Role of Macrophage Socs3 in the Pathogenesis of Aortic Dissection

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.

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.

Macrophage in Sporadic Thoracic Aortic Aneurysm and Dissection: Potential Therapeutic and Preventing Target

Thoracic aortic aneurysm and dissection (TAAD) is a life-threatening cardiovascular disorder lacking effective clinical pharmacological therapies. The underlying molecular mechanisms of TAAD still remain elusive with participation of versatile cell types and components including endothelial cells (ECs), smooth muscle cells (SMCs), fibroblasts, immune cells, and the extracellular matrix (ECM). The main pathological features of TAAD include SMC dysfunction, phenotypic switching, and ECM degradation, which is closely associated with inflammation and immune cell infiltration. Among various types of immune cells, macrophages are a distinct participator in the formation and progression of TAAD. In this review, we first highlight the important role of inflammation and immune cell infiltration in TAAD. Furthermore, we discuss the role of macrophages in TAAD from the aspects of macrophage origination, classification, and functions. On the basis of experimental and clinical studies, we summarize key regulators of macrophages in TAAD. Finally, we review how targeting macrophages can reduce TAAD in murine models. A better understanding of the molecular and cellular mechanisms of TAAD may provide novel insights into preventing and treating the condition.

Socs3b regulates the development and function of innate immune cells in zebrafish

Introduction

Suppressor of cytokine signaling 3 (SOCS3) is a critical component of the negative feedback regulation that controls signaling by cytokines and other factors thereby ensuring that important processes such as hematopoiesis and inflammation occur at appropriate levels.

Methods

To gain further insights into SOCS3 function, the zebrafish socs3b gene was investigated through analysis of a knockout line generated using CRISPR/Cas9-mediated genome editing.

Results

Zebrafish socs3b knockout embryos displayed elevated numbers of neutrophils during primitive and definitive hematopoiesis but macrophage numbers were not altered. However, the absence of socs3b reduced neutrophil functionality but enhanced macrophage responses. Adult socs3b knockout zebrafish displayed reduced survival that correlated with an eye pathology involving extensive infiltration of neutrophils and macrophages along with immune cell dysregulation in other tissues.

Discussion

These findings identify a conserved role for Socs3b in the regulation of neutrophil production and macrophage activation.

Use of Anti-Thrombotic Drugs and In-Hospital Mortality in Acute Aortic Dissection Patients

Acute aortic dissection occurs due to a primary tear in the aortic intima, with blood from the aortic lumen entering the adjacent diseased media. In the clinical setting, practitioners often hesitate before the use of anti-thrombotic drugs in the acute phase of aortic dissection. Therefore, we examined the clinical course in patients who had already received antithrombotic therapies at the onset of acute aortic dissection, and who were given anti-thrombotic drugs in the acute phase during hospitalization. We retrospectively enrolled 685 consecutive patients with acute aortic dissection (type A/B: 454/231), who were transferred to Kurume University Hospital from 2004 to 2020. In types A and B, there were no significant differences between in-hospital mortality with or without antithrombotic therapies at the onset (14.3% vs. 16.4%, p = 0.66 in type A, 2.6% vs. 7.3%, p = 0.29 in type B). Patients in type A who survived more than a day and were treated with anti-thrombotic drugs during hospitalization had significantly lower in-hospital mortality compared with those who received no anti-thrombotic drugs in the acute phase (2.2% vs. 16.1%, p < 0.001), while there was no significant difference between in-hospital mortality in the two type-B groups (2.4% vs. 4.9%, p = 0.48). Although there were variations in response among patients with acute aortic dissection, anti-thrombotic drugs did not worsen in-hospital mortality for patients with acute aortic dissection, indicating that medical staff should not hesitate to administer anti-thrombotic drugs if indicated.

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.

