and VSCMs phenotypic switch

BACKGROUND

Thoracic aortic dissection (TAD) is an irreversible cardiovascular disorder with high mortality and morbidity. However, the molecular mechanisms remain elusive. Thus, identifying an effective therapeutic target to prevent TAD is especially critical. The purpose of this study is to elucidate the potential mechanism of inflammation and vascular smooth muscle cell (VSMCs) phenotypic switch in β-aminopropionitrile fumarate (BAPN)-induced TAD.

METHODS

A mouse model of TAD induced by BAPN and IL-1β -stimulated HVSMCs in vivo and in vitro models, respectively. ACE2 Knockdown mice treated with BAPN or without, and the TAD mouse model was treated with or without AAV-ACE2. Transthoracic ultrasound was conducted for assessment the maximum internal diameter of the thoracic aorta arch. RNA sequencing analysis was performed to recapitulate transcriptome profile changes. Western blot were used to detect the expression of MMP2, MMP9, ACE2, SIRT3, OPN, SM22α and other inflammatory markers. The circulating levels of ACE2 was measured by ELISA assay. Histological changes of thoracic aorta tissues were assessed by H&E, EVG and IHC analysis.

RESULTS

We found that circulating levels of and the protein levels of ACE2 were increased in the TAD mouse model and in patients with TAD. For further evidence, ACE2 deficiency decelerated the formation of TAD. However, overexpression of ACE2 aggravated BAPN-induced aortic injury and VSMCs phenotypic switch via lowered SIRT3 expression and elevated inflammatory cytokine expression.

CONCLUSION

ACE2 deficiency prevented the development of TAD by inhibiting inflammation and VSMCs phenotypic switch in a SIRT3-dependent manner, suggesting that the ACE2/SIRT3 signaling pathway played a pivotal role in the pathological process of TAD and might be a potential therapeutical target.

Structural reconstruction of mouse acute aortic dissection by intravenously administered human Muse cells without immunosuppression

BACKGROUND

Stanford type B-acute aortic dissection (type B-AAD) is often life-threatening without invasive surgery. Multilineage-differentiating stress enduring cell (Muse cells), which comprise several percent of mesenchymal stem cells (MSCs), are endogenous pluripotent-like stem cells that selectively home to damaged tissue and replace damaged/apoptotic cells by in-vivo differentiation.

METHODS

Mortality, aortic diameter expansion, cell localization, cell differentiation, and inflammation of the dissected aorta were evaluated in type B-AAD model mice intravenously injected with human-Muse cells, -elastin-knockdown (KD)-Muse cells, -human leukocyte antigen-G (HLA-G)-KD-Muse cells, or MSCs, all without immunosuppressant.

RESULTS

Here, we show the Muse (50,000 cells) group has a lower incidence of aortic rupture and mortality of AAD compared with the MSC-50K (50,000 human-MSCs) and vehicle groups. Spectrum computed tomography in-vivo dynamics and 3-dimensional histologic analyses demonstrate that Muse cells more effectively home to the AAD tissue and survive for 8 weeks in the Muse group than in the MSC-750K (750,000 human-MSCs containing 50,000 Muse cells) group. Homing of Muse cells is impeded in the HLA-G-KD-Muse (50,000 cells) group. Differentiation of homed Muse cells into CD31(+) and alpha-smooth muscle actin (+) cells, production and reorganization of elastic fibers in the AAD tissue, and suppression of diameter expansion are greater in the Muse group than in the MSC-750K and elastin-KD-Muse (50,000 cells) groups.

CONCLUSIONS

Intravenously administered Muse cells reconstruct the dissected aorta and improve mortality and diameter enlargement rates. Moreover, small doses of purified Muse cells are more effective than large doses of MSCs. HLA-G is suggested to contribute to the successful survival and homing of Muse cells.

Matrix metalloproteinases in aortic dissection

Aortic dissection, characterized by a high immediate mortality, is primarily caused by excessive bleeding within the walls of the aorta or a severe tear within the intimal layer of the aorta. Inflammation, as well as oxidative stress and the degradation of extracellular matrix (ECM), are significant factors in the development and occurrence of aortic dissection. Matrix metalloproteinases (MMPs) are pivotal enzymes responsible for degrading the ECM. Inflammatory factors and oxidants can interact with MMPs, indicating the potential significance of MMPs in aortic dissection. A substantial body of evidence indicates that numerous MMPs are significantly upregulated in aortic dissection, playing a critical role in ECM degradation and the pathogenesis of aortic dissection. Furthermore, targeting these enzymes has demonstrated potential in facilitating ECM restoration and reducing the incidence of aortic dissection. This review initially provides a brief overview of MMP biology before delving into their expression patterns, regulatory mechanisms, and therapeutic applications in aortic dissection. A profound comprehension of the catabolic pathways associated with aortic dissection is imperative for the future development of potential preventive or therapeutic bio-interventions for aortic dissection.

Gasdermin D deficiency attenuates development of ascending aortic dissections in a novel mouse model

Background

Thoracic aortic dissection (TAD) is a silent killer. Approximately two-thirds of the cases occur in the ascending aorta (i.e. type A dissection) and majority of them are unrelated to genetic mutations. However, animal models of spontaneous type A dissection are not widely available. In the present study, a novel mouse TAD model was created. Further, the role of gasdermin D (GSDMD) in TAD development was evaluated.

Methods

TADs were created by treating ascending aorta of adult mice (C57BL/6J) with active elastase (40.0 U/ml) and β-aminopropionitrile (Act E+BAPN). The temporal progress of the TAD pathology was rigorously characterized by histological evaluation and scanning electron microscopy, while potential mechanisms explored with bulk RNA sequencing of specimens collected at multiple timepoints. With this novel TAD model, further experiments were performed with Gsdmd -/- mice to evaluate its impact on TAD formation.

Results

The ascending aorta challenged with Act E+BAPN developed pathology characterized by an early onset of intimomedial tears (complete penetration) and intramural hematoma, followed by progressive medial loss and aortic dilation. Ingenuity Pathway Analysis and functional annotation of differentially expressed genes suggested that a unique inflammatory micro-environment, rather than general inflammation, promoted the onset of TADs by specifically recruiting neutrophils to the aortic wall, while the pathology at the advanced stage was driven by T-cell mediated immune injury. Gsdmd -/- attenuated medial loss, adventitial fibrosis, and dilation of TADs. This protective effect was associated with a reduced number of TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) positive cells and T-cells in TADs.

Conclusions

A novel mouse TAD model was created in the ascending aorta. It produces a unique microenvironment to activate different immune cell subsets, promoting onset and subsequent remodeling of TADs. Consistently, Gsdmd -/- attenuates TAD development, with modulation of cell death and T-cell response likely acting as the underlying mechanism.

S-adenosyl-L-methionine supplementation alleviates aortic dissection by decreasing inflammatory infiltration

Methionine, an indispensable amino acid crucial for dietary balance, intricately governs metabolic pathways. Disruption in its equilibrium has the potential to heighten homocysteine levels in both plasma and tissues, posing a conceivable risk of inducing inflammation and detriment to the integrity of vascular endothelial cells. The intricate interplay between methionine metabolism, with a specific focus on S-adenosyl-L-methionine (SAM), and the onset of thoracic aortic dissection (TAD) remains enigmatic despite acknowledging the pivotal role of inflammation in this vascular condition. In an established murine model induced by β-aminopropionitrile monofumarate (BAPN), we delved into the repercussions of supplementing with S-adenosyl-L-methionine (SAM) on the progression of TAD. Our observations uncovered a noteworthy improvement in aortic dissection and rupture rates, accompanied by a marked reduction in mortality upon SAM supplementation. Notably, SAM supplementation exhibited a considerable protective effect against BAPN-induced degradation of elastin and the extracellular matrix. Furthermore, SAM supplementation demonstrated a robust inhibitory influence on the infiltration of immune cells, particularly neutrophils and macrophages. It also manifested a notable reduction in the inflammatory polarization of macrophages, evident through diminished accumulation of MHC-IIhigh macrophages and reduced expression of inflammatory cytokines such as IL1β and TNFα in macrophages. Simultaneously, SAM supplementation exerted a suppressive effect on the activation of CD4 + and CD8 + T cells within the aorta. This was evidenced by an elevated proportion of CD44- CD62L + naïve T cells and a concurrent decrease in CD44 + CD62L- effector T cells. In summary, our findings strongly suggest that the supplementation of SAM exhibits remarkable efficacy in alleviating BAPN-induced aortic inflammation, consequently impeding the progression of thoracic aortic dissection.

Complement C3a/C3aR inhibition alleviates the formation of aortic aneurysm in Marfan syndrome mice

Mutations in fibrillin 1 (FBN1) is the main cause of Marfan syndrome (MFS) with thoracic aortic aneurysm (TAA) as the main complication. Activation of the complement system plays a key role in the formation of thoracic and abdominal aortic aneurysms. However, the role of the complement system in MFS-associated aortic aneurysms remains unclear. In this study, we observed increased levels of complement C3a and C5a in the plasma of MFS patients and mouse, and the increased deposition of the activated complement system product C3b/iC3b was also observed in the elastic fiber rupture zone of 3-month-old MFS mice. The expression of C3a receptor (C3aR) was increased in MFS aortas, and recombinant C3a promoted the expression of cytokines in macrophages. The administration of a C3aR antagonist (C3aRA) attenuated the development of thoracic aortic aneurysms in MFS mice. The increased inflammation response and matrix metalloproteinases activities were also attenuated by C3aRA treatment in MFS mice. Therefore, these findings indicate that the complement C3a/C3aR inhibition alleviates the formation of aortic aneurysm in Marfan syndrome mice.

