Vascular Smooth Muscle Cells in Aortic Aneurysm: From Genetics to Mechanisms

LncRNA MDRL Mitigates Atherosclerosis through miR-361/SQSTM1/NLRP3 Signaling

Objective

Long non-coding RNAs (lncRNAs) play many important roles in gene regulation and disease pathogenesis. Here, we sought to determine that mitochondrial dynamic related lncRNA (MDRL) modulates NLRP3 inflammasome activation and apoptosis of vascular smooth muscle cells (VSMCs) and protects arteries against atherosclerosis.

Methods

In vivo experiments, we applied LDLR knockout (LDLR^−/−) mice fed the high-fat diet to investigate the effects of MDRL on atherosclerosis. In vitro experiments, we applied mouse aortic smooth muscle cells to determine the mechanism of MDRL in abrogating NLRP3 inflammasome and inhibiting cell apoptosis through miR-361/sequentosome 1 (SQSTM1) by TUNEL staining, quantitative RT-PCR, western blot, microribonucleoprotein immunoprecipitation, and luciferase reporter assay.

Results

Downregulated MDRL and increased NLRP3 were observed in mouse atherosclerotic plaques, accompanied with the increase of miR-361. The results showed that MDRL overexpression significantly attenuated the burden of atherosclerotic plaque and facilitated plaque stability through inhibiting NLRP3 inflammasome activation and cell apoptosis, and vice versa. Mechanically, MDRL suppressed NLRP3 inflammasome activation and VSMC apoptosis via suppressing miR-361. Furthermore, miR-361 directly bound to the 3'UTR of SQSTM1 and inhibited its translation, subsequently activating NLRP3 inflammasome. Systematic delivery of miR-361 partly counteracted the beneficial effects of MDRL overexpression on atherosclerotic development in LDLR^−/− mice.

Conclusions

In summary, MDRL alleviates NLRP3 inflammasome activation and apoptosis in VSMCs through miR-361/SQSTM1/NLRP3 pathway during atherogenesis. These data indicate that MDRL and inhibition of miR-361 represent potential therapeutic targets in atherosclerosis-related diseases.

The multifaceted actions of the lncRNA H19 in cardiovascular biology and diseases

Cardiovascular diseases are the leading cause of death and debility worldwide. Various molecular mechanisms have been studied to better understand the development and progression of cardiovascular pathologies with hope to eradicate these diseases. With the advancement of the sequencing technology, it is revealed that the majority of our genome is non-coding. A growing body of literature demonstrates the critical role of long non-coding RNAs (lncRNAs) as epigenetic regulators of gene expression. LncRNAs can regulate cellular biological processes through various distinct molecular mechanisms. The abundance of lncRNAs in the cardiovascular system indicates their significance in cardiovascular physiology and pathology. LncRNA H19, in particular, is a highly evolutionarily conserved lncRNA that is enriched in cardiac and vascular tissue, underlining its importance in maintaining homeostasis of the cardiovascular system. In this review, we discuss the versatile function of H19 in various types of cardiovascular diseases. We highlight the current literature on H19 in the cardiovascular system and demonstrate how dysregulation of H19 induces the development of cardiovascular pathophysiology.

Translational Medicine: Towards Gene Therapy of Marfan Syndrome

Marfan syndrome (MFS) is one of the most common inherited disorders of connective tissue caused by mutations of the fibrillin-1 gene (FBN1). Vascular abnormalities, such as the enlargement of the aorta with the risk of life-threatening rupture are frequently observed. However, current treatment is limited and therapeutic options focus solely on symptomatic therapy. Gene therapy focuses on genetically modifying cells to produce a therapeutic effect and may be a promising treatment option for MFS. Here, we first provide an overview of the historical background and characterization of MFS. Subsequently, we summarise current gene therapy options and possible translational concepts for this inherited disorder that affects connective tissue.

