Inflammatory cytokines promote mesenchymal transformation in embryonic and adult valve endothelial cells

Beyond VICs: Shedding light on the overlooked VECs in calcific aortic valve disease

Calcific aortic valve disease (CAVD) is prevalent in developed nations and has emerged as a pressing global public health concern due to population aging. The precise etiology of this disease remains uncertain, and recent research has primarily focused on examining the role of valvular interstitial cells (VICs) in the development of CAVD. The predominant treatment options currently available involve open surgery and minimally invasive interventional surgery, with no efficacious pharmacological treatment. This article seeks to provide a comprehensive understanding of valvular endothelial cells (VECs) from the aspects of valvular endothelium-derived nitric oxide (NO), valvular endothelial mechanotransduction, valvular endothelial injury, valvular endothelial-mesenchymal transition (EndMT), and valvular neovascularization, which have received less attention, and aims to establish their role and interaction with VICs in CAVD. The ultimate goal is to provide new perspectives for the investigation of non-invasive treatment options for this disease.

Multiscale computational modeling of aortic valve calcification

Calcific aortic valve disease (CAVD) is a common cardiovascular disease that affects millions of people worldwide. The disease is characterized by the formation of calcium nodules on the aortic valve leaflets, which can lead to stenosis and heart failure if left untreated. The pathogenesis of CAVD is still not well understood, but involves several signaling pathways, including the transforming growth factor beta (TGF β ) pathway. In this study, we developed a multiscale computational model for TGF β -stimulated CAVD. The model framework comprises cellular behavior dynamics, subcellular signaling pathways, and tissue-level diffusion fields of pertinent chemical species, where information is shared among different scales. Processes such as endothelial to mesenchymal transition (EndMT), fibrosis, and calcification are incorporated. The results indicate that the majority of myofibroblasts and osteoblast-like cells ultimately die due to lack of nutrients as they become trapped in areas with higher levels of fibrosis or calcification, and they subsequently act as sources for calcium nodules, which contribute to a polydispersed nodule size distribution. Additionally, fibrosis and calcification processes occur more frequently in regions closer to the endothelial layer where the cell activity is higher. Our results provide insights into the mechanisms of CAVD and TGF β signaling and could aid in the development of novel therapeutic approaches for CAVD and other related diseases such as cancer. More broadly, this type of modeling framework can pave the way for unraveling the complexity of biological systems by incorporating several signaling pathways in subcellular models to simulate tissue remodeling in diseases involving cellular mechanobiology.

Endothelial to mesenchymal transition: at the axis of cardiovascular health and disease

Endothelial cells (ECs) line the luminal surface of blood vessels and play a major role in vascular (patho)-physiology by acting as a barrier, sensing circulating factors and intrinsic/extrinsic signals. ECs have the capacity to undergo endothelial-to-mesenchymal transition (EndMT), a complex differentiation process with key roles both during embryonic development and in adulthood. EndMT can contribute to EC activation and dysfunctional alterations associated with maladaptive tissue responses in human disease. During EndMT, ECs progressively undergo changes leading to expression of mesenchymal markers while repressing EC lineage-specific traits. This phenotypic and functional switch is considered to largely exist in a continuum, being characterized by a gradation of transitioning stages. In this report, we discuss process plasticity and potential reversibility and the hypothesis that different EndMT-derived cell populations may play a different role in disease progression or resolution. In addition, we review advancements in the EndMT field, current technical challenges, as well as therapeutic options and opportunities in the context of cardiovascular biology.

Forsythoside B Mitigates Monocrotaline-Induced Pulmonary Arterial Hypertension via Blocking the NF-κB Signaling Pathway to Attenuate Vascular Remodeling

Purpose

Pulmonary arterial hypertension (PAH) is a devastating disease with little effective treatment. The proliferation of pulmonary artery smooth muscle cells (PASMCs) induced by the nuclear factor-κB (NF-κB) signaling activation plays a pivotal role in the pathogenesis of PAH. Forsythoside B (FTS•B) possesses inhibitory effect on NF-κB signaling pathway. The present study aims to explore the effects and mechanisms of FTS•B in PAH.