Association Between Preoperative Monocyte to High-Density Lipoprotein Ratio on In-hospital and Long-Term Mortality in Patients Undergoing Endovascular Repair for Acute Type B Aortic Dissection

Aims: The monocyte to high-density lipoprotein ratio (MHR), a novel marker of inflammation and cardiovascular events, has recently been found to facilitate the diagnosis of acute aortic dissection. This study aimed to assess the association of preoperative MHR with in-hospital and long-term mortality after thoracic endovascular aortic repair (TEVAR) for acute type B aortic dissection (TBAD).

Methods: We retrospectively evaluated 637 patients with acute TBAD who underwent TEVAR from a prospectively maintained database. Multivariable logistic and cox regression analyses were conducted to assess the relationship between preoperative MHR and in-hospital as well as long-term mortality. For clinical use, MHR was modeled as a continuous variable and a categorical variable with the optimal cutoff evaluated by receiver operator characteristic curve for long-term mortality. Propensity score matching was used to diminish baseline differences and subgroups analyses were conducted to assess the robustness of the results.

Results: Twenty-one (3.3%) patients died during hospitalization and 52 deaths (8.4%) were documented after a median follow-up of 48.1 months. The optimal cutoff value was 1.13 selected according to the receiver operator characteristic curve (sensitivity 78.8%; specificity 58.9%). Multivariate analyses showed that MHR was independently associated with either in-hospital death [odds ratio (OR) 2.11, 95% confidence interval (CI) 1.16-3.85, P = 0.015] or long-term mortality [hazard ratio (HR) 1.78, 95% CI 1.31-2.41, P < 0.001). As a categorical variable, MHR > 1.13 remained an independent predictor of in-hospital death (OR 4.53, 95% CI 1.44-14.30, P = 0.010) and long-term mortality (HR 4.16, 95% CI 2.13-8.10, P < 0.001). Propensity score analyses demonstrated similar results for both in-hospital death and long-term mortality. The association was further confirmed by subgroup analyses.

Conclusions: MHR might be useful for identifying patients at high risk of in-hospital and long-term mortality, which could be integrated into risk stratification strategies for acute TBAD patients undergoing TEVAR.

Neuraminidase 1 Exacerbating Aortic Dissection by Governing a Pro-Inflammatory Program in Macrophages

Inflammation plays an important role in aortic dissection (AD). Macrophages are critically involved in the inflammation after aortic injury. Neuraminidases (NEUs) are a family of enzymes that catalyze the cleavage of terminal sialic acids from glycoproteins or glycolipids, which is emerging as a regulator of macrophage-associated immune responses. However, the role of neuraminidase 1 (NEU1) in pathological vascular remodeling of AD remains largely unknown. This study sought to characterize the role and identify the potential mechanism of NEU1 in pathological aortic degeneration. After β-aminopropionitrile monofumarate (BAPN) administration, NEU1 elevated significantly in the lesion zone of the aorta. Global or macrophage-specific NEU1 knockout (NEU1 CKO) mice had no baseline aortic defects but manifested improved aorta function, and decreased mortality due to aortic rupture. Improved outcomes in NEU1 CKO mice subjected to BAPN treatment were associated with the ameliorated vascular inflammation, lowered apoptosis, decreased reactive oxygen species production, mitigated extracellular matrix degradation, and improved M2 macrophage polarization. Furthermore, macrophages sorted from the aorta of NEU1 CKO mice displayed a significant increase of M2 macrophage markers and a marked decrease of M1 macrophage markers compared with the controls. To summarize, the present study demonstrated that macrophage-derived NEU1 is critical for vascular homeostasis. NEU1 exacerbates BAPN-induced pathological vascular remodeling. NEU1 may therefore represent a potential therapeutic target for the treatment of AD.

Reversal of elastase-induced abdominal aortic aneurysm following the delivery of nanoparticle-based pentagalloyl glucose (PGG) is associated with reduced inflammatory and immune markers

OBJECTIVE

An Abdominal aortic aneurysm (AAA), a deadly disease in elderly population, is featured by expansion of aortic diameter, degradation and weakening of vasculature. Its common and significant characteristics are disarray and inflammation in vasculature. We tested the hypothesis that the reversal of abdominal aortic aneurysm by pentagalloyl glucose-loaded nanoparticles (PGG-NPs) therapy that targets degraded elastin suppresses inflammatory and immune markers to ameliorate the pathophysiology of the disease in advance stage aneurysm in a porcine pancreatic elastase (PPE)-induced mouse model of AAA.