Effect of FluoRoquinolones on Aortic Growth, aortic stIffness and wave refLEctionS (FRAGILES study)

Background: The widespread use of fluoroquinolones has been associated with the formation, dissection, and rupture of aortic aneurysms. Arterial biomarkers are established predictors of cardiovascular events. The present study was designed to investigate the effect of quinolones on arterial stiffness and aortic size for the first time. Methods: We studied 28 subjects receiving short-term (<15 days) antibiotic therapy involving quinolones and 27 age- and sex-matched subjects receiving an alternative to quinolone antibiotics. The follow-up period was approximately 2 months. The study's primary endpoint was the carotid-femoral pulse wave velocity (cfPWV) difference between the two groups 2 months after therapy initiation. Secondary endpoints were the augmentation index corrected for heart rate (AIx@75) and sonographically assessed aortic diameters 2 months after the initial treatment. Results: Subjects had similar values of arterial biomarkers, blood pressure measurements, and aortic diameters at baseline. At follow-up, no significant change was observed between the two groups regarding the hemodynamic parameters and arterial biomarkers (p > 0.05 for all), i.e., cfPWV (7.9 ± 2.6 m/s for the control group vs. 8.1 ± 2.4 m/s for the fluoroquinolones group; p = 0.79), AIx@75 (22.6 ± 9.0% for the control group vs. 26.6 ± 8.1% for the fluoroquinolones group; p = 0.09), and aortic diameters. Conclusions: To our knowledge, FRAGILES is the first study to provide insights into the possible effects of fluoroquinolones on arterial biomarkers, showing that, at least in the short term, treatment with fluoroquinolones does not affect aortic function and diameter.

Elucidating thoracic aortic dissection pathogenesis: The interplay of m1A-related gene expressions and miR-16-5p/YTHDC1 Axis in NLRP3-dependent pyroptosis

The underlying molecular mechanisms of thoracic aortic dissection (TAD) remain incompletely understood. Recent insights into RNA methylation and microRNA-mediated gene regulation offer new avenues for exploring how these processes contribute to the pathophysiology of TAD, particularly through the modulation of pyroptosis and smooth muscle cell viability. This research aimed to elucidate the interplay of m1A-related gene expressions and miR-16-5p/YTHDC1 Axis in NLRP3-dependent pyroptosis, a mechanism implicated in the pathogenesis of TAD. We collected tissue samples from 28 human TAD patients and 8 healthy aortic group, as well as utilized a mouse model to replicate the disease. A combination of computational, in vitro, and in vivo methods was applied, including CIBERSORTx analysis, Pearson correlation, gene transfection using antagomiR-16-5p, siRNA, and several staining as well as cell culture techniques. Our analysis indicated two differentially expressed genes, ALKBH2 and YTHDC1. We found significant upregulation of has-miR-16-5p and downregulation of YTHDC1 at mRNA level in AD samples. Immune cell infiltration in TAD samples was examined using the CIBERSORTx database. We confirmed that YTHDC1 was a target of miR-16-5p, as evidenced by an inhibitory effect on luciferase activity. Inhibition of miR-16-5p enhanced SMC proliferation and promoted cell viability whilst downregulating NLRP3-pyroptosis. YTHDC1 expression was increased, and NLRP3-pyroptosis expressions were inhibited, suggesting miR-16-5p/YTHDC1 axis may involve the NLRP3-pyroptosis of the SMC. In vivo analyses confirmed the prevention of NLRP3-pyroptosis in middle layer of the thoracic aorta, implying that the miR-16-5p/YTHDC1 axis regulated SMC proliferation via NLRP3-pyroptosis signaling. Our findings underscored the anti-pyroptotic role of miR-16-5p/YTHDC1 axis in the pathogenesis of TAD, suggesting a potential therapeutic strategy via targeting YTHDC1 and suppressing miR-16-5p to inhibit NLRP3-dependent pyroptosis. Although further investigation is needed, these results relating to SMC proliferation are a significant step forward in understanding TAD.

Intense impact of IL-1β expressing inflammatory macrophages in acute aortic dissection

There is no treatment for acute aortic dissection (AAD) targeting inflammatory cells. We aimed to identify the new therapeutic targets associated with inflammatory cells. We characterized the specific distribution of myeloid cells of both human type A AAD samples and a murine AAD model generated using angiotensin II (ANGII) and β-aminopropionitrile (BAPN) by single-cell RNA sequencing (scRNA-seq). We also examined the effect of an anti-interleukin-1β (IL-1β) antibody in the murine AAD model. IL1B+ inflammatory macrophages and classical monocytes were increased in human AAD samples. Trajectory analysis demonstrated that IL1B+ inflammatory macrophages differentiated from S100A8/9/12+ classical monocytes uniquely observed in the aorta of AAD. We found increased infiltration of neutrophils and monocytes with the expression of inflammatory cytokines in the aorta and accumulation of inflammatory macrophages before the onset of macroscopic AAD in the murine AAD model. In blocking experiments using an anti-IL-1β antibody, it improved survival of murine AAD model by preventing elastin degradation. We observed the accumulation of inflammatory macrophages expressing IL-1β in both human AAD samples and in a murine AAD model. Anti-IL-1β antibody could improve the mortality rate in mice, suggesting that it may be a treatment option for AAD.

Acute aortic catastrophe caused by cardiovascular oncological manipulation by tyrosine kinase inhibitors with immune checkpoint blockades: a case report and literature review

Background

Tyrosine kinase inhibitors targeting the vascular endothelial growth factor (VEGF) inhibitor pathway with immune checkpoint blockade have shown promising outcomes in managing metastatic renal cancer. However, they increase the risk of a person developing high blood pressure and cardiovascular complications.

Case summary

In this study, we report the case of a 73-year-old woman on axitinib and pembrolizumab for her Stage 4 renal cell carcinoma. She presented with intractable chest pain and high systolic blood pressure, not responding to opiates. Her computed tomography angiography results showed an acute intra-mural haematoma with a rupture in the descending thoracic aorta. She underwent emergency thoracic endovascular aortic repair. Post-operatively, she recovered fully without any neurological or cardiovascular issues.

Discussion

The severity of cardiovascular haemodynamic complications arising from the consumption of VEGF inhibitors and from immunotherapy and the lack of anti-hypertensive strategies to adequately manage such events require an unequivocal and urgent assessment of their cardiovascular safety. This case highlights the crucial role of cardiovascular oncology in managing such acute aortic catastrophes.

Biomarkers in aortic dissection: Diagnostic and prognostic value from clinical research

ABSTRACT

Aortic dissection is a life-threatening condition for which diagnosis mainly relies on imaging examinations, while reliable biomarkers to detect or monitor are still under investigation. Recent advances in technologies provide an unprecedented opportunity to yield the identification of clinically valuable biomarkers, including proteins, ribonucleic acids (RNAs), and deoxyribonucleic acids (DNAs), for early detection of pathological changes in susceptible patients, rapid diagnosis at the bedside after onset, and a superior therapeutic regimen primarily within the concept of personalized and tailored endovascular therapy for aortic dissection.

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.

Integrative analysis reveals chemokines CCL2 and CXCL5 mediated shear stress-induced aortic dissection formation

Background

Aortic dissection (AD) is a critical emergency in cardiovascular disease. AD occurs only in specific sites of the aorta, and the variation of shear stress in different aortic segments is a possible cause not reported. This study investigated the key molecules involved in shear stress-induced AD through quantitative bioinformatic analysis of a public RNA sequencing database and clinical tissue sample validation.

Methods

Gene expression data from the GSE153434, GSE147026, and GSE52093 datasets were downloaded from the Gene Expression Omnibus. Next, differently expressed genes (DEGs) in each dataset were identified and integrated to identify common AD DEGs. STRING, Cytoscape, and MCODE were used to identify hub genes and crucial clustering modules, and Connectivity Map (CMap) was used to identify positive and negative agents. The same procedure was performed for the GSE160611 dataset to obtain shear stress-induced human aortic endothelial cell (HAEC) DEGs. After the integration of these two DEGs sets to identify shear stress-associated hub DEGs in AD, Gene Ontology Enrichment Analysis was performed. The common chemokine receptors and ligands in AD were identified by analyzing AD's three RNA sequencing datasets. Their origin was verified by analyzing AD single-cell sequencing data and validated by immunoblotting and immunofluorescence.