Methods

Sprague-Dawley rats received monocrotaline (MCT) intraperitoneal injection to establish PAH model, and FTS•B was co-treated after MCT injection. Right ventricular hypertrophy and pulmonary artery pressure were measured by echocardiography and right heart catheterization, respectively. Histological alterations were detected by H&E staining and immunohistochemistry. FTS•B's role in PASMC proliferation and migration were evaluated by CCK-8 and wound healing assay. To investigate the underlying mechanisms, Western blotting, immunofluorescence staining and ELISA were conducted. The NF-κB activator PMA was used to investigate the role of NF-κB in FTS•B's protective effects against PAH.

Results

FTS•B markedly alleviated MCT-induced vascular remodeling and pulmonary artery pressure, and improved right ventricular hypertrophy and survival. FTS•B also reversed PDGF-BB-induced PASMC proliferation and migration, decreased PCNA and CyclinD1 expression in vitro. The elevated levels of IL-1β and IL-6 caused by MCT were decreased by FTS•B. Mechanistically, MCT-triggered phosphorylation of p65, IκBα, IKKα and IKKβ was blunted by FTS•B. FTS•B also reversed MCT-induced nuclear translocation of p65. However, all these protective effects were blocked by PMA-mediated NF-κB activation.

Conclusion

FTS•B effectively attenuates PAH by suppressing the NF-κB signaling pathway to attenuate vascular remodeling. FTS•B might be a promising drug candidate with clinical translational potential for the treatment of PAH.

Indoxyl Sulfate-Induced Valve Endothelial Cell Endothelial-to-Mesenchymal Transition and Calcification in an Integrin-Linked Kinase-Dependent Manner

Calcific Aortic Valve Disease (CAVD) is a significant concern for cardiovascular health and is closely associated with chronic kidney disease (CKD). Aortic valve endothelial cells (VECs) play a significant role in the onset and progression of CAVD. Previous research has suggested that uremic toxins, particularly indoxyl sulfate (IS), induce vascular calcification and endothelial dysfunction, but the effect of IS on valve endothelial cells (VECs) and its contribution to CAVD is unclear. Our results show that IS reduced human VEC viability and increased pro-calcific markers RUNX2 and alkaline phosphatase (ALP) expression. Additionally, IS-exposed VECs cultured in pro-osteogenic media showed increased calcification. Mechanistically, IS induced endothelial-to-mesenchymal transition (EndMT), evidenced by the loss of endothelial markers and increased expression of mesenchymal markers. IS triggered VEC inflammation, as revealed by NF-kB activation, and decreased integrin-linked kinase (ILK) expression. ILK overexpression reversed the loss of endothelial phenotype and RUNX2, emphasizing its relevance in the pathogenesis of CAVD in CKD. Conversely, a lower dose of IS intensified some of the effects in EndMT caused by silencing ILK. These findings imply that IS affects valve endothelium directly, contributing to CAVD by inducing EndMT and calcification, with ILK acting as a crucial modulator.

Cellular Transdifferentiation: A Crucial Mechanism of Fibrosis in Systemic Sclerosis

Systemic Sclerosis (SSc) is a systemic autoimmune disease of unknown etiology with a highly complex pathogenesis that despite extensive investigation is not completely understood. The clinical and pathologic manifestations of the disease result from three distinct processes: 1) Severe and frequently progressive tissue fibrosis causing exaggerated and deleterious accumulation of interstitial collagens and other extracellular matrix molecules in the skin and various internal organs; 2) extensive fibroproliferative vascular lesions affecting small arteries and arterioles causing tissue ischemic alterations; and 3) cellular and humoral immunity abnormalities with the production of numerous autoantibodies, some with very high specificity for SSc. The fibrotic process in SSc is one of the main causes of disability and high mortality of the disease. Owing to its essentially universal presence and the severity of its clinical effects, the mechanisms involved in the development and progression of tissue fibrosis have been extensively investigated, however, despite intensive investigation, the precise molecular mechanisms have not been fully elucidated. Several recent studies have suggested that cellular transdifferentiation resulting in the phenotypic conversion of various cell types into activated myofibroblasts may be one important mechanism. Here, we review the potential role that cellular transdifferentiation may play in the development of severe and often progressive tissue fibrosis in SSc.

