Causal Role for Neutrophil Elastase in Thoracic Aortic Dissection in Mice

Extracellular matrix in vascular homeostasis and disease

The extracellular matrix is an essential component and constitutes a dynamic microenvironment of the vessel wall with an indispensable role in vascular homeostasis and disease. From early development through to ageing, the vascular extracellular matrix undergoes various biochemical and biomechanical alterations in response to diverse environmental cues and exerts precise regulatory control over vessel remodelling. Advances in novel technologies that enable the comprehensive evaluation of extracellular matrix components and cell-matrix interactions have led to the emergence of therapeutic strategies that specifically target this fine-tuned network. In this Review, we explore various aspects of extracellular matrix biology in vascular development, disorders and ageing, emphasizing the effect of the extracellular matrix on disease initiation and progression. Additionally, we provide an overview of the potential therapeutic implications of targeting the extracellular matrix microenvironment in vascular diseases.

Calpain inhibition as a novel therapeutic strategy for aortic dissection with acute lower extremity ischemia

BACKGROUND

Aortic dissection (AD) patients with malperfusion present significant challenges and are associated with high postoperative mortality rates. Limited data exist regarding the management of patients with AD and acute lower extremity ischemia. Early diagnosis of the extent of malperfusion and timely intervention are critical for improving patient prognosis.

METHODS

A total of 104 patients diagnosed with AD were enrolled in this observational retrospective study, of which 11 (10.6%) presented with lower limb ischemia (LLI). A comparative analysis was conducted on the clinical data of the AD group and the AD + LLI group. Plasma concentrations of SBDP145, a specific indicator of Calpain activity, were quantified in Control, AD, and AD + LLI groups using ELISA. To explore the role of Calpain in LLI and AD, pharmacological inhibition with Calpeptin and transgenic mice overexpressing calpastatin (Tg-CAST) were utilized in mouse models. RNA sequencing and functional assays were employed to identify the downstream effectors of Calpain.

RESULTS

Patients in the AD + LLI group exhibited significantly elevated leukocyte counts, percentages of neutrophils and lymphocytes, as well as increased serum levels of AST, creatinine, total cholesterol, low-density lipoprotein, uric acid, and creatine kinase compared to those in the AD group. Furthermore, the mean calcium ion concentration and Ca2+-dependent Calpain activation were significantly higher in the AD + LLI patients. Both endogenous and exogenous Calpain inhibitors effectively promoted the restoration of blood flow to ischemic hind limbs by inhibiting the inflammatory response and promoting vascular regeneration. Additionally, Calpain inhibition prevented the onset and progression of AD. RNA sequencing and Western Blot assays demonstrated that Calpain inhibition significantly increased levels of Fabp3, which is involved in the ischemia-induced fatty acid metabolism pathway.

CONCLUSIONS

Inhibition of Calpain has been demonstrated to decrease the incidence of AD and enhance the restoration of blood flow perfusion in ischemic lower extremities. This effect may be mediated by the upregulation of Fabp3. These findings highlight the potential for targeted interventions against Calpain as a novel therapeutic strategy in the treatment of cardiovascular disease.

Fibrin induces infiltration of macrophages and neutrophils via integrin αMβ2 and triggers aortic dissection

BACKGROUND AND PURPOSE

Infiltration of macrophages and neutrophils plays a crucial role in the occurrence of aortic dissection (AD), while the mechanism elucidating their infiltration remains unknown. The present study aimed to delineate the underlying mechanism and provide a potential therapeutic strategy to attenuate AD progression.

EXPERIMENTAL APPROACH

A model of AD was established in male mice using β-aminopropionitrile and angiotensin II. Proteomic analysis, histological evaluation, flow cytometry, western blot, multiple fluorescence staining and adhesion assays were used to evaluate fibrin and inflammatory cells during AD progression. Fibrinogen-lowering drugs and fibrinogen γ-chain knockout (Fgg+/-) mice were also used to evaluate the fibrin-integrin αMβ2 interaction.

KEY RESULTS

Fibrin deposition was confirmed by proteomic analysis and histological staining, accompanied by infiltration of macrophages and neutrophils detected by flow cytometry during the progression of AD. After confirming that macrophages and neutrophils infiltrated at the sites where fibrin was deposited by immunofluorescence, an association between fibrin and the integrin αMβ2 was disclosed using protein-protein interaction analysis and immunofluorescence. The pivotal role of interactions between fibrin and integrin αMβ2 in AD progression was confirmed by cell adhesion in vitro, down-regulation of fibrin using batroxobin and Fgg+/- mice in vivo. The relevance of fibrin and integrin αMβ2 was also found in patients with AD.

CONCLUSION AND IMPLICATIONS

Fibrin plays a crucial role in triggering AD through recruiting macrophages and neutrophils via integrin αMβ2. Regulation of fibrin deposition or inhibition of the interaction between fibrin and integrin αMβ2 provide a potential therapy against AD.

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.

