STAT3 Activation Correlates with Adventitial Neutrophil Infiltration in Human Aortic Dissection

From inflammation to remodelling: A novel BASP1+ monocyte subset as a catalyst for acute aortic dissection

INTRODUCTION

Monocytes comprise heterogeneous cell populations. However, beyond traditionally considered as precursors of tissue macrophages, heterogeneity and detailed effects of monocytes in acute aortic dissection (AAD) are largely unknown.

OBJECTIVES

To investigate the role of brain soluble acid protein 1 positive (BASP1+) monocyte subset in promoting AAD development as well as the underlying mechanism.

METHODS

Monocyte/macrophage heterogeneity in both human peripheral blood and aortic tissues were assayed by scRNA-seq. Monocyte trafficking and lineage tracing were detected by immunofluorescence and using BASP1-CreER/Lyz2-DreER-tdT reporter mice with AAD. The effects and underlying mechanism were investigated by laser speckle image, ultrasound imaging, Co-IP, ChIP-sequencing. Conditional knockout of BASP1 on monocyte and BASP1 siRNA were used to observe BASP1+ monocyte subset-targeted AAD intervention.

RESULTS

"PIP2-SP1-ACTN1/VAV3" and "ITGB1-Rac1-GSN" signalling mediated BASP1+ monocyte subset as the first line immune cells infiltrating aortic tissues in AAD induction and partial of them transformed to BASP1+ macrophages to amplify the inflammation. Meanwhile, BASP1+ monocyte subset induced an inflammatory phenotype vascular smooth muscle cell (VSMC) subset and a ROS-enriched endothelial cell (EC) subset accompanied with promoting the apoptosis of normal VSMC and EC, contributing to vascular remodelling and dampening the myo-endothelial gap junction. Selective deletion of BASP1+ monocyte subset and interference with BASP1 expression in monocytes both inhibited the development of AAD in mice.

CONCLUSION

Interpretation BASP1+ monocyte subset and its regulatory network provides deep insight into AAD pathogenesis and a novel potential target for early intervention in AAD formation.

Preoperative clinical characteristics and risk assessment in Sun's modified classification of Stanford type A acute aortic dissection

OBJECTIVES

This study aims to retrospectively analyze the clinical features of Stanford type A acute aortic dissection (TAAAD) based on Sun's modified classification, and to investigate whether the Sun's modified classification can be used to assess the risk of preoperative rupture.

METHODS

Clinical data was collected between January 2018 and June 2019. Data included patient demographics, history of disease, type of dissection according to the Sun's modified classification, time of onset, biochemical tests, and preoperative rupture.

RESULTS

A total of 387 patients with TAAAD who met the inclusion criteria of Sun's modified classification were included. There were more complex types, with 75, 151 and 140 patients in the type A1C, A2C and A3C groups, respectively. The age of the entire group of patients was 51.46 ± 12.65 years and 283 (73.1%) were male. The time from onset to the emergency room was 25.37 ± 30.78 h. There were a few cases of TAAAD combined with stroke, pericardial effusion, pleural effusion, and lower extremity and organ ischemia in the complex type group. The white blood cell count (WBC), neutrophil count (NEC) and blood amylase differed significantly between the groups. Three independent risk factors for preoperative rupture were identified: neutrophil count, blood potassium ion level, and platelet count. Binary logistic regression analysis showed that the Sun's modified classification could not be used to assess the risk of preoperative rupture in TAAAD.

CONCLUSION

TAAAD was classified as the complex type in most patients. WBC, NEC and blood amylase were significantly different between the groups. NEC and serum potassium ion level were independent risk factors for preoperative rupture of TAAAD, while platelet count was its protective factor. More samples are needed to determine whether Sun's modified classification can be used to evaluate the risk of preoperative rupture.