Palmdelphin Deficiency Evokes NF-κB Signaling in Valvular Endothelial Cells and Aggravates Aortic Valvular Remodeling

Palmd-deficient mice of advanced age manifest increased aortic valve peak velocity, thickened aortic valve leaflets, and excessive extracellular matrix deposition, which are key features of calcific aortic valve disease. PALMD is predominantly expressed in endothelial cells of aortic valves, and PALMD-silenced valvular endothelial cells are prone to oscillatory shear stress-induced endothelial-to-mesenchymal transition. Mechanistically, PALMD is associated with TNFAIP3 interaction protein 1, a binding protein of TNFAIP3 and IKBKG in NF-κB signaling. Loss of PALMD impairs TNFAIP3-dependent deubiquitinating activity and promotes the ubiquitination of IKBKG and subsequent NF-κB activation. Adeno-associated virus-mediated PALMD overexpression ameliorates aortic valvular remodeling in mice with calcific aortic valve disease, indicating protection.

Vascular organoids: unveiling advantages, applications, challenges, and disease modelling strategies

Understanding mechanisms and manifestations of cardiovascular risk factors, including diabetes, on vascular cells such as endothelial cells, pericytes, and vascular smooth muscle cells, remains elusive partly due to the lack of appropriate disease models. Therefore, here we explore different aspects for the development of advanced 3D in vitro disease models that recapitulate human blood vessel complications using patient-derived induced pluripotent stem cells, which retain the epigenetic, transcriptomic, and metabolic memory of their patient-of-origin. In this review, we highlight the superiority of 3D blood vessel organoids over conventional 2D cell culture systems for vascular research. We outline the key benefits of vascular organoids in both health and disease contexts and discuss the current challenges associated with organoid technology, providing potential solutions. Furthermore, we discuss the diverse applications of vascular organoids and emphasize the importance of incorporating all relevant cellular components in a 3D model to accurately recapitulate vascular pathophysiology. As a specific example, we present a comprehensive overview of diabetic vasculopathy, demonstrating how the interplay of different vascular cell types is critical for the successful modelling of complex disease processes in vitro. Finally, we propose a strategy for creating an organ-specific diabetic vasculopathy model, serving as a valuable template for modelling other types of vascular complications in cardiovascular diseases by incorporating disease-specific stressors and organotypic modifications.

Obesity accelerates endothelial-to-mesenchymal transition in adipose tissues of mice and humans

Introduction

Vascular dysfunction and chronic inflammation are characteristics of obesity-induced adipose tissue dysfunction. Proinflammatory cytokines can drive an endothelial-to-mesenchymal transition (EndoMT), where endothelial cells undergo a phenotypic switch to mesenchymal-like cells that are pro-inflammatory and pro-fibrotic. In this study, we sought to determine whether obesity can promote EndoMT in adipose tissue.

Methods

Mice in which endothelial cells are lineage-traced with eYFP were fed a high-fat/high-sucrose (HF/HS) or Control diet for 13, 26, and 52 weeks, and EndoMT was assessed in adipose tissue depots as percentage of CD45-CD31-Acta2+ mesenchymal-like cells that were eYFP +. EndoMT was also assessed in human adipose endothelial cells through cell culture assays and by the analysis of single cell RNA sequencing datasets obtained from the visceral adipose tissues of obese individuals.

Results

Quantification by flow cytometry showed that mice fed a HF/HS diet display a time-dependent increase in EndoMT over Control diet in subcutaneous adipose tissue (+3.0%, +2.6-fold at 13 weeks; +10.6%, +3.2-fold at 26 weeks; +11.8%, +2.9-fold at 52 weeks) and visceral adipose tissue (+5.5%, +2.3-fold at 13 weeks; +20.7%, +4.3-fold at 26 weeks; +25.7%, +4.8-fold at 52 weeks). Transcriptomic analysis revealed that EndoMT cells in visceral adipose tissue have enriched expression of genes associated with inflammatory and TGFβ signaling pathways. Human adipose-derived microvascular endothelial cells cultured with TGF-β1, IFN-γ, and TNF-α exhibited a similar upregulation of EndoMT markers and induction of inflammatory response pathways. Analysis of single cell RNA sequencing datasets from visceral adipose tissue of obese patients revealed a nascent EndoMT sub-cluster of endothelial cells with reduced PECAM1 and increased ACTA2 expression, which was also enriched for inflammatory signaling genes and other genes associated with EndoMT.