METHODS AND RESULTS

After induction of aneurysm in pathogen-free C57BL/6 male mice by applying PPE peri-adventitially to the abdominal aorta, once a week for two doses of intravenous injections of pentagalloyl glucose-loaded nanoparticles (PGG-NPs) conjugated with elastin targeted antibody were used to reverse the aneurysms. We showed that PGG-NPs therapy could suppress infiltration of macrophages, CD8 and CD4 subsets of T cells, matrix metalloproteinases (MMPs), inflammatory cytokines interferon (IFN-γ) and interleukin (IL)-6 at the local and systemic level. Moreover, such PGG-NPs therapy increases the induction of anti-inflammatory cytokines IL-13, IL-27 and IL-10 at the local and systemic level. The therapy also led to remodeling of elastic lamina at the aneurysm site.

CONCLUSION

Nanoparticles-loaded pentagalloyl glucose therapy can be an effective treatment option against advanced stage aneurysms to reverse the disease by ameliorating inflammation and restoring arterial homeostasis.

Altered microbiota by a high-fat diet accelerates lethal myeloid hematopoiesis associated with systemic SOCS3 deficiency

The suppressors of cytokine signaling (SOCS) proteins are negative regulators of cytokine signaling required to prevent excessive cellular responses. In particular, SOCS3 is involved in the regulation of metabolic syndromes, such as obesity and diabetes, by suppressing leptin and insulin signals. SOCS3 also suppresses the inflammatory response associated with metabolic stress, but this specific role remains undefined. Wild-type mice on a high-fat diet (HFD) exhibited only fatty liver, whereas systemic deletion of SOCS3 resulted in excessive myeloid hematopoiesis and hepatic inflammation. In addition, depletion of the gut microbiota resulted in considerable improvement in excess granulopoiesis and splenomegaly, halting the progression of systemic inflammation in SOCS3KO mice on the HFD. This result suggests that intestinal dysbiosis is involved in inflammation associated with SOCS3KO. Although contributing to diet-induced obesity and fatty liver, SOCS3 is nevertheless critical to suppress excess myeloid hematopoiesis and severe systemic inflammation associated with intestinal dysbiosis on HFD.

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SOCS3 suppresses severe systemic inflammation associated with high-fat diet

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SOCS3 deficiency on high-fat diet accelerates excess myeloid hematopoiesis

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SOCS3 controls gut dysbiosis on high-fat diet

SOCS Proteins in Immunity, Inflammatory Diseases, and Immune-Related Cancer

Cytokine signaling represents one of the cornerstones of the immune system, mediating the complex responses required to facilitate appropriate immune cell development and function that supports robust immunity. It is crucial that these signals be tightly regulated, with dysregulation underpinning immune defects, including excessive inflammation, as well as contributing to various immune-related malignancies. A specialized family of proteins called suppressors of cytokine signaling (SOCS) participate in negative feedback regulation of cytokine signaling, ensuring it is appropriately restrained. The eight SOCS proteins identified regulate cytokine and other signaling pathways in unique ways. SOCS1–3 and CISH are most closely involved in the regulation of immune-related signaling, influencing processes such polarization of lymphocytes and the activation of myeloid cells by controlling signaling downstream of essential cytokines such as IL-4, IL-6, and IFN-γ. SOCS protein perturbation disrupts these processes resulting in the development of inflammatory and autoimmune conditions as well as malignancies. As a consequence, SOCS proteins are garnering increased interest as a unique avenue to treat these disorders.