Results

We identified 100 down-regulated and 50 up-regulated AD common DEGs. Enrichment results showed that common DEGs were closely related to blood vessel morphogenesis, muscle structure development, muscle tissue development, and chemotaxis. Among those DEGs, MYC, CCL2, and SPP1 are the three molecules with the highest degree. A crucial cluster of 15 genes was identified using MCODE, which contained inflammation-related genes with elevated expression and muscle cell-related genes with decreased expression, and CCL2 is central to immune-related genes. CMap confirmed MEK inhibitors and ALK inhibitors as possible therapeutic agents for AD. Moreover, 366 shear stress-associated DEGs in HAEC were identified in the GSE160611 dataset. After taking the intersection, we identified five shear stress-associated hub DEGs in AD (ANGPTL4, SNAI2, CCL2, GADD45B, and PROM1), and the enrichment analysis indicated they were related to the endothelial cell apoptotic process. Chemokine CCL2 was the molecule with a high degree in both DEG sets. Besides CCL2, CXCL5 was the only chemokine ligand differentially expressed in the three datasets. Additionally, immunoblotting confirmed the increased expression of CCL2 and CXCL5 in clinical tissue samples. Further research at the single-cell level revealed that CCL2 has multiple origins, and CXCL5 is macrophage-derived.

Conclusion

Through integrative analysis, we identified core common AD DEGs and possible therapeutic agents based on these DEGs. We elucidated that the chemokine CCL2 and CXCL5-mediated "Endothelial-Monocyte-Neutrophil" axis may contribute to the development of shear stress-induced AD. These findings provide possible therapeutic targets for the prevention and treatment of AD.

In Vivo Efficacy of an Adhesive Bioresorbable Patch to Treat Aortic Dissections

Endovascular repair of aortic dissection still presents significant limitations. Preserving the mechanical and biological properties set by the aortic microstructure is critical to the success of implantable grafts. In this paper, we present the performance of an adhesive bioresorbable patch designed to cover the entry tear of aortic dissections. We demonstrate the power of using a biomimetic scaffold in a vascular environment.

Spontaneous coronary artery dissection in women with acute myocardial infarction: is there a new role for autoimmunity?

AIMS

Spontaneous coronary artery dissection (SCAD) is an uncommon cause of acute myocardial infarction in women and has an unclear pathophysiology. Autoantibodies (AAs) targeting angiotensin-II receptor type 1 (AT1R) and endothelin-1 receptor type A (ETAR) have known detrimental effects on endothelial function. We investigated the prevalence of these AAs in SCAD-affected female patients.

METHODS AND RESULTS

Female patients diagnosed at coronary angiography with myocardial infarction and SCAD were consecutively enrolled. Autoantibodies targeting angiotensin-II receptor type 1 and ETAR-AA titres and seropositivity prevalence were compared between SCAD patients, ST-elevation myocardial infarction (STEMI) patients, and healthy women. Ten women with SCAD and 20 age-matched controls (10 women with STEMI and 10 healthy women) were included. Six out of 10 (60%) women with myocardial infarction and SCAD were seropositive for AT1R-AAs and ETAR-AAs. In contrast, only one (10%) healthy woman and one (10%) STEMI patient were seropositive for AT1R-AAs (P = 0.03 and P = 0.03, respectively). One STEMI patient was seropositive for ETAR-AAs, while none of the healthy women was found to be seropositive (P = 0.03 and P = 0.01, respectively). The median AA titre was significantly higher in SCAD patients than in healthy women (P = 0.01 for AT1R-AAs; P = 0.02 for ETAR-AAs) and STEMI patients (P < 0.001 for AT1R-AAs; P = 0.002 for ETAR-AAs).

CONCLUSION

Autoantibodies targeting angiotensin-II receptor type 1 and ETAR-AA seropositivity is significantly higher in SCAD women with myocardial infarction than in healthy women or female patients with STEMI. Our findings, corroborated by previous data in the literature and biological plausibility, suggest a possible role for AT1R-AAs and ETAR-AAs in the pathophysiology of SCAD in women with acute myocardial infarction and should warrant further studies with larger sample sizes.

Single Nucleotide Polymorphisms Mutation of Tropoelastin Gene Affects Tropoelastin mRNA and Elastin Expressions in Human Aortic Smooth Muscle Cells

We aimed to explore the effects of single nucleotide polymorphisms (SNPs) in tropoelastin gene on tropoelastin mRNA and elastin expressions in human aortic smooth muscle cells (HASMCs). Two SNP loci, rs2071307 (G/A) and rs1785598 (G/C), were selected to construct recombinant lentivirus vectors carrying wild-type and mutant tropoelastin gene. Recombinant plasmids including pWSLV-02-ELN, pWSLV-02-ELN-mut1, and pWSLV-02-ELN-mut2 were constructed, before being amplified by polymerase chain reaction (PCR) and sequenced. The prepared plasmids and the packaging plasmids (pVSV-G and psPAX2) were cotransfected into HEK293T cells to obtain recombinant lentiviruses carrying tropoelastin gene. Afterward, HASMCs were infected with recombinant lentiviruses, and the positive cells sorted by flow cytometry were amplified. Four stable HASMCs cell lines including pWSLV-02-ELN, pWSLV-02-ELN-mut1, pWSLV-02-ELN-mut2, and pWSLV-02 vector were constructed. The expressions of tropoelastin mRNA and elastin in HASMCs were detected by real-time quantitative reverse transcription-PCR and western blot, respectively. Recombinant plasmids including pWSLV-02-ELN-mut1, pWSLV-02-ELN-mut2, and pWSLV-02-ELN were successfully constructed. Recombinant lentiviruses carrying tropoelastin gene were obtained via lentivirus packaging. After infection for 24 h, 3 days and 5 days in HASMCs, tropoelastin mRNA expressions in pWSLV-02-ELN-mut1 and pWSLV-02-ELN-mut2 groups were significantly lower than that of pWSLV-02-ELN group. Besides, after infection for 24 h, 3 days, and 5 days, elastin levels in pWSLV-02-ELN-mut1 and pWSLV-02-ELN-mut2 groups were significantly lower than that in pWSLV-02-ELN group. In conclusion, SNPs mutation of tropoelastin gene affected the expression of tropoelastin mRNA and elastin, suggesting that the polymorphisms of rs2071307 and rs17855988 in tropoelastin gene might be important factors for AD development.

Delamination Strength and Elastin Interlaminar Fibers Decrease with the Development of Aortic Dissection in Model Rats

Aortic dissection (AD) is a life-threatening tear of the vascular tissue with creation of a false lumen. To explore the mechanism underlying this tissue tear, this study investigated the delamination strength of AD model rats and the histological composition of the aorta at various stages of AD development. SD rats were administrated beta-amino propionitrile for 0 (Control), 3 (Pre-dissection), and 6 (Dissection) weeks. The thoracic aorta was harvested at 10-11 weeks of age. The Dissection group exclusively showed AD at the ascending aorta. The delamination strength, a force that separates the aorta in the radial direction, of the descending aorta decreased significantly in the order of the Control, Pre-dissection, and Dissection groups. A quantitative histological analysis of the aortic tissue demonstrated that, compared with the Control group, the area fraction of collagen was significantly higher in the Pre-dissection and Dissection groups and that of elastin was significantly lower in the Dissection group. The area fraction of the elastin fibers between the elastic laminas (interlaminar fibers) was significantly decreased in the order of the Control, Pre-dissection, and Dissection groups. Histological changes of the aortic tissue, perhaps a reduction in interlaminar fibers mainly aligned in the radial direction, decreased delamination strength, thereby causing AD.

Causal Role for Neutrophil Elastase in Thoracic Aortic Dissection in Mice

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Clinical analysis of 908 patients with aortic dissection under different Stanford types: A cross-sectional study

This study aims to investigate the difference of clinical characteristics and risk factors in aortic dissection (AD) of patients with 2 Stanford subtypes. A retrospective analysis was conducted on 908 patients admitted to Tongji Hospital from July 2019 to January 2021, and the aortic computed tomography angiography was used to clearly diagnose the artery dissection. Patient basic information as well as blood test indicators containing leukocytes, neutrophils, lymphocytes, hemoglobin, myoglobin, hypersensitive cardiac troponin, γ-glutamyl transferase, total cholesterol, triglyceride, high density lipoprotein, low density lipoprotein, ultrasensitive C-reactive protein, glucose were recorded and analyzed. There was no significant difference in gender, heart rate, smoking history, hypertension history and diabetes history between the 2 groups (P > .05), however, compared with type A patients, type B patients were older, and had a significantly higher frequency of alcohol consumption (P < .05); On laboratory tests, type A patients had significantly higher mean leukocytes and neutrophils (P < .05), and significantly lower frequency of reduced hemoglobin than type B patients (P < .05), although there was no statistical difference in lymphocyte, γ-glutamyl transferase, total cholesterol, triglyceride, high density lipoprotein, low density lipoprotein and glucose counts between the 2 groups. Additionally, type A patients had a significantly higher number of abnormal myoglobin, hypersensitive cardiac troponin and ultrasensitive C-reactive protein test results than type B patients (P < .05). The receiver operating characteristic curve analysis showed that the area under the curve for each parameter was 0.605 (0.538-0.673) for hemoglobin, 0.610 (0.543-0.677) for leukocytes and 0.627 (0.561-0.693) for neutrophils. Understanding the relevant clinical indicators and risk factors of patients with different types of AD can provide a new perspective to assist the classification and diagnosis of AD and a basis for effective and rational treatment.