Roles of pyroptosis and immune infiltration in aortic dissection

Introduction: Aortic dissection (AD) is often fatal, and its pathogenesis involves immune infiltration and pyroptosis, though the molecular pathways connecting these processes remain unclear. This study aimed to investigate the role of immune infiltration and pyroptosis in AD pathogenesis using bioinformatics analysis. Methods: Two Gene Expression Omnibus datasets and a Gene Cards dataset of pyroptosis-related genes (PRGs) were utilized. Immunological infiltration was assessed using CIBERSORT, and AD diagnostic markers were identified through univariate logistic regression and least absolute shrinkage and selection operator regression. Interaction networks were constructed using STRING, and weighted gene correlation network analysis (WGCNA) was employed to identify important modules and essential genes. Single-sample gene set enrichment analysis determined immune infiltration, and Pearson correlation analysis assessed the association of key genes with infiltrating immune cells. Results: Thirty-one PRGs associated with inflammatory response, vascular epidermal growth factor receptor, and Rap1 signaling pathways were identified. WGCNA revealed seven important genes within a critical module. CIBERSORT detected immune cell infiltration, indicating significant changes in immune cell infiltration and pyroptosis genes in AD and their connections. Discussion: Our findings suggest that key PRGs may serve as indicators for AD or high-risk individuals. Understanding the role of pyroptosis and immune cell infiltration in AD pathogenesis may lead to the development of novel molecular-targeted therapies for AD. Conclusion: This study provides insights into the molecular mechanisms underlying AD pathogenesis, highlighting the importance of immune infiltration and pyroptosis. Identification of diagnostic markers and potential therapeutic targets may improve the management of AD and reduce associated morbidity and mortality.

Gut Microbiota-Derived Tryptophan Metabolite Indole-3-aldehyde Ameliorates Aortic Dissection

Tryptophan, an essential dietary amino acid, is metabolized into various metabolites within both gut microbiota and tissue cells. These metabolites have demonstrated potential associations with panvascular diseases. However, the specific relationship between tryptophan metabolism, particularly Indole-3-aldehyde (3-IAId), and the occurrence of aortic dissection (AD) remains unclear. 3-IAId showed an inverse association with advanced atherosclerosis, a risk factor for AD. In this study, we employed a well-established β-aminopropionitrile monofumarate (BAPN)-induced AD murine model to investigate the impact of 3-IAId treatment on the progression of AD. Our results reveal compelling evidence that the administration of 3-IAId significantly mitigated aortic dissection and rupture rates (BAPN + 3-IAId vs. BAPN, 45% vs. 90%) and led to a notable reduction in mortality rates (BAPN + 3-IAId vs. BAPN, 20% vs. 55%). Furthermore, our study elucidates that 3-IAId exerts its beneficial effects by inhibiting the phenotype transition of vascular smooth muscle cells (VSMCs) from a contractile to a synthetic state. It also mitigates extracellular matrix degradation, attenuates macrophage infiltration, and suppresses the expression of inflammatory cytokines, collectively contributing to the attenuation of AD development. Our findings underscore the potential of 3-IAId as a promising intervention strategy for the prevention of thoracic aortic dissection, thus providing valuable insights into the realm of vascular disease management.

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.

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.

Interferon signature in giant cell arteritis aortitis

OBJECTIVES

Molecular mechanisms underlying large-vessel involvement in giant cell arteritis (LV-GCA) are largely unknown. Herein, we explore the critical involvement of pro-inflammatory signaling pathways in both aorta and T cells from patients with LV-GCA.

METHODS

We analyzed transcriptome and interferon gene signature in inflamed aortas from LV-GCA patients and compared them to non-inflammatory control aorta. Differential transcriptomic analyses of circulating CD4⁺ and CD8⁺ T cells were also performed between patients with active GCA (not under any immunosuppressants or corticosteroid doses higher than 10 mg/day by the time of blood collection) and healthy donors. Interferon-alpha serum levels were measured using ultra-sensitive technique (HD-X Simoa Planar Technology) in GCA patients according to disease activity status.

RESULTS

Transcriptomic analyses revealed 1042, 1479 and 2075 significantly dysregulated genes for aortas, CD4⁺ and CD8⁺ cells from LV-GCA patients, respectively, as compared to controls. A great enrichment for pathways linked to interferons (type I, II and III), JAK/STAT signaling, cytokines and chemokines was seen across aortas and circulating T cells. A type I interferon signature was identified as significantly upregulated in the aorta of patients with LV-GCA, notably regarding EPSTI1 and IFI44L genes. STAT3 was significantly upregulated in both aorta and T cells and appeared as central in related gene networks from LV-GCA patients. Interferon-alpha serum levels were higher in patients with active GCA when compared to those in remission (0.024 vs. 0.011 pg/mL; p = 0.028).

