BAPN-induced rodent model of aortic dissecting aneurysm and related complications

Cannabidiol protects against acute aortic dissection by inhibiting macrophage infiltration and PMAIP1-induced vascular smooth muscle cell apoptosis

Acute aortic dissection (AAD) progresses rapidly and is associated with high mortality; therefore, there remains an urgent need for pharmacological agents that can protect against AAD. Herein, we examined the therapeutic effects of cannabidiol (CBD) in AAD by establishing a suitable mouse model. In addition, we performed human AAD single-cell RNA sequencing and mouse AAD bulk RNA sequencing to elucidate the potential underlying mechanism of CBD. Pathological assays and in vitro studies were performed to verify the results of the bioinformatic analysis and explore the pharmacological function of CBD. In a β-aminopropionitrile (BAPN)-induced AAD mouse model, CBD reduced AAD-associated morbidity and mortality, alleviated abnormal enlargement of the ascending aorta and aortic arch, and suppressed macrophage infiltration and vascular smooth muscle cell (VSMC) apoptosis. Bioinformatic analysis revealed that the pro-apoptotic gene PMAIP1 was highly expressed in human and mouse AAD samples, and CBD could inhibit Pmaip1 expression in AAD mice. Using human aortic VSMCs (HAVSMCs) co-cultured with M1 macrophages, we revealed that CBD alleviated HAVSMCs mitochondrial-dependent apoptosis by suppressing the BAPN-induced overexpression of PMAIP1 in M1 macrophages. PMAIP1 potentially mediates HAVSMCs apoptosis by regulating Bax and Bcl2 expression. Accordingly, CBD reduced AAD-associated morbidity and mortality and mitigated the progression of AAD in a mouse model. The CBD-induced effects were potentially mediated by suppressing macrophage infiltration and PMAIP1 (primarily expressed in macrophages)-induced VSMC apoptosis. Our findings offer novel insights into M1 macrophages and HAVSMCs interaction during AAD progression, highlighting the potential of CBD as a therapeutic candidate for AAD treatment.

Inducing aortic aneurysm/dissection in zebrafish: evaluating the efficacy of β-Aminopropionic Nitrile as a model

Aortic aneurysm/dissection (AAD) poses a life-threatening cardiovascular emergency with complex mechanisms and a notably high mortality rate. Zebrafish (Danio rerio) serve as valuable models for AAD due to the conservation of their three-layered arterial structure and genome with that of humans. However, the existing studies have predominantly focused on larval zebrafish, leaving a gap in our understanding of adult zebrafish. In this study, we utilized β-Aminopropionic Nitrile (BAPN) impregnation to induce AAD in both larval and adult zebrafish. Following induction, larval zebrafish exhibited a 28% widening of the dorsal aortic diameter (p < 0.0004, n = 10) and aortic arch malformations, with a high malformation rate of 75% (6/8). Conversely, adult zebrafish showed a 41.67% (5/12) mortality rate 22 days post-induction. At this time point, the dorsal aortic area had expanded by 2.46 times (p < 0.009), and the vessel wall demonstrated significant thickening (8.22 ± 2.23 μM vs. 26.38 ± 10.74 μM, p < 0.05). Pathological analysis revealed disruptions in the smooth muscle layer, contributing to a 58.33% aneurysm rate. Moreover, the expression levels of acta2, tagln, cnn1a, and cnn1b were decreased, indicating a weakened contractile phenotype. Transcriptome sequencing showed a significant overlap between the molecular features of zebrafish tissues post-BAPN treatment and those of AAD patients. Our findings present a straightforward and practical method for generating AAD models in both larval and adult zebrafish using BAPN.

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.

Tomo-seq identifies NINJ1 as a potential target for anti-inflammatory strategy in thoracic aortic dissection

BACKGROUND

Thoracic aortic dissection (TAD) is a life-threatening disease caused by an intimal tear in the aorta. The histological characteristics differ significantly between the tear area (TA) and the distant area. Previous studies have emphasized that certain specific genes tend to cluster at the TA. Obtaining a thorough understanding of the precise molecular signatures near the TA will assist in discovering therapeutic strategies for TAD.

METHODS

We performed a paired comparison of the pathological patterns in the TA with that in the remote area (RA). We used Tomo-seq, genome-wide transcriptional profiling with spatial resolution, to obtain gene expression signatures spanning from the TA to the RA. Samples from multiple sporadic TAD patients and animal models were used to validate our findings.

RESULTS

Pathological examination revealed that the TA of TAD exhibited more pronounced intimal hyperplasia, media degeneration, and inflammatory infiltration compared to the RA. The TA also had more apoptotic cells and CD31+α-SMA+ cells. Tomo-seq revealed four distinct gene expression patterns from the TA to the RA, which were inflammation, collagen catabolism, extracellular matrix remodeling, and cell stress, respectively. The spatial distribution of genes allowed us to identify genes that were potentially relevant with TAD. NINJ1 encoded the protein-mediated cytoplasmic membrane rupture, regulated tissue remodeling, showed high expression levels in the tear area, and co-expressed within the inflammatory pattern. The use of short hairpin RNA to reduce NINJ1 expression in the beta-aminopropionitrile-induced TAD model led to a significant decrease in TAD formation. Additionally, it resulted in reduced infiltration of inflammatory cells and a decrease in the number of CD31+α-SMA+ cells. The NINJ1-neutralizing antibody also demonstrated comparable therapeutic effects and can effectively impede the formation of TAD.