AT1R Regulates Macrophage Polarization Through YAP and Regulates Aortic Dissection Incidence

Aortic dissection (AD) is one of the most fatal cardiovascular emergency. At the anatomical level, AD occurs due to the formation of intimal tears. However, the molecular mechanism underlying this phenomenon remains unknown. Angiotensin II (Ang II) is a important effector in the development of cardiovascular disease that acts through binding to angiotensin type 1 receptor (AT1R). Yes-associated protein (YAP) was recently recognized as a key protein in macrophage activation. To determine whether AT1R and YAP are involved in macrophage-induced endothelial cell (EC) inflammation and AD incidence, we co-cultured THP-1 cells and HAECs in transwell chambers under different culture conditions and apply different conditions to the AD mice model. The results showed that Ang II promoted macrophage M1 polarization and adhesion, upregulated YAP phosphorylation, and induced EC injury that was related to increased levels of multiple pro-inflammatory chemokines. Blocking AT1R function pharmacologically or by transfection with AT1R siRNA can reduce the pro-inflammatory effect induced by Ang II. In addition, siRNA knock down of YAP expression further aggravated the pro-inflammatory effects of Ang II. Treatment with ARB effectively alleviated these pro-inflammatory effects. In the mice AD model, ARB effectively reduced the incidence of AD in mice, decreased M1 macrophages infiltration and AT1R content in the aortic wall and increased the tissue content of YAP. We found that AT1R induces YAP phosphorylation through binding to Ang II, and further promotes macrophage M1 polarization and adhesion to ECs. ARB reduces the incidence of AD in mice and affect macrophage polarization in mice aorta.

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.

Diagnostic value of monocyte to high-density lipoprotein ratio in acute aortic dissection in a Chinese han population

Background: Recently, considerable evidence pointed out monocyte to high-density lipoprotein ratio (MHR) is highly related to inflammatory related diseases. We aim to explore the level of MHR in acute aortic dissection (AAD) patients and determine whether MHR can be a novel diagnostic marker of AAD. Research design and methods: A total of 228 subjects including 128 AAD patients and 110 healthy control were enrolled. MHR levels and other serum samples were obtained at admission. Results: The baseline MHR levels were significantly higher in patients with AAD (p < 0.0001). A cutoff value of MHR >0.37 was associated with a sensitivity of 86.70% and a specificity of 93.60% for AAD. MHR levels were positively correlated with the time from symptom onset (R² = 0.0318, p = 0.0003). Additionally, the area under the curve (AUC) was increased to 0.979 in patients whose time from onset of symptoms >24 h, with a sensitivity of 98.04% and a specificity of 93.64%. Multivariate logistic regression demonstrated that MHR levels, history of hypertension, and coronary artery disease (CHD) emerged as independent predictors of AAD. Expert Opinion: MHR has a high diagnostic value in AAD patients, especially in those whose time from onset of symptoms >24 h.

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.

Therapeutic Effect of Rapamycin on Aortic Dissection in Mice

Aortic dissection (AD) is a serious clinical condition that is unpredictable and frequently results in fatal outcome. Although rapamycin, an inhibitor of mechanistic target of rapamycin (mTOR), has been reported to be effective in preventing aortopathies in mouse models, its mode of action has yet to be clarified. A mouse AD model that was created by the simultaneous administration of β-aminopropionitrile (BAPN) and angiotensin II (AngII) for 14 days. Rapamycin treatment was started either at day 1 or at day 7 of BAPN+AngII challenge, and continued throughout the observational period. Rapamycin was effective both in preventing AD development and in suppressing AD progression. On the other hand, gefitinib, an inhibitor of growth factor signaling, did not show such a beneficial effect, even though both rapamycin and gefitinib suppressed cell cycle activation in AD. Rapamycin suppressed cell cycle-related genes and induced muscle development-related genes in an AD-related gene expression network without a major impact on inflammation-related genes. Rapamycin augmented the activation of Akt1, Akt2, and Stat3, and maintained the contractile phenotype of aortic smooth muscle cells. These findings indicate that rapamycin was effective both in preventing the development and in suppressing the progression of AD, indicating the importance of the mTOR pathway in AD pathogenesis.

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.