The Prognostic Significance of Leukocyte Count on All-Cause and Cardiovascular Disease Mortality: A Systematic Review and Meta-Analysis

White blood cells (WBCs) act as mediators of inflammatory responses and are commonly measured in hospitals. Although several studies have reported a relation between WBC count and mortality, no systematic review or meta-analysis has been conducted. This study aimed to identify an association between WBC count and mortality. We conducted a systematic search on Embase using keywords such as "white blood cell" and "mortality." We analyzed the hazard ratios (HRs) for WBC count of 1.0 × 109 cells/L regarding 2 criteria: the cause of mortality and the follow-up period. A total of 13 of 222 articles comprising a total of 62,904 participants were included in this study, meeting the criteria set. A positive association was observed between WBC count and mortality, as indicated by an HR of 1.10 (95% confidence interval [CI] 1.08 to 1.13). In additionally, WBC count emerged as a significant predictor of mortality in both groups, with an HR of 1.10 (95% CI 1.07 to 1.12) for patients with cardiovascular disease and an HR of 1.12 (95% CI 1.07 to 1.17) for the general population or patients with COVID-19. Furthermore, a higher WBC count demonstrated a significant association with long-term all-cause mortality (HR 1.09, 95% CI 1.07 to 1.12) and long-term cardiovascular mortality (HR 1.05, 95% CI 1.02 to 1.07). Similarly, a significant association was found between higher WBC count and short-term all-cause mortality (HR 1.12, 95% CI 1.09 to 1.16) and cardiovascular mortality (HR 1.12, 95% CI 1.07 to 1.17). Further research is necessary to explore the relation between WBC count and disease progression or death and to establish causality between elevated WBC count and disease progression.

Platelets reprogram monocyte functions by secreting MMP-9 to benefit postoperative outcomes following acute aortic dissection

Platelets have a great ability to modulate immune responses. Monocyte-platelet aggregates (MPAs) are associated with the pathogenesis of cardiac disease. Notably, a low preoperative platelet count often indicates poor postoperative recovery following acute aortic dissection (AAD). The functions of platelets and MPAs in AAD, however, remain poorly understood. We found that, despite decreased platelet counts, platelets were also activated in AAD patients, with significant alterations in immune-modulating mediators. Of interest, monocytes in AAD patients had a suppressed immune status, which was correlated with poor outcomes following surgery. Interestingly, platelets preferentially aggregated with monocytes, and the levels of MPAs were related to recovery after surgical repair in AAD patients. Platelets restored suppressed monocyte functions in AAD patients by forming aggregates and partly by secreting matrix metalloproteinase-9 (MMP-9). Thus, the results point to a previously unknown mechanism for platelets involving monocyte reprogramming, which may improve postoperative outcomes following complex cardiovascular surgery.

Identification of key biomarkers and immune infiltration in the thoracic acute aortic dissection by bioinformatics analysis

BACKGROUND

Thoracic acute aortic dissection (TAAD), one of the most fatal cardiovascular diseases, leads to sudden death, however, its mechanism remains unclear.

METHODS

Three Gene Expression Omnibus datasets were employed to detect differentially expressed genes (DEGs). A similar function and co-expression network was identified by weighted gene co-expression network analysis. The least absolute shrinkage and selection operator, random forest, and support vector machines-recursive feature elimination were utilized to filter diagnostic TAAD markers, and then screened markers were validated by quantitative real-time PCR and another independent dataset. CIBERSORT was deployed to analyze and evaluate immune cell infiltration in TAAD tissues.

RESULTS

Twenty-five DEGs were identified and narrowed down to three after screening. Finally, two genes, SLC11A1 and FGL2, were verified by another dataset and qRT-PCR. Function analysis revealed that SLC11A1 and FGL2 play significant roles in immune-inflammatory responses.

CONCLUSION

SLC11A1 and FGL2 are differently expressed in aortic dissection and may be involved in immune-inflammatory responses.

The mechanism and therapy of aortic aneurysms

Aortic aneurysm is a chronic aortic disease affected by many factors. Although it is generally asymptomatic, it poses a significant threat to human life due to a high risk of rupture. Because of its strong concealment, it is difficult to diagnose the disease in the early stage. At present, there are no effective drugs for the treatment of aneurysms. Surgical intervention and endovascular treatment are the only therapies. Although current studies have discovered that inflammatory responses as well as the production and activation of various proteases promote aortic aneurysm, the specific mechanisms remain unclear. Researchers are further exploring the pathogenesis of aneurysms to find new targets for diagnosis and treatment. To better understand aortic aneurysm, this review elaborates on the discovery history of aortic aneurysm, main classification and clinical manifestations, related molecular mechanisms, clinical cohort studies and animal models, with the ultimate goal of providing insights into the treatment of this devastating disease. The underlying problem with aneurysm disease is weakening of the aortic wall, leading to progressive dilation. If not treated in time, the aortic aneurysm eventually ruptures. An aortic aneurysm is a local enlargement of an artery caused by a weakening of the aortic wall. The disease is usually asymptomatic but leads to high mortality due to the risk of artery rupture.

Perioperative Risk Factors for Post-operative Pneumonia after Type A Acute Aortic Dissection Surgery

OBJECTIVE

Type A acute aortic dissection (TAAAD) is a dangerous and complicated condition with a high death rate before hospital treatment. Patients who are fortunate to receive prompt surgical treatment still face high in-hospital mortality. A series of post-operative complications further affects the prognosis. Post-operative pneumonia (POP) also leads to great morbidity and mortality. This study aimed to identify the prevalence as well as the risk factors for POP in TAAAD patients and offer references for clinical decisions to further improve the prognosis of patients who survived the surgical procedure.

METHODS

The study enrolled 89 TAAAD patients who underwent surgical treatment in Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei province, China from December 2020 to July 2021 and analyzed the perioperative data and outcomes of these patients. Logistic regression analyses were used to identify the risk factors for POP.

RESULTS

In the study, 31.5% of patients developed POP. Patients with POP had higher proportions of severe oxygenation damage, pneumothorax, reintubation, tracheotomy, renal replacement therapy, arrhythmia, gastrointestinal bleeding, and longer duration of mechanical ventilation, fever, ICU stay, and length of stay (all with P<0.05). The in-hospital mortality was 2.3%. Smoking, preoperative white blood cells, and intraoperative transfusion were the independent risk factors for POP in TAAAD.

CONCLUSION

Patients who underwent TAAAD surgery suffered poorer outcomes when they developed POP. Furthermore, patients with risk factors should be treated with caution.

Targeting endothelial tight junctions to predict and protect thoracic aortic aneurysm and dissection

AIMS

Whether changes in endothelial tight junctions (TJs) lead to the formation of thoracic aortic aneurysm and dissection (TAAD) and serve as an early indicator and therapeutic target remains elusive.

METHODS AND RESULTS

Single-cell RNA sequencing analysis showed aberrant endothelial TJ expressions in the thoracic aortas of patients with TAAD. In a β-aminopropionitrile (BAPN)-induced TAAD mouse model, endothelial TJ function was disrupted in the thoracic aortas at an early stage (5 and 10 days) as observed by a vascular permeability assay, while the intercellular distribution of crucial TJ components was significantly decreased by en face staining. For the non-invasive detection of endothelial TJ function, two dextrans of molecular weights 4 and 70 kDa were conjugated with the magnetic resonance imaging (MRI) contrast agent Gd-DOTA to synthesize FITC-dextran-DOTA-Gd and rhodamine B-dextran-DOTA-Gd. MRI images showed that both probes accumulated in the thoracic aortas of the BAPN-fed mice. Particularly, the mice with increased accumulated signals from 5 to 10 days developed TAAD at 14 days, whereas the mice with similar signals between the two time points did not. Furthermore, the protease-activated receptor 2 inhibitor AT-1001, which seals TJs, alleviated the BAPN-induced impairment of endothelial TJ function and expression and subsequently reduced TAAD incidence. Notably, endothelial-targeted ZO-1 conditional knockout increased TAAD incidence. Mechanistically, vascular inflammation and edema were observed in the thoracic aortas of the BAPN-fed mice, whereas these phenomena were attenuated by AT-1001.

CONCLUSION

The disruption of endothelial TJ function is an early event prior to TAAD formation, herein serving as a potential indicator and a promising target for TAAD.

11S Proteasome Activator REGγ Promotes Aortic Dissection by Inhibiting RBM3 (RNA Binding Motif Protein 3) Pathway

BACKGROUND

Aortic dissection (AD) is a life-threatening cardiovascular disorder with high mortality and lacking underlying mechanisms or effective treatments. REGγ, the 11S proteasome activator known to promote the degradation of cellular proteins in a ubiquitin- and ATP-independent manner, emerges as a new regulator in the cardiovascular system.

METHODS

Using β-aminopropionitrile (BAPN)-subjected REGγ knockout AD mice and Ang II (angiotensin II)-treated REGγ deficiency vascular smooth muscle cells (VSMCs) to explore the effect of REGγ in AD progression.

RESULTS

REGγ was upregulated in mouse aorta of β-aminopropionitrile-induced AD model in vivo and Ang II-treated VSMCs in vitro. REGγ deficiency ameliorated AD progression in β-aminopropionitrile-induced mice by protecting against the switch in VSMCs from contractile to synthetic phenotype through suppressing RBM3 (RNA-binding motif protein 3) decay. Mechanically, REGγ interacted with and degraded the RNA-binding protein RBM3 directly, leading to decreased mRNA stability, lowered expression and transcriptional activity of transcription factor SRF (serum response factor), subsequently reduced transcription of VSMCs-specific contractile genes, α-SMA (alpha-smooth muscle actin) and SM22α (smooth muscle 22 alpha), caused the switch in VSMCs from contractile to synthetic phenotype and associated AD progression. Ablation of endogenous SRF or RBM3, or overexpressing exogenous RBM3 in VSMCs significantly blocked or reestablished the REGγ-dependent action on VSMCs phenotypic switch of Ang II stimulation in vitro. Furthermore, exogenously introducing RBM3 improved the switch in VSMCs from contractile to synthetic phenotype and associated AD features caused by REGγ in vivo.