The role of phosphoinositide 3-kinases in immune-inflammatory responses: potential therapeutic targets for abdominal aortic aneurysm

The pathogenesis of abdominal aortic aneurysm (AAA) includes inflammatory responses, matrix metalloproteinases (MMPs) degradation, VSMC apoptosis, oxidative stress, and angiogenesis, among which the inflammatory response plays a key role. At present, surgery is the only curing treatment, and no effective drug can delay AAA progression in clinical practice. Therefore, searching for a signaling pathway related to the immune-inflammatory response is an essential direction for developing drugs targeting AAA. Recent studies have confirmed that the PI3K family plays an important role in many inflammatory diseases and is involved in regulating various cellular functions, especially in the immune-inflammatory response. This review focuses on the role of each isoform of PI3K in each stage of AAA immune-inflammatory response, making available explorations for a deeper understanding of the mechanism of inflammation and immune response during the formation and development of AAA.

Large Vessel Cell Heterogeneity and Plasticity: Focus in Aortic Aneurysms

Smooth muscle cells and endothelial cells have a remarkable level of plasticity in vascular pathologies. In thoracic and abdominal aortic aneurysms, smooth muscle cells have been suggested to undergo phenotypic switching and to contribute to degradation of the aortic wall structure in response to, for example, inflammatory mediators, dysregulation of growth factor signaling or oxidative stress. Recently, endothelial-to-mesenchymal transition, and a clonal expansion of degradative smooth muscle cells and immune cells, as well as mesenchymal stem-like cells have been suggested to contribute to the progression of aortic aneurysms. What are the factors driving the aortic cell phenotype changes and how vascular flow, known to affect aortic wall structure and to be altered in aortic aneurysms, could affect aortic cell remodeling? In this review, we summarize the current literature on aortic cell heterogeneity and phenotypic switching in relation to changes in vascular flow and aortic wall structure in aortic aneurysms in clinical samples with special focus on smooth muscle and endothelial cells. The differences between thoracic and abdominal aortic aneurysms are discussed.

Development of pharmacotherapies for abdominal aortic aneurysms

The cardiovascular field is still searching for a treatment for abdominal aortic aneurysms (AAA). This inflammatory disease often goes undiagnosed until a late stage and associated rupture has a high mortality rate. No pharmacological treatment options are available. Three hallmark factors of AAA pathology include inflammation, extracellular matrix remodeling, and vascular smooth muscle dysfunction. Here we discuss drugs for AAA treatment that have been studied in clinical trials by examining the drug targets and data present for each drug's ability to regulate the aforementioned three hallmark pathways in AAA progression. Historically, drugs that were examined in interventional clinical trials for treatment of AAA were repurposed therapeutics. Novel treatments (biologics, small-molecule compounds etc.) have not been able to reach the clinic, stalling out in pre-clinical studies. Here we discuss the backgrounds of previous investigational drugs in hopes of better informing future development of potential therapeutics. Overall, the highlighted themes discussed here stress the importance of both centralized anti-inflammatory drug targets and rigor of translatability. Exceedingly few murine studies have examined an intervention-based drug treatment in halting further growth of an established AAA despite interventional treatment being the therapeutic approach taken to treat AAA in a clinical setting. Additionally, data suggest that a potentially successful drug target may be a central inflammatory biomarker. Specifically, one that can effectively modulate all three hallmark factors of AAA formation, not just inflammation. It is suggested that inhibiting PGE₂ formation with an mPGES-1 inhibitor is a leading drug target for AAA treatment to this end.