The Role of Macrophages in Aortic Dissection

Aortic dissection (AD) is a fatal disease that accounts for a large proportion of aortic-related deaths and has an incidence of about 3–4 per 100,000 individuals every year. Recent studies have found that inflammation plays an important role in the development of AD, and that macrophages are the hub of inflammation in the aortic wall. Aortic samples from AD patients reveal a large amount of macrophage infiltration. The sites of macrophage infiltration and activity vary throughout the different stages of AD, with involvement even in the tissue repair phase of AD. Angiotensin II has been shown to be an important factor in the stimulation of macrophage activity. Stimulated macrophages can secrete metalloproteinases, inflammatory factors and other substances to cause matrix destruction, smooth muscle cell apoptosis, neovascularization and more, all of which destroy the aortic wall structure. At the same time, there are a number of factors that regulate macrophages to reduce the formation of AD and induce the repair of torn aortic tissues. The aim of this review is to take a close look at the roles of macrophages throughout the course of AD disease.

Genetic Deletion of Socs3 in Smooth Muscle Cells Ameliorates Aortic Dissection in Mice

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Stat3, a major signaling molecule for proinflammatory cytokines including IL-6, was activated both in inflammatory cells and in SMC in the aortic walls of human AD and mouse AD model.

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SMC-specific deletion of Socs3 enhanced Stat3 activation in SMC, induced moderate proinflammatory response in the aortic walls, and ameliorated AD in mice.

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SmSocs3-KO aortas showed increases in fibroblasts, adventitial collagen fibers, and tensile strength of the aortic walls.

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IL-6-stimulated SMC in culture secreted humoral factor(s) that promoted proliferative response of fibroblasts.

Aortic dissection (AD) is the acute destruction of aortic wall and is reportedly induced by inflammatory response. Here we investigated the role of smooth muscle Socs3 (a negative regulator of Janus kinases/signal transducer and activator of transcription signaling) in AD pathogenesis using a mouse model generated via β-aminopropionitrile and angiotensin II infusion. Socs3 deletion specifically in smooth muscle cells yielded a chronic inflammatory response of the aortic wall, which was associated with increased fibroblasts, reinforced aortic tensile strength, and less-severe tissue destruction. Although an acute inflammatory response is detrimental in AD, smooth muscle-regulated inflammatory response seemed protective against AD.

The Expression Profile of MicroRNAs in Small and Large Abdominal Aortic Aneurysms

Background

Abdominal aortic aneurysms (AAA) are relatively frequent in elderly population, and their ruptures are related with high mortality rate. There are no actually used laboratory markers predicting the AAA development, course, and rupture. MicroRNAs are small noncoding molecules involved in posttranscriptional gene expression regulation, influencing processes on cell and tissue levels, and are actually in focus due to their potential to become diagnostic or prognostic markers in various diseases.

Methods

Tissue samples of AAA patients and healthy controls were collected, from which miRNA was isolated. Microarray including the complete panel of 2549 miRNAs was used to find expression miRNA profiles that were analysed in three subgroups: small (N = 10) and large (N = 6) aneurysms and healthy controls (N = 5). Fold changes between expression in aneurysms and normal tissue were calculated including corresponding p values, adjusted to multiple comparisons.

Results

Six miRNAs were found to be significantly dysregulated in small aneurysms (miR-7158-5p, miR-658, miR-517-5p, miR-122-5p, miR-326, and miR-3180) and 162 in large aneurysms, in comparison with the healthy control. Ten miRNAs in large aneurysms with more than two-fold significant change in expression were identified: miR-23a-3p, miR-24-3p, miR-27a-3p, miR-27b-3p, miR-30d-5p, miR-193a-3p, miR-203a-3p, miR-365a-3p, miR-4291, and miR-3663-3p and all, but the last one was downregulated in aneurysmal walls.

Conclusion

We confirmed some previously identified miRNAs (miR-23/27/24 family, miR-193a, and miR-30) as associated with AAA pathogenesis. We have found other, yet in AAA unidentified miRNAs (miR-203a, miR-3663, miR-365a, and miR-4291) for further analyses, to investigate more closely their possible role in pathogenesis of aneurysms. If their role in AAA development is proved significant in future, they can become potential markers or treatment targets.