CONCLUSIONS

Our study showed that Tomo-seq had the advantage of obtaining spatial expression information of TAD across the TA and the RA. We pointed out that NINJ1 may be involved in inflammation and tissue remodeling, which played an important role in the formation of TAD. NINJ1 may serve as a potential therapeutic target for TAD.

Echinatin maintains glutathione homeostasis in vascular smooth muscle cells to protect against matrix remodeling and arterial stiffening

Decreased vascular compliance of the large arteries as indicated by increased pulse wave velocity is shown to be associated with atherosclerosis and the related cardiovascular events. The positive correlation between arterial stiffening and disease progression derives a hypothesis that softening the arterial wall may protect against atherosclerosis, despite that the mechanisms controlling the cellular pathological changes in disease progression remain unknown. Here, we established a mechanical-property-based screening to look for compounds alleviating the arterial wall stiffness through their actions on the interaction between vascular smooth muscle cells (VSMCs) and the wall extracellular matrix (ECM). We found that echinatin, a chalcone preferentially accumulated in roots and rhizomes of licorice (Glycyrrhiza inflata), reduced the stiffness of ECM surrounding cultured VSMCs. We examined the potential beneficial effects of echinatin on mitigating arterial stiffening and atherosclerosis, and explored the mechanistic basis by which the compound exert the effects. Administration of echinatin in mice fed on an adenine diet and in hyperlipidemia mice subjected to 5/6 nephrectomy mitigated arterial stiffening and atherosclerosis. Mechanistic insights were gained from the RNA-sequencing results showing that echinatin upregulated the expression of glutamate cysteine ligases (GCLs), both the catalytic (GCLC) and modulatory (GCLM) subunits. Further study indicated that upregulation of GCLC/GCLM in VSMCs by echinatin maintains the homeostasis of glutathione (GSH) metabolism; adequate availability of GSH is critical for counteracting arterial stiffening. As a consequence of regulating the GSH synthesis, echinatin inhibits ferroptosis and matrix remodeling that being considered two contributors of arterial stiffening and atherosclerosis. These data demonstrate a pivotal role of GSH dysregulation in damaging the proper VSMC-ECM interaction and uncover a beneficial activity of echinatin in preventing vascular diseases.

PM2.5 exposure exacerbates mice thoracic aortic aneurysm and dissection by inducing smooth muscle cell apoptosis via the MAPK pathway

Air pollution is a major public health concern worldwide. Exposure to fine particulate matter (PM2.5) is closely associated with cardiovascular diseases. However, the effect of PM2.5 exposure on thoracic aortic aneurysm and dissection (TAAD) has not been fully elucidated. Diesel exhaust particulate (DEP) is an important component of PM2.5, which causes health effects and is closely related to the incidence of cardiovascular disease. In the current study, we found that DEP exposure increased the incidence of aortic dissection (AD) in β-aminopropionitrile (BAPN)-induced thoracic aortic aneurysm (TAA). In addition, exposure to PM2.5 increased the diameter of the thoracic aorta in mice models. The number of apoptotic cells increased in the aortic wall of PM2.5-treated mice, as did the protein expression level of BAX/Bcl2 and cleaved caspase3/caspase3. Using a rhythmically stretching aortic mechanical simulation model, fluorescent staining indicated that PM2.5 administration could induce mitochondrial dysfunction and increase reactive oxygen species (ROS) levels in human aortic smooth muscle cells (HASMCs). Furthermore, ERK1/2 mitogen-activated protein kinase (MAPK) signaling pathways participated in the apoptosis of HASMCs after PM2.5 exposure. Therefore, we concluded that PM2.5 exposure could exacerbate the progression of TAAD, which could be induced by the increased apoptosis in HASMCs through the ERK1/2 MAPK signaling pathway.

Fibroblast-Secreted Phosphoprotein 1 Mediates Extracellular Matrix Deposition and Inhibits Smooth Muscle Cell Contractility in Marfan Syndrome Aortic Aneurysm

Fibrillin 1 (Fbn1) mutation causes Marfan syndrome (MFS) with thoracic aortic aneurysm (TAA) as the main complication. The mechanisms for extracellular matrix (ECM) homeostasis disruption in MFS TAA are unclear. Here, we found ECM-related gene secreted phosphoprotein 1 (Spp1) increased in Fbn1^C1041G/+ mice using transcriptome sequencing and a distinct fibroblast subcluster with Spp1 as the strongest marker was identified with analysis of the MFS mouse aortic single-cell sequencing dataset. Immunostaining confirmed elevated Spp1 in adventitial fibroblasts, and Spp1 might regulate fibroblast and smooth muscle cell (SMC) communication primarily through Itga8/Itgb1. Then, we observed Spp1 reduced contractile genes Acta2 and Tagln expression in SMCs and increased collagen expression in fibroblasts, which might contribute to TAA development. Finally, we also found elevated SPP1 plasma level was associated with an increased risk of TAA in patients. Therefore, SPP1 may serve as a biomarker and therapeutic target for TAA.