Stem Cell Based Approaches to Modulate the Matrix Milieu in Vascular Disorders

The extracellular matrix (ECM) represents a complex and dynamic framework for cells, characterized by tissue-specific biophysical, mechanical, and biochemical properties. ECM components in vascular tissues provide structural support to vascular cells and modulate their function through interaction with specific cell-surface receptors. ECM–cell interactions, together with neurotransmitters, cytokines, hormones and mechanical forces imposed by blood flow, modulate the structural organization of the vascular wall. Changes in the ECM microenvironment, as in post-injury degradation or remodeling, lead to both altered tissue function and exacerbation of vascular pathologies. Regeneration and repair of the ECM are thus critical toward reinstating vascular homeostasis. The self-renewal and transdifferentiating potential of stem cells (SCs) into other cell lineages represents a potentially useful approach in regenerative medicine, and SC-based approaches hold great promise in the development of novel therapeutics toward ECM repair. Certain adult SCs, including mesenchymal stem cells (MSCs), possess a broader plasticity and differentiation potential, and thus represent a viable option for SC-based therapeutics. However, there are significant challenges to SC therapies including, but not limited to cell processing and scaleup, quality control, phenotypic integrity in a disease milieu in vivo, and inefficient delivery to the site of tissue injury. SC-derived or -inspired strategies as a putative surrogate for conventional cell therapy are thus gaining momentum. In this article, we review current knowledge on the patho-mechanistic roles of ECM components in common vascular disorders and the prospects of developing adult SC based/inspired therapies to modulate the vascular tissue environment and reinstate vessel homeostasis in these disorders.

Disintegrin and Metalloproteinases (ADAMs [A Disintegrin and Metalloproteinase] and ADAMTSs [ADAMs With a Thrombospondin Motif]) in Aortic Aneurysm

Aortic aneurysm is a complex pathology that can be lethal if not detected in time. Although several molecular mechanisms and pathways have been identified to be involved in aortic aneurysm development and growth, the current lack of an effective pharmacological treatment highlights the need for a more thorough understanding of the factors that regulate the remodeling of the aortic wall in response to triggers that lead to aneurysm formation. This task is further complicated by the regional heterogeneity of the aorta and that thoracic and abdominal aortic aneurysm are distinct pathologies with different risk factors and distinct course of progression. ADAMs (a disintegrin and metalloproteinases) and ADAMTS (ADAMs with a thrombospondin motif) are proteinases that share similarities with other proteinases but possess unique and diverse properties that place them in a category of their own. In this review, we discuss what is known on how ADAMs and ADAMTSs are altered in abdominal aortic aneurysm and thoracic aortic aneurysm in patients, in different animal models, and their role in regulating the function of different vascular and inflammatory cell types. A full understanding of the role of ADAMs and ADAMTSs in aortic aneurysm will help reveal a more complete understanding of the underlying mechanism driving aneurysm formation, which will help towards developing an effective treatment in preventing or limiting the growth of aortic aneurysm.

Benefits of Curcumin in the Vasculature: A Therapeutic Candidate for Vascular Remodeling in Arterial Hypertension and Pulmonary Arterial Hypertension?

Growing evidence suggests that hypertension is one of the leading causes of cardiovascular morbidity and mortality since uncontrolled high blood pressure increases the risk of myocardial infarction, aortic dissection, hemorrhagic stroke, and chronic kidney disease. Impaired vascular homeostasis plays a critical role in the development of hypertension-induced vascular remodeling. Abnormal behaviors of vascular cells are not only a pathological hallmark of hypertensive vascular remodeling, but also an important pathological basis for maintaining reduced vascular compliance in hypertension. Targeting vascular remodeling represents a novel therapeutic approach in hypertension and its cardiovascular complications. Phytochemicals are emerging as candidates with therapeutic effects on numerous pathologies, including hypertension. An increasing number of studies have found that curcumin, a polyphenolic compound derived from dietary spice turmeric, holds a broad spectrum of pharmacological actions, such as antiplatelet, anticancer, anti-inflammatory, antioxidant, and antiangiogenic effects. Curcumin has been shown to prevent or treat vascular remodeling in hypertensive rodents by modulating various signaling pathways. In the present review, we attempt to focus on the current findings and molecular mechanisms of curcumin in the treatment of hypertensive vascular remodeling. In particular, adverse and inconsistent effects of curcumin, as well as some favorable pharmacokinetics or pharmacodynamics profiles in arterial hypertension will be discussed. Moreover, the recent progress in the preparation of nano-curcumins and their therapeutic potential in hypertension will be briefly recapped. The future research directions and challenges of curcumin in hypertension-related vascular remodeling are also proposed. It is foreseeable that curcumin is likely to be a therapeutic agent for hypertension and vascular remodeling going forwards.