CONCLUSION

LV-GCA presents a clear type I interferon signature in aortas, which paves the way for tailored therapeutical targeting.

Analysis of Hub Genes and the Mechanism of Immune Infiltration in Stanford Type a Aortic Dissection

Background: Stanford type A aortic dissection (AAD) is a catastrophic disease. An immune infiltrate has been found within the aortic wall of dissected aortic specimens. The recall and activation of macrophages are key events in the early phases of AAD. Herein, the immune filtration profile of AAD was uncovered.

Methods: Gene expression data from the GSE52093, GSE98770 and GSE153434 datasets were downloaded from the Gene Expression Omnibus (GEO). The differentially expressed genes (DEGs) of each dataset were calculated and then integrated. A protein-protein interaction (PPI) network was established with the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING), and the hub genes were identified in Cytoscape. Furthermore, gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of hub genes were performed. Finally, we set GSE52093 and GSE98770 as the training set and GSE153434 as the validation set to assess immune infiltration in AAD using CIBERSORTx and analyzed the correlations between immune cells and hub genes in both the training and validation sets.

Results: Sixty-one integrated DEGs were identified. The top 10 hub genes were selected from the PPI network, and 140 biological process (BP) terms and 12 pathways were enriched among the top 10 hub genes. The proportions of monocytes and macrophages were significantly higher in AAD tissues than in normal tissues. Notably, this result was consistent in the training set and the validation set. In addition, we found that among the hub genes, CA9, CXCL5, GDF15, VEGFA, CCL20, HMOX1, and SPP1 were positively correlated with CD14, a cell marker of monocytes, while CA9, CXCL5, GDF15, and VEGFA were positively correlated with CD68, a cell marker of macrophages in the training set. Finally, according to the results of the GO and KEGG analysis of hub genes, we found that the monocyte/macrophage-related genes were involved in immune-inflammatory responses through degradation of the extracellular matrix, endothelial cell apoptosis, hypoxia and the interaction of cytokines and chemokines.

Conclusion: The monocyte-macrophage system plays a major role in immune-inflammatory responses in the development of AAD. Several hub genes are involved in this process via diverse mechanisms.

Patterns of Immune Infiltration and the Key Immune-Related Genes in Acute Type A Aortic Dissection in Bioinformatics Analyses

Background

Immune-inflammatory mechanisms contribute greatly to the complex process leading to type A aortic dissection (TAAD). This study aims to explore immune infiltration and key immune-related genes in acute TAAD.

Methods

ImmuCellAI algorithm was applied to analyze patterns of immune infiltration in TAAD samples and normal aortic vessel samples in the GSE153434 dataset. Differentially expressed genes (DEGs) were screened. Immune-related genes were obtained from overlapping DEGs of GSE153434 and immune genes of the ImmPort database. The hub genes were obtained based on the protein–protein interaction (PPI) network. The hub genes in TAAD were validated in the GSE52093 dataset. The correlation between the key immune-related genes and infiltrating immune cells was further analyzed.

Results

In the study, the abundance of macrophages, neutrophils, natural killer T cells (NKT cells), natural regulatory T cells (nTreg), T-helper 17 cells (Th17 cells) and monocytes was increased in TAAD samples, whereas that of dendritic cells (DCs), CD4 T cells, central memory T cells (Tcm), mucosa associated invariant T cells (MAIT cells) and B cells was decreased. Interleukin 6 (IL-6), C-C motif chemokine ligand 2 (CCL2) and hepatocyte growth factor (HGF) were identified and validated in the GSE52093 dataset as the key immune-related genes. Furthermore, IL-6, CCL2 and HGF were correlated with different types of immune cells.

Conclusion

In conclusion, several immune cells such as macrophages, neutrophils, NKT cells, and nTreg may be involved in the development of TAAD. IL-6, CCL2 and HGF were identified and validated as the key immune-related genes of TAAD via bioinformatics analyses. The key immune cells and immune-related genes have the potential to be developed as targets of prevention and immunotherapy for patients with TAAD.