CONCLUSIONS

Our results demonstrated that REGγ promoted the switch in VSMCs from contractile to synthetic phenotype and AD progression by inhibiting RBM3-SRF pathway, indicated that modulating REGγ-proteasome activity may be a potential therapeutic approach for AD-associated cardiovascular dysfunction.

Establishment of a meta-analysis based novel aortic dissection mouse model

Aortic dissection (AD) is a life-threatening disease and the detailed mechanism remains unclear. Thus, proper animal models are urgently required to better understand its pathogenesis. Our current study aims to establish a reliable, time and cost-effective mouse AD model. To conduct the meta-analysis, we searched PubMed for related studies up to 2021 and statistical analysis was conducted using Review Manager 5.4. For the animal experiment, 6-week-old male ApoE^-/- mice were given β-aminopropionitrile (BAPN) at a concentration of 1 g/L for 3 weeks before being infused with saline, 1000 ng/kg/min or 2500 ng/kg/min angiotensin II (AngII) via osmotic mini pumps for 2 or 4 weeks. To determine the presence of AD, we performed B-ultrasonography, hematoxylin and eosin (H&E) staining, and van Gieson staining. The result of the meta-analysis showed that the use of BAPN and more than 2000 ng/kg/min AngII can increase the rate of AD formation, whereas administrating Ang II for more than 28 days has no significant effect on the rate of AD formation when compared with the less than 14 days group. In the present study, mice treated with BAPN combined with 2500 ng/kg/min AngII for 2 weeks (12/20) had a significantly higher AD formation rate than mice treated with BAPN combined with 1000 ng/kg/min Ang II for 4 weeks (2/10), and had a similar model formation rate compared with the mice treated withβ-aminopropionitrile combined with 2500 ng/kg/min AngII for 4 weeks (6/10). There were 3 mice (3/10) and 6 mice (6/20) who died in the group treated with β-aminopropionitrile combined with 2500 ng/kg/min AngII for 4 weeks and 2 weeks respectively, and only one mouse (1/10) died in the group treated with β-aminopropionitrile combined with 1000 ng/kg/min AngII for 4 weeks. In 6-week-old male ApoE^-/- mice that received with 1 g/L BAPN in the drinking water for 3 weeks along with 2500 ng/kg/min AngII infusion via osmotic mini pumps for 2 weeks, the highest model formation rate and relative lower cumulative mortality were noted.

Acute aortic syndromes: An internist's guide to the galaxy

Acute aortic syndromes (AASs) are severe conditions defined by dissection, hemorrhage, ulceration or rupture of the thoracic aorta. AASs share etiological and pathophysiological features, including long-term aortic tissue degeneration and mechanisms of acute aortic damage. The clinical signs and symptoms of AASs are unspecific and heterogeneous, requiring large differential diagnosis. When evaluating a patient with AAS-compatible symptoms, physicians need to integrate clinical probability assessment, bedside imaging techniques such as point-of-care ultrasound, and blood test results such as d-dimer. The natural history of AASs is dominated by engagement of ischemic, coagulative and inflammatory pathways at large, causing multiorgan damage. Medical treatment, multiorgan monitoring and outcome prognostication are therefore paramount, with internal medicine playing a key role in non-surgical management of AASs.

The neutrophil: A key resourceful agent in immune‐mediated vasculitis

The term "vasculitis" refers to a group of rare immune-mediated diseases characterized by the dysregulated immune system attacking blood vessels located in any organ of the body, including the skin, lungs, and kidneys. Vasculitides are classified according to the size of the vessel that is affected. Although this observation is not specific to small-, medium-, or large-vessel vasculitides, patients show a high circulating neutrophil-to-lymphocyte ratio, suggesting the direct or indirect involvement of neutrophils in these diseases. As first responders to infection or inflammation, neutrophils release cytotoxic mediators, including reactive oxygen species, proteases, and neutrophil extracellular traps. If not controlled, this dangerous arsenal can injure the vascular system, which acts as the main transport route for neutrophils, thereby amplifying the initial inflammatory stimulus and the recruitment of immune cells. This review highlights the ability of neutrophils to "set the tone" for immune cells and other cells in the vessel wall. Considering both their long-established and newly described roles, we extend their functions far beyond their direct host-damaging potential. We also review the roles of neutrophils in various types of primary vasculitis, including immune complex vasculitis, anti-neutrophil cytoplasmic antibody-associated vasculitis, polyarteritis nodosa, Kawasaki disease, giant cell arteritis, Takayasu arteritis, and Behçet's disease.

Current Understanding of Aortic Dissection

The aorta is the largest artery in the body, delivering oxygenated blood from the left ventricle to all organs. Dissection of the aorta is a lethal condition caused by a tear in the intimal layer of the aorta, followed by blood loss within the aortic wall and separation of the layers to full dissection. The aorta can be affected by a wide range of causes including acute conditions such as trauma and mechanical damage; and genetic conditions such as arterial hypertension, dyslipidaemia, and connective tissue disorders; all increasing the risk of dissection. Both rapid diagnostic recognition and advanced multidisciplinary treatment are critical in managing aortic dissection patients. The treatment depends on the severity and location of the dissection. Open surgical repair is the gold standard of treatment for dissections located to the proximal part of the aorta and the arch, while endovascular interventions are recommended for most distal or type B aortic dissections. In this review article, we examine the epidemiology, pathophysiology, contemporary diagnoses, and management of aortic dissection.

Targeted Inhibition of Matrix Metalloproteinase-8 Prevents Aortic Dissection in a Murine Model

Aortic dissection (AD) is a lethal aortic pathology without effective medical treatments since the underlying pathological mechanisms responsible for AD remain elusive. Matrix metalloproteinase-8 (MMP8) has been previously identified as a key player in atherosclerosis and arterial remodeling. However, the functional role of MMP8 in AD remains largely unknown. Here, we report that an increased level of MMP8 was observed in 3-aminopropionitrile fumarate (BAPN)-induced murine AD. AD incidence and aortic elastin fragmentation were markedly reduced in MMP8-knockout mice. Importantly, pharmacologic inhibition of MMP8 significantly reduced the AD incidence and aortic elastin fragmentation. We observed less inflammatory cell accumulation, a lower level of aortic inflammation, and decreased smooth muscle cell (SMC) apoptosis in MMP8-knockout mice. In line with our previous observation that MMP8 cleaves Ang I to generate Ang II, BAPN-treated MMP8-knockout mice had increased levels of Ang I, but decreased levels of Ang II and lower blood pressure. Additionally, we observed a decreased expression level of vascular cell adhesion molecule-1 (VCAM1) and a reduced level of reactive oxygen species (ROS) in MMP8-knockout aortas. Mechanistically, our data show that the Ang II/VCAM1 signal axis is responsible for MMP8-mediated inflammatory cell invasion and transendothelial migration, while MMP8-mediated SMC inflammation and apoptosis are attributed to Ang II/ROS signaling. Finally, we observed higher levels of aortic and serum MMP8 in patients with AD. We therefore provide new insights into the molecular mechanisms underlying AD and identify MMP8 as a potential therapeutic target for this life-threatening aortic disease.

Emerging Role of Non-Coding RNAs in Aortic Dissection

Aortic dissection (AD) is a fatal cardiovascular acute disease with high incidence and mortality, and it seriously threatens patients’ lives and health. The pathogenesis of AD mainly includes vascular inflammation, extracellular matrix degradation, and phenotypic conversion as well as apoptosis of vascular smooth muscle cells (VSMCs); however, its detailed mechanisms are still not fully elucidated. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are an emerging class of RNA molecules without protein-coding ability, and they play crucial roles in the progression of many diseases, including AD. A growing number of studies have shown that the dysregulation of ncRNAs contributes to the occurrence and development of AD by modulating the expression of specific target genes or the activity of related proteins. In addition, some ncRNAs exhibit great potential as promising biomarkers and therapeutic targets in AD treatment. In this review, we systematically summarize the recent findings on the underlying mechanism of ncRNA involved in AD regulation and highlight their clinical application as biomarkers and therapeutic targets in AD treatment. The information reviewed here will be of great benefit to the development of ncRNA-based therapeutic strategies for AD patients.

C/EBPα-Mediated Transcriptional Activation of PIK3C2A Regulates Autophagy, Matrix Metalloproteinase Expression, and Phenotypic of Vascular Smooth Muscle Cells in Aortic Dissection

Purpose

To investigate the function of C/EBPα in the development of aortic dissection (AD) and the underlying mechanism.