Cysteine-rich protein 2 deficiency attenuates angiotensin II-induced abdominal aortic aneurysm formation in mice

Background

Abdominal aortic aneurysm (AAA) is a relatively common and often fatal condition. A major histopathological hallmark of AAA is the severe degeneration of aortic media with loss of vascular smooth muscle cells (VSMCs), which are the main source of extracellular matrix (ECM) proteins. VSMCs and ECM homeostasis are essential in maintaining structural integrity of the aorta. Cysteine-rich protein 2 (CRP2) is a VSMC-expressed protein; however, the role of CRP2 in AAA formation is unclear.

Methods

To investigate the function of CRP2 in AAA formation, mice deficient in Apoe (Apoe^−/−) or both CRP2 (gene name Csrp2) and Apoe (Csrp2^−/−Apoe^−/−) were subjected to an angiotensin II (Ang II) infusion model of AAA formation. Aortas were harvested at different time points and histological analysis was performed. Primary VSMCs were generated from Apoe^−/− and Csrp2^−/−Apoe^−/− mouse aortas for in vitro mechanistic studies.

Results

Loss of CRP2 attenuated Ang II-induced AAA incidence and severity, accompanied by preserved smooth muscle α-actin expression and reduced elastin degradation, matrix metalloproteinase 2 (MMP2) activity, deposition of collagen, particularly collagen III (Col III), aortic tensile strength, and blood pressure. CRP2 deficiency decreased the baseline MMP2 and Col III expression in VSMCs and mitigated Ang II-induced increases of MMP2 and Col III via blunting Erk1/2 signaling. Rescue experiments were performed by reintroducing CRP2 into Csrp2^−/−Apoe^−/− VSMCs restored Ang II-induced Erk1/2 activation, MMP2 expression and activity, and Col III levels.

Conclusions

Our results indicate that in response to Ang II stimulation, CRP2 deficiency maintains aortic VSMC density, ECM homeostasis, and structural integrity through Erk1/2–Col III and MMP2 axis and reduces AAA formation. Thus, targeting CRP2 provides a potential therapeutic strategy for AAA.

Supplementary information

The online version contains supplementary material available at 10.1186/s12929-022-00808-z.

Preservation of Smooth Muscle Cell Integrity and Function: A Target for Limiting Abdominal Aortic Aneurysm Expansion?

(1) Abdominal aortic aneurysm (AAA) is a silent, progressive disease with significant mortality from rupture. Whilst screening programmes are now able to detect this pathology early in its development, no therapeutic intervention has yet been identified to halt or retard aortic expansion. The inability to obtain aortic tissue from humans at early stages has created a necessity for laboratory models, yet it is essential to create a timeline of events from EARLY to END stage AAA progression. (2) We used a previously validated ex vivo porcine bioreactor model pre-treated with protease enzyme to create “aneurysm” tissue. Mechanical properties, histological changes in the intact vessel wall, and phenotype/function of vascular smooth muscle cells (SMC) cultured from the same vessels were investigated. (3) The principal finding was significant hyperproliferation of SMC from EARLY stage vessels, but without obvious histological or SMC aberrancies. END stage tissue exhibited histological loss of α-smooth muscle actin and elastin; mechanical impairment; and, in SMC, multiple indications of senescence. (4) Aortic SMC may offer a therapeutic target for intervention, although detailed studies incorporating intervening time points between EARLY and END stage are required. Such investigations may reveal mechanisms of SMC dysfunction in AAA development and hence a therapeutic window during which SMC differentiation could be preserved or reinstated.