Verification of hub genes in the expression profile of aortic dissection

Background

To assess the mRNA expression profile and explore the hub mRNAs and potential molecular mechanisms in the pathogenesis of human thoracic aortic dissection (TAD).

Methodology

mRNA microarray expression signatures of TAD tissues (n = 6) and non-TAD tissues (NT; n = 6) were analyzed by an Arraystar human mRNA microarray. Real-time PCR (qRT-PCR) was used to validate the results of the mRNA microarray. Bioinformatic tools, including Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis, were utilized. Protein-protein interaction (PPI) networks were constructed based on data from the STRING database. Molecular Complex Detection (MCODE) and cytoHubba analyses were used to predict the strongest hub gene and pathway.

Results

The top 10 hub genes were CDK1, CDC20, CCNB2, CCNB1, MAD2L1, AURKA, C3AR1, NCAPG, CXCL12 and ASPM, which were identified from the PPI network. Module analysis revealed that TAD was associated with the cell cycle, oocyte meiosis, the p53 signaling pathway, and progesterone-mediated oocyte maturation. The qRT-PCR results showed that the expression of all hub genes was significantly increased in TAD samples (p < 0.05). Immunostaining of Ki-67 and CDK1 showed a high proliferation state and high expression in TAD, respectively.

Conclusions

CDK1 could be used as a potential diagnostic biomarker and therapeutic target of TAD.

High Salt Intake Worsens Aortic Dissection in Mice: Involvement of IL (Interleukin)-17A-Dependent ECM (Extracellular Matrix) Metabolism

OBJECTIVE

Aortic dissection (AD) is a fatal disease that occurs suddenly without preceding clinical signs or symptoms. Although high salt intake is a proposed risk factor for cardiovascular diseases, the relationship between AD and high salt intake has not been clarified. We examined the effect of high-salt challenge on a mouse AD model. Approach and Results: AD was induced in male mice by continuous infusion of β-aminopropionitrile and Ang II (angiotensin II). High-salt challenge exacerbated aortic wall destruction in AD. Deletion of Il17a (IL-17KO [IL (interleukin)-17A knockout]) did not affect the AD phenotype at baseline, but it abolished the high salt-induced worsening of the aortic destruction. Unexpectedly, aortas of IL-17KO mice exhibited global changes in ECM (extracellular matrix)-related genes without alteration of proinflammatory genes, altered architecture of collagen fibers, and reduced stiffness before AD induction. The aortas of IL-17KO mice were less sensitive to AD-inducing stimuli, as shown by the induction of phenotypic modulation markers SMemb and vimentin, suggesting a reduced stress response. The aortas of IL-17KO mice had a higher population of smooth muscle cells with nuclear-localized phosphorylated Smad2, indicative of TGFβ (transforming growth factor-beta) signal activation. Consistently, pretreatment of smooth muscle cells in culture with IL-17A blunted the activation of Smad2 by TGFβ1.

CONCLUSIONS

These findings indicate that high salt intake has a worsening effect on AD in the context of high aortic wall stiffness, which is under the control of IL-17A through ECM metabolism. Therefore, salt restriction may represent a low-cost and practical way to reduce AD risk.

Lidocaine Potentiates SOCS3 to Attenuate Inflammation in Microglia and Suppress Neuropathic Pain