Elevated levels of neutrophils with a pro-inflammatory profile in Turner syndrome across karyotypes

Turner syndrome (TS) presents with multiple karyotypes, including 45,X monosomy and variants such as isochromosomes and mosaicism, and is characterized by several co-morbidities, including metabolic conditions and autoimmunity. Here, we investigated the genomic landscapes across a range of karyotypes. We show that TS have a common autosomal methylome and transcriptome, despite distinct karyotypic variations. All TS individuals lacked the X chromosome p-arm, and XIST expression from the q-arm did not affect the autosomal transcriptome or methylome, highlighting the critical role of the missing p-arm with its pseudoautosomal region 1. Furthermore, we show increased levels of neutrophils and increased neutrophil activation. The increase in neutrophils was linked to TS clinical traits and to increased expression of the X-Y homologous gene TBL1X, suggesting a genetic basis, which may lead to neutrophil-driven inflammatory stress in TS. Identifying TS individuals with increased neutrophil activation could potentially mitigate the progression towards more severe metabolic issues.

Integrative Bioinformatics Analysis to Identify Key Ferroptosis-Related Genes and Immune Infiltration in Aortic Aneurysm and Dissection: Implication of PTGS2

Background

Aortic aneurysm and dissection (AAD) represent a highly lethal cardiovascular condition. Ferroptosis has recently been implicated in AAD development and progression. However, ferroptosis-related genes (FRGs) have not been systematically identified and verified in AAD.

Methods and Results

Seven human AAD datasets downloaded from Gene Expression Omnibus were analyzed, and 113 potential AAD-related FRGs were identified. Function enrichment analyses revealed that the FRGs were mainly associated with responses to chemical stress and cytokine signaling in the immune system. Protein-protein interaction network analyses identified 8 hub FRGs including EZH2, EGFR, HIF1A, IL6, PTGS2, MAPK1, IL1B and SRC. All these FRGs were significantly increased in patients with aortic aneurysm. Additionally, immune cell infiltration analyses revealed these FRGs were strongly correlated with the higher CD4+ Tem and macrophages fraction in AAD patients. Particularly, increased expression of PTGS2 in AAD patients was further validated using our newly collected clinical aortic specimens. Importantly, we found that PTGS2 knockdown could reduce the expression of MMP9 and MMP2 but increase GPX4 expression in macrophages. Conversely, while PTGS2 overexpression upregulated MMP9 and MMP2 expression but downregulated GPX4 expression, the regulatory effects of PTGS2 on these genes were largely blunted by ferroptosis inhibitors. Functionally, administration of celecoxib, a PTGS2-specific inhibitor, into mice significantly reduced β-aminopropionitrile-induced AAD development and progression.

Conclusion

Through an integrative bioinformatics analysis, we have identified multiple key AAD-related FRGs including PTGS2. Functional studies also suggest a functional role of PTGS2 in ferroptosis and AAD development, offering novel insights into pathogenesis of human AAD.

Recent advances in targeted therapy for inflammatory vascular diseases

Vascular diseases constitute a significant contributor to worldwide mortality rates, placing a substantial strain on healthcare systems and socio-economic aspects. They are closely associated with inflammatory responses, as sustained inflammation could impact endothelial function, the release of inflammatory mediators, and platelet activation, thus accelerating the progression of vascular diseases. Consequently, directing therapeutic efforts towards mitigating inflammation represents a crucial approach in the management of vascular diseases. Traditional anti-inflammatory medications may have extensive effects on multiple tissues and organs when absorbed through the bloodstream. Conversely, treatments targeting inflammatory vascular diseases, such as monoclonal antibodies, drug-eluting stents, and nano-drugs, can achieve more precise effects, including precise intervention, minimal non-specific effects, and prolonged efficacy. In addition, personalized therapy is an important development trend in targeted therapy for inflammatory vascular diseases. Leveraging advanced simulation algorithms and clinical trial data, treatment strategies are gradually being personalized based on patients' genetic, biomarker, and clinical profiles. It is expected that the application of precision medicine in the field of vascular diseases will have a broader future. In conclusion, targeting therapies offer enhanced safety and efficacy compared to conventional medications; investigating novel targeting therapies and promoting clinical transformation may be a promising direction in improving the prognosis of patients with inflammatory vascular diseases. This article reviews the pathogenesis of inflammatory vascular diseases and presents a comprehensive overview of the potential for targeted therapies in managing this condition.

Independent and Interactive Roles of Immunity and Metabolism in Aortic Dissection

Aortic dissection (AD) is a cardiovascular disease that seriously endangers the lives of patients. The mortality rate of this disease is high, and the incidence is increasing annually, but the pathogenesis of AD is complicated. In recent years, an increasing number of studies have shown that immune cell infiltration in the media and adventitia of the aorta is a novel hallmark of AD. These cells contribute to changes in the immune microenvironment, which can affect their own metabolism and that of parenchymal cells in the aortic wall, which are essential factors that induce degeneration and remodeling of the vascular wall and play important roles in the formation and development of AD. Accordingly, this review focuses on the independent and interactive roles of immunity and metabolism in AD to provide further insights into the pathogenesis, novel ideas for diagnosis and new strategies for treatment or early prevention of AD.