Carbon monoxide releasing molecule-2 attenuates angiotensin II-induced IL-6/Jak2/Stat3-associated inflammation by inhibiting NADPH oxidase- and mitochondria-derived ROS in human aortic smooth muscle cells

Abdominal aortic aneurysm (AAA) is a common inflammatory vascular disease. Angiotensin II (Ang II) involves in AAA progression by promoting the proliferation and migration of vascular smooth muscle cells, the degradation of extracellular matrices, and the generation of ROS to lead to vascular inflammation. Carbon monoxide releasing molecule-2 (CORM-2) is known to exert anti-inflammatory and antioxidant activities. However, it remains unclear whether CORM-2 can suppress Ang II-induced vascular inflammation to prevent AAA progression. Therefore, this study aimed to investigate the vasoprotective effects of CORM-2 against Ang II-induced inflammatory responses of human aortic smooth muscle cells (HASMCs) and the underlying mechanisms of those effects. The results showed that Ang II induced inflammatory responses of HASMCs via NADPH oxidase- and mitochondria-derived ROS/NF-κB/IL-6/Jak2/Stat3 pathway which was attenuated by the pretreatment with CORM-2. Additionally, CORM-2 further exhibited anti-inflammatory activities in Ang II-stimulated HASMCs, as indicated by the reduction of monocyte adhesion to HASMCs and migration of HASMCs via the suppression of ICAM-1 and VCAM-1 as well as MMP-2 and MMP-9 levels, respectively. Moreover, Ang II-induced COX-2-mediated PGE₂ secretion was also inhibited by the pretreatment with CORM-2. Importantly, our data demonstrated that CORM-2 reversed Ang II-induced IL-6 overexpression dependent on Nrf2 activation and HO-1 expression. Taken together, the present study indicates that CORM-2-induced Nrf2/HO-1 alleviates IL-6/Jak2/Stat3-mediated inflammatory responses to Ang II by inhibiting NADPH oxidase- and mitochondria-derived ROS, suggesting that CORM-2 is a promising pharmacologic candidate to reverse the pathological changes involved in the inflammation of vessel wall for the prevention and treatment of AAA.

Update on the molecular landscape of thoracic aortic aneurysmal disease

PURPOSE OF THE REVIEW

Thoracic aortic aneurysms and dissections (TAADs) are a major health problem in the Western population. This review summarises recent discoveries in the genetic landscape of TAAD disease, discusses current challenges in clinical practice, and describes the molecular road ahead in TAAD research. Disorders, in which aneurysmal disease is not observed in the thoracic aorta, are not discussed.

RECENT FINDINGS

Current gene discovery studies have pinpointed about 40 genes associated with TAAD risk, accounting for about 30% of the patients. Importantly, novel genes, and their subsequent functional characterisation, have expanded the knowledge on disease-related pathways providing crucial information on key elements in this disease, and it pinpoints new therapeutic targets. Moreover, current molecular evidence also suggests the existence of less monogenic nature of TAAD disease, in which the presentation of a diseased patient is most likely influenced by a multitude of genetic and environmental factors.

SUMMARY CLINICAL PRACTICE/RELEVANCE

Ongoing molecular genetic research continues to expand our understanding on the pathomechanisms underlying TAAD disease in order to improve molecular diagnosis, optimise risk stratification, advance therapeutic strategies and facilitate counselling of TAAD patients and their families.

A potential role of autophagy-mediated vascular senescence in the pathophysiology of HFpEF

Heart failure with preserved ejection fraction (HFpEF) is one of the most complex and most prevalent cardiometabolic diseases in aging population. Age, obesity, diabetes, and hypertension are the main comorbidities of HFpEF. Microvascular dysfunction and vascular remodeling play a major role in its development. Among the many mechanisms involved in this process, vascular stiffening has been described as one the most prevalent during HFpEF, leading to ventricular-vascular uncoupling and mismatches in aged HFpEF patients. Aged blood vessels display an increased number of senescent endothelial cells (ECs) and vascular smooth muscle cells (VSMCs). This is consistent with the fact that EC and cardiomyocyte cell senescence has been reported during HFpEF. Autophagy plays a major role in VSMCs physiology, regulating phenotypic switch between contractile and synthetic phenotypes. It has also been described that autophagy can regulate arterial stiffening and EC and VSMC senescence. Many studies now support the notion that targeting autophagy would help with the treatment of many cardiovascular and metabolic diseases. In this review, we discuss the mechanisms involved in autophagy-mediated vascular senescence and whether this could be a driver in the development and progression of HFpEF.