Ying and Yang of Stat3 in pathogenesis of aortic dissection

Aortic dissection (AD) is a medical emergency, in which acute destruction of aortic wall occurs with unknown etiology. Recent studies have uncovered the critical role of inteleukin-6 (IL-6) and inflammatory cells including macrophages in the disease mechanism of AD. IL-6 activates janus kinase and signal transducer and activator of transcription 3 (STAT3) to alter the gene expression program in many cell types, thus regulating various aspects of inflammatory response. We found that in human AD tissue, STAT3 was activated in infiltrating macrophages and in medial smooth muscle cells (SMCs), suggesting that STAT3 may regulate the response of these cell types. However, it is unknown how Stat3 regulates the cell type-specific response in pathogenesis of AD. The role of STAT3 was examined in genetically modified mice in which STAT3 sensitivity was enhanced specifically in macrophages or in SMCs by tissue-specific deletion of suppressor of cytokine signaling 3 (Socs3), a negative regulator of STAT3. Macrophage-specific deletion of Socs3 caused acute enhancement of STAT3 activation, M1-dominant differentiation of macrophages, suppression of tissue repair response of SMCs, and exaggerated AD. In contrast, SMC-specific deletion of Socs3 caused chronic STAT3 activation and low-grade inflammatory response in aortic walls, activation of fibroblasts, M2-dominant differentiation of macrophages, increase in adventitial collagen deposition, resulting in the protection of aorta from AD by reinforcing the tensile strength of the aortic walls. Therefore, STAT3 regulates the balance between the destruction and the reinforcement of the aortic tissue, depending on the cell types and the time course of STAT3 activation, which ultimately regulates the development of AD. Elucidating such a dynamic mechanism to regulate the aortic tissue integrity would be essential to decipher the molecular pathogenesis of AD.

Angiotensin II Infusion Leads to Aortic Dissection in LRP8 Deficient Mice

Myeloid cells are crucial for the development of vascular inflammation. Low-density lipoprotein receptor-related protein 8 (LRP8) or Apolipoprotein E receptor 2 (ApoER2), is expressed by macrophages, endothelial cells and platelets and has been implicated in the development of cardiovascular diseases. Our aim was to evaluate the role of LRP8, in particular from immune cells, in the development of vascular inflammation. Methods. LRP8^+/+ and LRP8^−/− mice (on B6;129S background) were infused with angiotensin II (AngII, 1 mg/kg/day for 7 to 28 day) using osmotic minipumps. Blood pressure was recorded using tail cuff measurements. Vascular reactivity was assessed in isolated aortic segments. Leukocyte activation and infiltration were assessed by flow cytometry of aortic tissue and intravital videomicroscopy imaging. Histological analysis of aortic sections was conducted using sirius red staining. Results. AngII infusion worsened endothelial-dependent vascular relaxation and immune cells rolling and adherence to the carotid artery in both LRP8^+/+ as well as LRP8^−/− mice. However, only LRP8^−/− mice demonstrated a drastically increased mortality rate in response to AngII due to aortic dissection. Bone marrow transplantation revealed that chimeras with LRP8 deficient myeloid cells phenocopied LRP8^−/− mice. Conclusion. AngII-infused LRP8 deficient mice could be a useful animal model to study aortic dissection reflecting the lethality of this disease in humans.