Methods

Aortic vascular smooth muscle cells (VSMCs) were isolated, cultured, and identified from AD rats. Then, C/EBPα and PIK3C2A were knockdown or overexpressed by siRNA or plasmid transfection, respectively. Rapamycin or 3-MA was utilized to stimulate and restrain autophagy of VSMCs, respectively. Western blot was used to evaluate the expression levels of C/EBPα, PIK3C2A, LC3, Beclin-1, p62, MMP-2, MMP-9, α-SMA, SM-MHC, and OPN. The pathological status of aortic ring was evaluated by stretch stress, and ChIP assay was used to analyze the binding between C/EBPα and PIK3C2A. C/EBPα shRNA was injected into tail vein to observe the effect of C/EBPα knockdown in vivo on phenotype, autophagy of aortic vascular tissue by immunohistochemical staining and Western blot.

Results

The protein levels of C/EBPα, PIK3C2A, MMP-2, MMP-9, and LC3 in the aorta of AD rats were all upregulated significantly. C/EBPα and rapamycin promoted notable upregulation of the synthesized proteins (OPN), PIK3C2A, matrix metalloproteinases, LC3, and Beclin-1 in VSMCs, while suppressed contractile proteins (α-SMA and SM-MHC) and p62. The opposite results were observed in the C/EBPα-knockdown VSMCs, PIK3C2A-knockdown VSMCs, or VSMCs treated with 3-MA. C/EBPα, PIK3C2A, and LC3 were dramatically upregulated by the stimulation of 3 g and 5 g stretch stress. The downregulated contractile proteins, upregulated synthetic proteins, activated autophagy, and aggravated pathological state in 5 g stretch stress-treated aortic rings were significantly reversed by the knockdown of C/EBPα. ChIP results indicated that there was a binding site for C/EBPα in the promoter of PIK3C2A. C/EBPα also downregulated α-SMA level and upregulated OPN levels in AD rats in vivo.

Conclusion

Our data indicated that during the development of AD, C/EBPα regulated the transition of VSMC phenotype and extracellular matrix remodeling by activating autophagy through regulating the transcriptional activity of PIK3C2A promoter.

A Body Shape Index and Aortic Disease-Related Mortality in Japanese General Population

AIMS

Aortic diseases (ADs), including aortic dissection, aortic aneurysm, and aortic rupture, are fatal, with extremely high mortality rates. A body shape index (ABSI), an anthropometric measure calculated as waist circumference adjusted by height and weight, improves the predictive capacity for mortality. However, whether ABSI is a risk factor for AD-related mortality in the general population remains unclear.

METHODS

We used a nationwide database of 630,842 individuals (aged 40-75 years) who participated in the annual "Specific Health Check and Guidance in Japan" between 2008 and 2010.

RESULTS

During the follow-up period of 3.8 years, 159 AD-related deaths occurred, including 105 aortic dissections and 54 aortic aneurysm ruptures. The subjects were divided into three groups based on ABSI tertiles. Kaplan-Meier analysis demonstrated that the 3^rd tertile (with the highest ABSI) had the greatest risk among the three groups. Multivariate Cox proportional hazard regression analysis demonstrated that ABSI was significantly associated with AD-related death after adjusting for confounding risk factors. Neither waist circumference nor body mass index consistently predicted AD-related death in the multivariate model. The prediction capacity was significantly improved by the addition of ABSI to the confounding risk factors.

CONCLUSIONS

We demonstrated for the first time that ABSI, a surrogate marker for abdominal visceral fat tissue, was associated with AD-related deaths in the general population, suggesting the importance of central adiposity in the development of AD.

Methamphetamine induces thoracic aortic aneurysm/dissection through C/EBPβ

AIMS

Thoracic aortic aneurysm/dissection (TAAD) is a life-threatening disease with diverse clinical manifestations. Although the association between methamphetamine (METH) and TAAD is frequently observed, the causal relationship between METH abuse and aortic aneurysm/dissection has not been established. This study was designed to determine if METH causes aortic aneurysm/dissection and delineate the underlying mechanism.

METHODS AND RESULTS

A new TAAD model was developed by exposing METH to SD rats pre-treated with lysyl oxidase inhibitor β-aminopropionitrile (BAPN). Combination of METH and BAPN caused thoracic aortic aneurysm/dissection in 60% of rats. BAPN+METH significantly increased the expression and activities of both matrix metalloproteinase MMP2 and MMP9, consistent with the severe elastin breakage and dissection. Mechanistically, METH increased CCAAT-enhancer binding protein β (C/EBPβ) expression by enhancing mothers against decapentaplegic homolog 3 (Smad3) and extracellular regulated protein kinase (ERK1/2) signaling. METH also promoted C/EBPβ binding to MMP2 and MMP9 promoters. Blocking C/EBPβ significantly attenuated METH+BAPN-induced TAAD and MMP2/MMP9 expression. Moreover, BAPN+METH promoted aortic medial smooth muscle cell (SMC) apoptosis through C/EBPβ-mediated IGFBP5/p53/PUMA signaling pathways. More importantly, the expression of C/EBPβ, MMP2/MMP9, and apoptosis-promoting proteins was increased in the aorta of human patients with thoracic aortic dissection, suggesting that the mechanisms identified in animal study could be relevant to human disease.

CONCLUSIONS

Our study demonstrated that METH exposure has a casual effect on TAAD. C/EBPβ mediates METH-introduced TAAD formation by causing elastin breakage, medial cell loss and degeneration. Therefore, C/EBPβ may be a potential factor for TAAD clinical diagnosis or treatment.

Activation of AMP-activated protein kinase ablated the formation of aortic dissection by suppressing vascular inflammation and phenotypic switching of vascular smooth muscle cells

BACKGROUND

Aortic dissection (AD) is a fatal vascular disease in absence of effective pharmaceutical therapy. Adenosine monophosphate-activated protein kinase α (AMPKα) plays a critical role in various cardiovascular diseases. Whether AMPKα is involved in the pathogenesis of aortic dissection remains unknown. We aimed to determine whether activation of AMPKα prevents the formation of AD.

METHODS AND RESULTS

Reduced expression of phosphorylated AMPKα (Thr172) and exacerbated phenotypic switching were observed in human aortic tissues from aortic dissection patients compared with those in tissues from controls. In vivo, the formation of aortic dissection in ApoE^-/- mice was successfully induced by continuous infusion of angiotensin II (AngII) for two weeks, characterized by the activation of vascular inflammation, infiltration of macrophages and phenotypic switching of vascular smooth muscle cells (VSMCs). rAAV2-mediated overexpression of constitutively active AMPKα (CA-AMPKα) enhanced the expression of phosphorylated AMPKα (Thr172) and attenuated AngII-induced occurrence of aortic dissection by suppressing the infiltration of macrophages, activation of vascular inflammation and phenotypic switching of VSMCs. The pathogenesis above was conversely exacerbated by rAAV2-mediated overexpression of dominant negative AMPKα2 (DN-AMPKα). In vitro, we demonstrated that the administration of an AMPK agonist (AICAR) or transfection of CA-AMPKα induced the activation of AMPKα and then ameliorated AngII-induced phenotypic switching in the VSMCs and inflammation in the bone marrow-derived macrophages (BMDMs). This could be reversed by the addition of AMPK inhibitor compound C or transfection of DN-AMPKα.

CONCLUSION

Impaired activation of AMPKα may increase the susceptibility to aortic dissection. Our findings verified the protective effects of AMPKα on the formation of aortic dissection and may provide evidence for clinical prevention or treatment.

Progress in murine models of ruptured abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a focal dilation of the aorta that is prevalent in aged populations. The progressive and unpredictable expansion of AAA could result in aneurysmal rupture, which is associated with ~80% mortality. Due to the expanded screening efforts and progress in diagnostic tools, an ever-increasing amount of asymptomatic AAA patients are being identified yet without a cure to stop the rampant aortic expansion. A key barrier that hinders the development of effective AAA treatment is our incomplete understanding of the cellular and molecular basis of its pathogenesis and progression into rupture. Animal models provide invaluable mechanistic insights into AAA pathophysiology. However, there is no single experimental model that completely recapitulate the complex biology behind AAA, and different AAA-inducing methodologies are associated with distinct disease course and rupture rate. In this review article, we summarize the established murine models of ruptured AAA and discuss their respective strengths and utilities.

The role of neutrophils in the dysfunction of central nervous system barriers

Leukocyte migration into the central nervous system (CNS) represents a central process in the development of neurological diseases with a detrimental inflammatory component. Infiltrating neutrophils have been detected inside the brain of patients with several neuroinflammatory disorders, including stroke, multiple sclerosis and Alzheimer’s disease. During inflammatory responses, these highly reactive innate immune cells can rapidly extravasate and release a plethora of pro-inflammatory and cytotoxic factors, potentially inducing significant collateral tissue damage. Indeed, several studies have shown that neutrophils promote blood-brain barrier damage and increased vascular permeability during neuroinflammatory diseases. Recent studies have shown that neutrophils migrate into the meninges and choroid plexus, suggesting these cells can also damage the blood-cerebrospinal fluid barrier (BCSFB). In this review, we discuss the emerging role of neutrophils in the dysfunction of brain barriers across different neuroinflammatory conditions and describe the molecular basis and cellular interplays involved in neutrophil-mediated injury of the CNS borders.

Iron deficiency promotes aortic media degeneration by activating endoplasmic reticulum stress-mediated IRE1 signaling pathway

BACKGROUND

Aortic dissection (AD) is a macrovascular disease which is pathologically characterized by aortic media degeneration (AMD). Our team's previous research found that iron deficiency (ID) promoted the formation of AMD through presentative research. In this study, we aimed to investigate the underlying mechanism of ID promoting AMD formation.