Lidocaine is one of the typical local anesthetics that are frequently used in the peripheral nerve blocks and pain management. Emerging evidence have shown that lidocaine may exert anti-inflammatory effect involving neuropathic pain. However, the effect and underlying mechanism of lidocaine in suppressing neuroinflammation in neuropathic pain are incompletely revealed. In this study, effects of lidocaine on the suppressors of cytokine-signaling protein 3 (SOCS3) in microglia are investigated in chronic constriction injury (CCI) rat model and lipopolysaccharide (LPS)-stimulated BV-2 cells. It was shown that intrathecal injection of lidocaine substantially alleviated CCI-induced neuropathic pain, as reflected by the decreased thermal latency and mechanical threshold. Lidocaine reduced the CCI-evoked spinal injury and cell apoptosis. CCI induced an significant increase of IBA1+ microglia accompanied by the increase of inflammatory cytokines IL-6 and IL-1β, which were suppressed after lidocaine administration. SOCS3 expression in IBA1+ microglia was notably upregulated in response to lidocaine injection, which presented in a similar pattern in LPS-activated BV-2 cells. Furthermore, lidocaine upregulated SOCS3 expression dependent of pCREB, and CREB silencing greatly discounted this effect. The intrathecal injection of lentiviral vectors LV-SOCS3 efficiently alleviated CCI-evoked neuropathic pain and reduced spinal IBA1+ microglia. SOCS3 overexpression contributed to the inhibition of neuroinflammation by decreasing the expression and activation of p38 MAPK and NF-κB stimulated by LPS. Collectively, lidocaine promoted the SOCS3 expression in microglia, in turn leading to suppression of IBA1+ microglia accumulation and p38 MAPK and NF-κB, which may expand our understanding on lidocaine in suppressing neuroinflammation and neuropathic pain.

STAT3 Activation Correlates with Adventitial Neutrophil Infiltration in Human Aortic Dissection

Objective: Aortic dissection (AD) is a fatal disease that is caused by the rapid destruction of the aortic wall. Although recent studies in animal models indicate an important relationship between inflammation and tissue destruction, activation status of inflammatory signaling and its relation to the inflammatory cell infiltration are poorly characterized in human AD.

Materials and Methods: We examined the activation of inflammatory signaling molecules NFκB and STAT3, and neutrophil infiltration in AD tissue samples that were obtained during the surgical repair within 24 h after AD onset.

Results: Activation of NFκB was observed mainly in the intima both in AD samples and in aortic samples without AD. Activation of STAT3 was observed in AD samples, but not in the aortic sample without AD. Neutrophil infiltration was observed predominantly in the adventitial layer of AD samples. Histological analysis revealed that STAT3 was activated in cells other than neutrophils. Notably, STAT3 activation and neutrophil infiltration showed positive correlation in adventitial layer of AD tissue.

Conclusion: These findings demonstrated that adventitial STAT3 activation was associated with neutrophil infiltration, suggesting their importance in AD pathogenesis.

Role of Macrophage Socs3 in the Pathogenesis of Aortic Dissection

BACKGROUND

Aortic dissection (AD) is a life-threatening medical emergency caused by the abrupt destruction of the intimomedial layer of the aortic walls. Given that previous studies have reported the involvement of proinflammatory cytokine interleukin-6 in AD pathogenesis, we investigated the role of signal transduction and activator of transcription 3 signaling, a downstream pathway of interleukin-6 in macrophages in pathogenesis of AD.

METHODS AND RESULTS

We characterized the pathological and molecular events triggered by aortic stress, which can lead to AD. Aortic stress on the suprarenal aorta because of infrarenal aorta stiffening and angiotensin II infusion for 1 week caused focal medial rupture at the branching point of the celiac trunk and superior mesenteric artery. This focal medial rupture healed in 6 weeks in wild-type (WT) mice, but progressed to AD in mice with macrophage-specific deletion of Socs3 gene (mSocs3-KO). mSocs3-KO mice showed premature activation of cell proliferation, an inflammatory response, and skewed differentiation of macrophages toward the tissue-destructive phenotype. Concomitantly, they showed aberrant phenotypic modulation of smooth muscle cells and transforming growth factor beta signaling, which are likely to participate in tissue repair. Human AD samples revealed signal transduction and activator of transcription 3 activation in adventitial macrophages adjacent to the site of tissue destruction.

CONCLUSIONS

These findings suggest that AD development is preceded by focal medial rupture, in which macrophage Socs3 maintains proper inflammatory response and differentiation of SMCs, thus promoting fibrotic healing to prevent tissue destruction and AD development. Understanding the sequence of the pathological and molecular events preceding AD development will help predict and prevent AD development and progression.