Discussion

These experimental and clinical findings show that chronic obesity can accelerate EndoMT in adipose tissue. We speculate that EndoMT is a feature of adipose tissue dysfunction that contributes to local inflammation and the systemic metabolic effects of obesity..

GDF15 affects venous thrombosis by promoting EndMT through smad2/p-smad2 pathway

BACKGROUND

Endothelial-to-mesenchymal transition (EndMT) is a pathophysiological change in the vascular endothelium commonly seen in the cardiovascular system. Elevated serum Growth differiention factor 15 (GDF15) has been reported in VTE patients, but the relationship and mechanism between GDF15, EndMT and VTE are still unclear.

METHODS

We performed a retrospective clinical study, and human serum GDF15 expression levels were detected. The mouse DVT model was established through subtotal ligation of the mouse inferior vena cava, and then we detected intimal changes and thrombi in the stenotic inferior vena cava by haematoxylin-eosin (HE) staining, Masson staining, and Sirius Red staining. The expression levels of GDF15 and SM22 were detected by immunohistochemistry and RT‒qPCR. Serum samples of mice were collected, and the expression level of GDF15 in serum was detected. Human umbilical vein endothelial cells (HUVECs) were stimulated with a cytokine mixture (TGF-β1 + TNF-α + IL-1β). The role and mechanism of GDF15 in EndMT and VTE were detected in HUVECs and in a DVT mice model.

RESULTS

We found that serum GDF15 levels in both VTE patients and mouse DVT models were higher than those in the control group. EndMT was increased in the stenotic vascular tissue of mice. Further experiments showed that GDF15 could promote the EndMT of HUVECs and reduce their anticoagulation and antifibrinolytic ability through the smad2/p-smad2/snail pathway. Inhibition of mature GDF15 release can significantly reduce venous thrombotic fibre deposition in mice.

CONCLUSIONS

GDF15 positively promotes EndMT through activation of the Smad2/psmad2/snail pathway, and inhibition of GDF15 expression can alleviate the EndMT process, further improving the coagulation and fibrinolytic function of endothelial cells and thus reducing the local fibre deposition of venous thrombi.

Embedding and Backscattered Scanning Electron Microscopy (EM-BSEM) Is Preferential over Immunophenotyping in Relation to Bioprosthetic Heart Valves

Hitherto, calcified aortic valves (AVs) and failing bioprosthetic heart valves (BHVs) have been investigated by similar approaches, mostly limited to various immunostaining techniques. Having employed multiple immunostaining combinations, we demonstrated that AVs retain a well-defined cellular hierarchy even at severe stenosis, whilst BHVs were notable for the stochastic degradation of the extracellular matrix (ECM) and aggressive infiltration by ECM-digesting macrophages. Leukocytes (CD45+) comprised ≤10% cells in the AVs but were the predominant cell lineage in BHVs (≥80% cells). Albeit cells with uncertain immunophenotype were rarely encountered in the AVs (≤5% cells), they were commonly found in BHVs (≥80% cells). Whilst cell conversions in the AVs were limited to the endothelial-to-mesenchymal transition (represented by CD31+α-SMA+ cells) and the formation of endothelial-like (CD31+CD68+) cells at the AV surface, BHVs harboured numerous macrophages with a transitional phenotype, mostly CD45+CD31+, CD45+α-SMA+, and CD68+α-SMA+. In contrast to immunostaining, which was unable to predict cell function in the BHVs, our whole-specimen, nondestructive electron microscopy approach (EM-BSEM) was able to distinguish between quiescent and matrix-degrading macrophages, foam cells, and multinucleated giant cells to conduct the ultrastructural analysis of organelles and the ECM, and to preserve tissue integrity. Hence, we suggest EM-BSEM as a technique of choice for studying the cellular landscape of BHVs.