METHODS

The human aortic tissues were harvested from AD patients and organ donors. ApoE-/- mice were simultaneously given AngII infusion and low-iron feed to investigate the relationship between ID and AD. The IRE1-XBP1-CHOP signal axis of endoplasmic reticulum (ER) stress was selectively inhibited with 4μ8C. Iron contents were detected by Perls staining. The expression of iron metabolism and ER stress-relative proteins were analyzed by IF and western blotting. Apoptosis rates of aortic tissue and ASMCs were detected by TUNEL staining and flow cytometry, and ROS content was also measured by the flow cytometry.

RESULTS

ID was accompanied by ER stress in patients with AD. Among the three signaling pathways of ER stress in ID-induced AMD, proteins of IRE1, PERK and ATF6 signaling pathways were up-regulated by 2.65 times, 1.14 times and 1.24 times, respectively. ID was positively related to ER stress, mitochondrial oxidative stress and aortic media apoptosis in vivo and in vitro assays, while 4μ8C reversed the severity of ER stress and AMD.

CONCLUSIONS

ID could activate ER stress by eliciting mitochondrial oxidative stress to activate the IRE1-XBP1-CHOP signaling pathway in the ER, which accelerated the apoptosis of ASMCs in aortic media, thus promoting the formation of AMD.

High Neutrophil-to-Platelet Ratio Is Associated with Poor Survival in Patients with Acute Aortic Dissection

BACKGROUND

Acute aortic dissection (AAD), a serious and fatal cardiovascular disease, is characterized by inflammation that may further aggravate the condition. We evaluated the value of the neutrophil-to-platelet ratio (NPR) in the prognosis of AAD.

METHODS

We collected records of patients with AAD and clinical data from 2010 to 2020 and followed up on the relevant information for 136 months. The Kaplan-Meier (K-M) survival along with the univariate and multivariate Cox analyses was used to examine the prognostic value of NPR in AAD. In addition, nomograms were constructed by combining NPR, age, Stanford typing, and treatment methods. The accuracy of nomograms was evaluated using calibration plots, and the prediction efficiency of nomograms was evaluated by receiver operating characteristic curve analysis and decision curve analysis (DCA).

RESULTS

The K-M analysis showed that AAD patients with higher NPR exhibited worse prognosis. In addition, different Stanford typing and treatment methods produced varied prognosis results. Univariate and multivariate Cox analyses showed that NPR value, age, classification, and treatment were independent prognostic factors for the overall survival time of patients with AAD. Nomograms constructed by combining NPR, age, Stanford typing, and treatment methods showed good predictive efficacy, and the AUC values for 1-, 3-, and 5-year predicting were 0.82, 0.79, and 0.74, respectively.

CONCLUSIONS

Our results suggest that pretreatment NPR can be used as a potential prognostic marker of overall survival time in patients with AAD.

Syndecan-1 Is Overexpressed in Human Thoracic Aneurysm but Is Dispensable for the Disease Progression in a Mouse Model

Glycosaminoglycans (GAGs) pooling has long been considered as one of the histopathological characteristics defining thoracic aortic aneurysm (TAA) together with smooth muscle cells (SMCs) apoptosis and elastin fibers degradation. However, little information is known about GAGs composition or their potential implication in TAA pathology. Syndecan-1 (SDC-1) is a heparan sulfate proteoglycan that is implicated in extracellular matrix (ECM) interaction and assembly, regulation of SMCs phenotype, and various aspects of inflammation in the vascular wall. Therefore, the aim of this study was to determine whether SDC-1 expression was regulated in human TAA and to analyze its role in a mouse model of this disease. In the current work, the regulation of SDC-1 was examined in human biopsies by RT-qPCR, ELISA, and immunohistochemistry. In addition, the role of SDC-1 was evaluated in descending TAA in vivo using a mouse model combining both aortic wall weakening and hypertension. Our results showed that both SDC-1 mRNA and protein are overexpressed in the media layer of human TAA specimens. RT-qPCR experiments revealed a 3.6-fold overexpression of SDC-1 mRNA (p = 0.0024) and ELISA assays showed that SDC-1 protein was increased 2.3 times in TAA samples compared with healthy counterparts (221 ± 24 vs. 96 ± 33 pg/mg of tissue, respectively, p = 0.0012). Immunofluorescence imaging provided evidence that SMCs are the major cell type expressing SDC-1 in TAA media. Similarly, in the mouse model used, SDC-1 expression was increased in TAA specimens compared to healthy samples. Although its protective role against abdominal aneurysm has been reported, we observed that SDC-1 was dispensable for TAA prevalence or rupture. In addition, SDC-1 deficiency did not alter the extent of aortic wall dilatation, elastin degradation, collagen deposition, or leukocyte recruitment in our TAA model. These findings suggest that SDC-1 could be a biomarker revealing TAA pathology. Future investigations could uncover the underlying mechanisms leading to regulation of SDC-1 expression in TAA.

Dexamethasone attenuated thoracic aortic aneurysm and dissection in vascular smooth muscle cell Tgfbr2 disrupted mice with CCL8 suppression

NEW FINDINGS

What is the central question of this study? The aim of this study was to investigate the relationship of CCL8 and the thoracic aortic aneurysm and dissection (TAAD) formation in postnatal mice with vascular smooth muscle cell (VSMC) Tgfbr2 disruption and whether dexamethasone could be a potential treatment. What is the main finding and its importance? CCL8 was associated with the formation of TAAD in VSMC Tgfbr2 disrupted mice. Dexamethasone reduced TAAD formation and inhibited MAPK (p-p38) and NF-κB (p-p65) signaling pathways. CCL8 might be an important promoter in aortic inflammation. DEX provided potential therapeutic effects in TAAD treatment.

ABSTRACT

Aortic inflammation plays a vital role in initiation and progression of thoracic aortic aneurysm and dissection (TAAD). The disturbance of transforming growth factor-β (TGF-β) signaling pathway is believed to be one of the pathogenic mechanisms of TAAD. Initially, Myh11-CreER^T2 .Tgfbr2^f/f male mice were used to build TAAD mice model. And bioinformatics analyses revealed the enriched inflammatory signal pathways and upregulated chemokine CCL8. So we hypothesized that vascular smooth muscle cell (VSMC) Tgfbr2 disruption in postnatal mice resulted in aortic inflammation associated with CCL8 secretion. Then real-time quantitative PCR and serum ELISA results confirmed that CCL8 expression began to increase after VSMC Tgfbr2 disruption. Next, we cultured mouse thoracic aortas ex vivo, and observed that the protein expressions of CCL8 in culture supernatants were increased by ELISA. Subsequently, the co-localization of CCL8 with α-smooth muscle actin (α-SMA) orCD68 was found significantly increased by immunofluorescence. Then, dexamethasone (DEX) was used to treat TAAD in VSMC Tgfbr2 disrupted mice The results of histochemical, immunofluorescence and immunohistochemical staining indicated that DEX therapy reduced CCL8 secretion, inflammatory cell recruitment, aortic medial thickening, elastic fiber fragmentating, extracellular matrix degradation, contractile apparatus impairment, thereby ameliorated TAAD formation. Western blot showed that MAPK and NF-κB signaling pathways in aorta were overactivated after VSMC Tgfbr2 disruption, but inhibited by DEX therapy. Altogether, CCL8 might be an important promoter in TAAD formation of VSMC Tgfbr2 disrupted mice. And DEX provided potential therapeutic effects in TAAD treatment. This article is protected by copyright. All rights reserved.

CD11b-Based Pre-Targeted SPECT/CT Imaging Allows for the Detection of Inflammation in Aortic Aneurysm

Purpose

To investigate the feasibility of a pre-targeted imaging strategy based on the cycloaddition between 1,2,4,5-terazine (Tz) and trans-cyclooctene (TCO) for evaluating CD11b expression in inflammatory aortic aneurysm (AA) using single photon emission computed tomography/computed tomography (SPECT/CT).

Methods

C57BL/6J mice were fed β-aminopropionitrile (1 g/kg/day) for 4 weeks to establish AA models. Anti-CD11b-TCO was synthesized and ^99mTc-HYNIC-PEG₁₁-Tz was designed for pre-targeted SPECT/CT. The affinity and specificity of the probe for the inflammatory cell line Raw-264.7 were investigated. Then, anti-CD11b-TCO pre-targeted and ^99mTc-HYNIC-PEG₁₁-Tz based SPECT/CT were performed to detect in vivo inflammation in AA. Finally, ex vivo aortic breast-specific gamma imaging (BSGI), Western blot assays, and immunohistochemical CD11b staining were performed to confirm the in vivo findings of SPECT/CT.