Deficiency of CD44 prevents thoracic aortic dissection in a murine model

Thoracic aortic dissection (TAD) is a life-threatening vascular disease. We showed that CD44, a widely distributed cell surface adhesion molecule, has an important role in inflammation. In this study, we examined the role of CD44 in the development of TAD. TAD was induced by the continuous infusion of β-aminopropionitrile (BAPN), a lysyl oxidase inhibitor, and angiotensin II (AngII) for 7 days in wild type (WT) mice and CD44 deficient (CD44^-/-) mice. The incidence of TAD in CD44^-/- mice was significantly reduced compared with WT mice (44% and 6%, p < 0.01). Next, to evaluate the initial changes, aortic tissues at 24 hours after BAPN/AngII infusion were examined. Neutrophil accumulation into thoracic aortic adventitia in CD44^-/- mice was significantly decreased compared with that in WT mice (5.7 ± 0.3% and 1.6 ± 0.4%, p < 0.01). In addition, BAPN/AngII induced interleukin-6, interleukin-1β, matrix metalloproteinase-2 and matrix metalloproteinase-9 in WT mice, all of which were significantly reduced in CD44^−/− mice (all p < 0.01). In vitro transmigration of neutrophils from CD44^−/− mice through an endothelial monolayer was significantly decreased by 18% compared with WT mice (p < 0.01). Our findings indicate that CD44 has a critical role in TAD development in association with neutrophil infiltration into adventitia.

MRTF-A promotes angiotensin II-induced inflammatory response and aortic dissection in mice

Aortic dissection (AD) is a major cause of acute aortic syndrome with high mortality due to the destruction of aortic walls. Although recent studies indicate the critical role of inflammation in the disease mechanism of AD, it is unclear how inflammatory response is initiated. Here, we demonstrate that myocardin-related transcription factor A (MRTF-A), a signal transducer of humoral and mechanical stress, plays an important role in pathogenesis of AD in a mouse model. A mouse model of AD was created by continuous infusion of angiotensin II (AngII) that induced MRTF-A expression and caused AD in 4 days. Systemic deletion of Mrtfa gene resulted in a marked suppression of AD development. Transcriptome and gene annotation enrichment analyses revealed that AngII infusion for 1 day caused pro-inflammatory and pro-apoptotic responses before AD development, which were suppressed by Mrtfa deletion. AngII infusion for 1 day induced pro-inflammatory response, as demonstrated by expressions of Il6, Tnf, and Ccl2, and apoptosis of aortic wall cells, as detected by TUNEL staining, in an MRTF-A-dependent manner. Pharmacological inhibition of MRTF-A by CCG-203971 during AngII infusion partially suppressed AD phenotype, indicating that acute suppression of MRTF-A is effective in preventing the aortic wall destruction. These results indicate that MRTF-A transduces the stress of AngII challenge to the pro-inflammatory and pro-apoptotic responses, ultimately leading to AD development. Intervening this pathway may represent a potential therapeutic strategy.

Factors related to white blood cell elevation in acute type A aortic dissection

Aortic dissection may induce a systemic inflammatory reaction. The etiological backgrounds for elevation of the white blood cell count remain to be clarified. In 466 patients with acute type A aortic dissection treated surgically within 48 hours of symptom onset, the etiologic background of an elevated admission white blood cell count and the effect of such elevation on outcomes were assessed retrospectively. Patients’ white blood cell count differed significantly in relation to the extent of dissection, with a median (25th, 75th percentile) white blood cell count of 10.4 (8.1, 13.9) x 10³/μL for dissection confined to the ascending aorta, 10.5 (8.2,13.) 10³/μL for dissection extending to the aortic arch/descending aorta, 11.1 (8.2, 13.7) x 10³/μL for extension to the abdominal aorta, and 13.3 (9.8, 15.9) x 10³/μL for extension to the iliac artery (p<0.001). With 11.0 x 10^3/μL used as the cut-off value for white blood cell count elevation, multivariable analysis showed current smoking (p<0.001; odds ratio, 2.79), dissection extending to the iliac artery (p = 0.006; odds ratio, 1.79), age (p = 0.007, odds ratio, 0.98), and no coronary ischemia (p = 0.027, odds ratio, 2.22) to be factors related to the elevated white blood cell count. Mean age differed significantly between patients with and without an elevated white blood cell count (62.3 vs. 68.3 years, p <0.001). Although in-hospital mortality was similar (7.5% vs.10.9%, p = 0.19), 5-year survival was lower in patients without an elevated count (85.7% vs. 78.6%, p = 0.019), reflecting their more advanced age. In conclusion, our data suggest that dissection morphology and patient age influence the acute phase systemic inflammatory response associated with an elevated white blood cell count in patients with ATAAD. A better understanding of this relation may help optimize diagnosis and perioperative care.