CXCL8 Promotes Endothelial-to-Mesenchymal Transition of Endothelial Cells and Protects Cells from Erastin-Induced Ferroptosis via CXCR2-Mediated Activation of the NF-κB Signaling Pathway

CXCL8-CXCR1/CXCR2 signaling pathways might form complex crosstalk among different cell types within the ovarian tumor microenvironment, thereby modulating the behaviors of different cells. This study aimed to investigate the expression pattern of CXCL8 in the ovarian tumor microenvironment and its impact on both endothelial-to-mesenchymal transition (EndMT) and ferroptosis of endothelial cells. The human monocytic cell line THP-1 and the human umbilical vein endothelial cell line PUMC-HUVEC-T1 were used to conduct in vitro studies. Erastin was used to induce ferroptosis. Results showed that tumor-associated macrophages are the major source of CXCL8 in the tumor microenvironment. CXCL8 treatment promoted the nucleus entrance of NF-κB p65 and p65 phosphorylation via CXCR2 in endothelial cells, suggesting activated NF-κB signaling. Via the NF-κB signaling pathway, CXCL8 enhanced TGF-β1-induced EndMT of PUMC-HUVEC-T1 cells and elevated their expression of SLC7A11 and GPX4. These trends were drastically weakened in groups with CXCR2 knockdown or SB225002 treatment. TPCA-1 reversed CXCL8-induced upregulation of SLC7A11 and GPX4. CXCL8 protected endothelial cells from erastin-induced ferroptosis. However, these protective effects were largely canceled when CXCR2 was knocked down. In summary, CXCL8 can activate the NF-κB signaling pathway in endothelial cells in a CXCR2-dependent manner. The CXCL8-CXCR2/NF-κB axis can enhance EndMT and activate SLC7A11 and GPX4 expression, protecting endothelial cells from ferroptosis.

Epithelial-Mesenchymal Plasticity and Endothelial-Mesenchymal Transition in Cutaneous Wound Healing

Epithelial and endothelial cells possess the inherent plasticity to undergo morphological, cellular, and molecular changes leading to their resemblance of mesenchymal cells. A prevailing notion has been that cutaneous wound reepithelialization involves partial epithelial-to-mesenchymal transition (EMT) of wound-edge epidermal cells to enable their transition from a stationary state to a migratory state. In this review, we reflect on past findings that led to this notion and discuss recent studies that suggest a refined view, focusing predominantly on in vivo results using mammalian excisional wound models. We highlight the concept of epithelial-mesenchymal plasticity (EMP), which emphasizes a reversible conversion of epithelial cells across multiple intermediate states within the epithelial-mesenchymal spectrum, and discuss the critical importance of restricting EMT for effective wound reepithelialization. We also outline the current state of knowledge on EMP in pathological wound healing, and on endothelial-to-mesenchymal transition (EndMT), a process similar to EMT, as a possible mechanism contributing to wound fibrosis and scar formation. Harnessing epithelial/endothelial-mesenchymal plasticity may unravel opportunities for developing new therapeutics to treat human wound healing pathologies.

Higher Improvement of Cardiac Function Following Myocardial Infarction using Menstrual Blood Stromal/Stem Cells (MenSCs) Suspended in Conditioned Medium versus Conditioned Medium Alone in Rat Model

Background

To evaluate the efficiency of Menstrual blood Stromal/Stem Cells (MenSCs) administration in Myocardial Infarction (MI), the effects of MenSCs and their derived conditioned Medium (CM) on cardiac function in MI rat model was assessed.

Methods

Animals were divided into four groups including sham group, MI group, MenSCs derived CM group (CM group), and MenSCs suspended in CM (MenSCs+CM) group. The injection of different groups was carried out 30 min after ligation of left anterior descending coronary artery into the infarct border zone.

Results

The results showed a significant reduction in scar size after injection of MenSCs+CM compared to MI group. Ejection fraction and fractional shortening of MenSCs+CM group were higher than CM and MI group at day 28. Administration of MenSCs+CM led to much more survival of cardiomyocytes, and prevention of meta-plastic development. Moreover, human mitochondrial transfer from MenSCs to cardiomyocytes was seen in group treated by MenSCs+CM. Indeed, MenSCs+CM treatment evoked nuclear factor-κB (NF-κB) down-regulation more than other treatments.

Conclusion

MenSCs+CM treatment could significantly ameliorate cardiac function by different mechanisms including inhibition of cartilaginous metaplasia, inhibition of NF-κB and mitochondrial transfer.

Human and porcine aortic valve endothelial and interstitial cell isolation and characterization

Background

Calcific aortic valve stenosis (AVS) is defined by pathological changes in the aortic valve (AV) and their predominant cell types: valvular interstitial (VICs) and endothelial cells (VECs). Understanding the cellular and molecular mechanisms of this disease is a prerequisite to identify potential pharmacological treatment strategies. In this study, we present a unique aortic valve cell isolation technique to acquire specific human and porcine cell populations and compared VICs and VECs of these species with each other for the first time.