Results

In the AA models, 65.22% (15/23) had aortic lesions, including 43.48% (10/23) AA lesions. The anti-CD11b-TCO presented with a high TCO coupling ratio (7.43), and the ^99mTc-HYNIC-PEG₁₁-Tz showed high radio-purity (>95%), good in vitro stability and a rapid clearance rate. Additionally, anti-CD11b-TCO and ^99mTc-HYNIC-PEG₁₁-Tz presented high click rate (~89%). The in vitro clicked compound, ^99mTc-HYNIC-PEG₁₁-Tz/TCO-anti-CD11b, showed high affinity and specificity for Raw-264.7 cells. ^99mTc-HYNIC-PEG₁₁-Tz/TCO-anti-CD11b pre-targeting SPECT/CT successfully demonstrated inflammatory AA with a high AA-to-background ratio in AA mice, compared to AA mice that were injected with ^99mTc-HYNIC-Tz/TCO-IgG (8.13 versus 3.71, P < 0.001) and control mice injected with ^99mTc-HYNIC-Tz/TCO-anti-CD11b (8.13 versus 3.66, P < 0.001). This result was confirmed by ex vivo BSGI performed immediately after SPECT/CT and immunohistochemical CD11b staining.

Conclusion

SPECT/CT imaging using the anti-CD11b-TCO/Tz-PEG₁₁-HYNIC-^99mTc based pre-targeting imaging strategy allows for the detection of inflammation in progressive AA.

Peripheral Neutrophils-Derived Matrix Metallopeptidase-9 Induces Postoperative Cognitive Dysfunction in Aged Mice

Background

Aging is one of the most important risk factors of postoperative cognitive dysfunction (POCD); however, the mechanisms are still not completely understood. In this study, we explore the roles of matrix metalloproteinase-9 (MMP-9) in aged mice with POCD.

Methods

Appendectomy was performed in 18-month-old C57BL/6 and MMP-9^–/– mice under anesthesia to establish the POCD model. Learning and memory were assessed using the Morris water maze (MWM) or Barnes maze. Protein expression of MMP-9 was measured by Western blotting or enzyme-linked immunosorbent assay (ELISA). To explore the role of neutrophils-derived MMP-9 in POCD, we treated mice with anti-Gr-1 monoclonal antibody to deplete peripheral neutrophils. And the percentage of neutrophils and other leukocytes were detected by flow cytometry. We further used sodium fluorescein (NaFlu) to evaluate the blood–brain barrier (BBB) permeability.

Results

The spatial learning and memory ability was injured, and expression of MMP-9 increased in both plasma and the hippocampus after anesthesia/surgery. However, cognitive dysfunction was alleviated in both MMP-9^–/– and peripheral neutrophils-depleted mice. The permeability of BBB was increased after anesthesia/surgery while recused by anti-Gr-1 antibody administration.

Conclusion

These findings suggest that peripheral neutrophils-derived MMP-9 could lead to POCD of aged mice through increasing the BBB permeability.

Imaging Techniques for Aortic Aneurysms and Dissections in Mice: Comparisons of Ex Vivo, In Situ, and Ultrasound Approaches

Aortic aneurysms and dissections are life-threatening conditions that have a high risk for lethal bleeding and organ malperfusion. Many studies have investigated the molecular basis of these diseases using mouse models. In mice, ex vivo, in situ, and ultrasound imaging are major approaches to evaluate aortic diameters, a common parameter to determine the severity of aortic aneurysms. However, accurate evaluations of aortic dimensions by these imaging approaches could be challenging due to pathological features of aortic aneurysms. Currently, there is no standardized mode to assess aortic dissections in mice. It is important to understand the characteristics of each approach for reliable evaluation of aortic dilatations. In this review, we summarize imaging techniques used for aortic visualization in recent mouse studies and discuss their pros and cons. We also provide suggestions to facilitate the visualization of mouse aortas.

Diagnostic and Prognostic Value of Neutrophil Extracellular Trap Levels in Patients With Acute Aortic Dissection

Background

Acute aortic dissection (AAD) is a fatal disease demanding prompt diagnosis and proper treatment. There is a lack of serum markers that can effectively assist diagnosis and predict prognosis of AAD patients.

Methods

Ninety-six AAD patients were enrolled in this study, and 249 patients with chest pain due to acute myocardial infarction, pulmonary embolism, intramural hematoma, angina or other causes and 80 healthy controls were included as control group and healthy control group. Demographics, biochemical and hematological data and risk factors were recorded as baseline characteristics. The 1-year follow-up data were collected and analyzed. The diagnostic performance and ability to predict disease severity and prognosis of NET components in serum and aortic tissue were evaluated.

Results

Circulating NET markers, citH3 (citrullination of histone 3), cell-free DNA (cfDNA) and nucleosomes, had good diagnostic value for AAD, with superior diagnostic performance to D-dimer in discriminating patients with chest pain due to other reasons in the emergency department. Circulating NET marker levels (i.e., citH3, cfDNA and nucleosomes) of AAD patients were significantly higher than that of control group and healthy control group. In addition, circulating NET markers levels were closely associated with the disease severity, in-hospital death and 1-year survival of AAD patients. Systolic blood pressure < 90 mmHg and serum citH3 levels were identified as independent risk factors for 1-year survival of AAD patients. Excessive NET components (i.e., neutrophil elastase and citH3) in the aortic tissue of AAD patient were significantly higher than that of healthy donor aortic tissue. The expression levels of granules and nuclear NET components were significantly higher in aortic tissue from AAD patients than controls.

Conclusions

Circulating NET markers, citH3, cfDNA and nucleosomes, have significant diagnostic value and predictive value of disease severity and prognosis of AAD patients. The NETs components may constitute a useful diagnostic and prognostic marker in AAD patients.

Crucial Genes in Aortic Dissection Identified by Weighted Gene Coexpression Network Analysis

Background

Aortic dissection (AD) is a lethal vascular disease with high mortality and morbidity. Though AD clinical pathology is well understood, its molecular mechanisms remain unclear. Specifically, gene expression profiling helps illustrate the potential mechanism of aortic dissection in terms of gene regulation and its modification by risk factors. This study was aimed at identifying the genes and molecular mechanisms in aortic dissection through bioinformatics analysis.

Method

Nine patients with AD and 10 healthy controls were enrolled. The gene expression in peripheral mononuclear cells was profiled through next-generation RNA sequencing. Analyses including differential expressed gene (DEG) via DEGseq, weighted gene coexpression network (WGCNA), and VisANT were performed to identify crucial genes associated with AD. The Database for Annotation, Visualization, and Integrated Discovery (DAVID) was also utilized to analyze Gene Ontology (GO).

Results

DEG analysis revealed that 1,113 genes were associated with AD. Of these, 812 genes were markedly reduced, whereas 301 genes were highly expressed, in AD patients. DEGs were rich in certain categories such as MHC class II receptor activity, MHC class II protein complex, and immune response genes. Gene coexpression networks via WGCNA identified 3 gene hub modules, with one positively and 2 negatively correlated with AD, respectively. Specifically, module 37 was the most strongly positively correlated with AD with a correlation coefficient of 0.72. Within module 37, five hub genes (AGFG1, MCEMP1, IRAK3, KCNE1, and CLEC4D) displayed high connectivity and may have clinical significance in the pathogenesis of AD.

Conclusion

Our analysis provides the possible association of specific genes and gene modules for the involvement of the immune system in aortic dissection. AGFG1, MCEMP1, IRAK3, KCNE1, and CLEC4D in module M37 were highly connected and strongly linked with AD, suggesting that these genes may help understand the pathogenesis of aortic dissection.

Insulin Resistance Promotes the Formation of Aortic Dissection by Inducing the Phenotypic Switch of Vascular Smooth Muscle Cells

Background

Insulin resistance (IR) plays a key role in the development of type 2 diabetes mellitus (T2DM) and is one of its most important characteristics. Previous studies have shown that IR and T2DM were independent risk factors for a variety of cardiovascular and cerebrovascular diseases. However, there are few studies on the relationship between IR and aortic dissection (AD). The goal of this research was to find evidence that IR promotes the occurrence of AD.

Methods

Through the statistical analysis, we determined the proportion of glycosylated hemoglobin (HbA1c) abnormalities (HbA1c > 5.7) in people with acute thoracic aortic dissection (ATAD) and compared the difference of messenger RNA (mRNA) and protein expression of GluT1 in the thoracic aorta of normal people and those with ATAD to find evidence that IR is a causative factor in AD. The mouse model of IR and AD and the IR model of human aortic vascular smooth muscle cells (HA-VSMC) were established. Real time-PCR (RT-PCR) and Western blotting were used to study the mRNA and protein expression. Hematoxylin and eosin (H&E), Masson, and elastic fiber staining, and immunofluorescence were used to study the morphological structure.

Results

The proportion of HbA1c abnormalities in patients with ATAD was 59.37%, and the mRNA and protein expression of GluT1 were significantly lower than that in normal people. Fasting glucose concentration (FGC), serum insulin concentration (SIC), and the homeostasis model assessment of insulin resistance (HOMA-IR) of mice was obviously increased in the high-fat diet group and the protein expressions of Glut1 and GluT4 were reduced, indicating that the mouse IR model was successfully established. The incidence of AD was different between the two groups (IR: 13/14, Ctrl: 6/14), and the protein expression of MMP2, MMP9, and OPN were upregulated and SM22 and α-SMA were downregulated in mice. The expressions of mRNA and protein of GluT1 and SM22 in HA-VSMCs with IR were reduced and OPN was increased.

Conclusion

Combined results of clinical findings, mouse models, and cell experiments show that IR induced the phenotypic switching of vascular smooth muscle cells (VSMCs) from contractile to synthetic, which contributes to the occurrence of AD. It provides a basis for further research on the specific mechanism of how IR results in AD and a new approach for the prevention and treatment of AD.