Methods

AV cells were isolated from tissue obtained from human patients undergoing surgical aortic valve replacement (SAVR) or from porcine hearts. Functional analysis and in vitro experiments revealed that endothelial-to-mesenchymal transition (EndMT) can be induced in hVECs, leading to a significant increase in mesenchymal markers. In vitro calcification experiments of VICs demonstrated pronounced expression of calcification markers and visible calcific deposits in Alizarin Red staining in both species after incubation with pro-calcific media.

Results

Cells isolated from patient-derived AVs showed mesenchymal and endothelial-specific gene signatures (VIC and VEC, respectively). For instance, von Willebrand factor (vWF) and platelet endothelial adhesion molecule-1 (PECAM1) were upregulated in VECs, while the myofibroblastic markers alpha-smooth muscle actin (α-SMA) and vimentin (VIM) were downregulated in VECs compared to VICs. Analysis of cell function by migration revealed that VECs are more migratory than VICs. Induction of EndMT in vitro in VECs displayed increased expression of EndMT markers and decreased expression of endothelial markers, confirming their mesenchymal transdifferentiation ability. In vitro calcification of VICs revealed upregulation of alkaline phosphatase (ALPL), a hallmark of calcification. In addition, other calcification-related genes such as osteocalcin (BGLAP) and runt-related factor 2 (RUNX2) were upregulated. Alizarin red staining of calcified cells provided a further layer of confirmation that the isolated cells were VICs with osteoblastic differentiation capacity.

Conclusion

This study aims to take a first step towards standardizing a reproducible isolation technique for specific human and porcine VEC and VIC populations. A comparison of human and porcine aortic valve cells demonstrated that porcine cells may serve as an alternative cellular model system in settings where human tissue is difficult to obtain.

Molecular mechanisms of endothelial remodeling under doxorubicin treatment

Doxorubicin (DOX) is an effective antineoplastic agent used to treat various types of cancers. However, its use is limited by the development of cardiotoxicity, which may result in heart failure. The exact mechanisms underlying DOX-induced cardiotoxicity are not fully understood, but recent studies have shown that endothelial-mesenchymal transition (EndMT) and endothelial damage play a crucial role in this process. EndMT is a biological process in which endothelial cells lose their characteristics and transform into mesenchymal cells, which have a fibroblast-like phenotype. This process has been shown to contribute to tissue fibrosis and remodeling in various diseases, including cancer and cardiovascular diseases. DOX-induced cardiotoxicity has been demonstrated to increase the expression of EndMT markers, suggesting that EndMT may play a critical role in the development of this condition. Furthermore, DOX-induced cardiotoxicity has been shown to cause endothelial damage, leading to the disruption of the endothelial barrier function and increased vascular permeability. This can result in the leakage of plasma proteins, leading to tissue edema and inflammation. Moreover, DOX can impair the production of nitric oxide, endothelin-1, neuregulin, thrombomodulin, thromboxane B2 etc. by endothelial cells, leading to vasoconstriction, thrombosis and further impairing cardiac function. In this regard, this review is devoted to the generalization and structuring of information about the known molecular mechanisms of endothelial remodeling under the action of DOX.

Oxidative stress and valvular endothelial cells in aortic valve calcification

Calcified aortic valve disease (CAVD) is a common cardiovascular disease in elderly individuals. Although it was previously considered a degenerative disease, it is, in fact, a progressive disease involving multiple mechanisms. Aortic valve endothelial cells, which cover the outermost layer of the aortic valve and are directly exposed to various pathogenic factors, play a significant role in the onset and progression of CAVD. Hemodynamic changes can directly damage the structure and function of valvular endothelial cells (VECs). This leads to inflammatory infiltration and oxidative stress, which promote the progression of CAVD. VECs can regulate the pathological differentiation of valvular interstitial cells (VICs) through NO and thus affect the process of CAVD. Under the influence of pathological factors, VECs can also be transformed into VICs through EndMT, and then the pathological differentiation of VICs eventually leads to the formation of calcification. This review discusses the role of VECs, especially the role of oxidative stress in VECs, in the process of aortic valve calcification.

Phytochemicals targeting lncRNAs: A novel direction for neuroprotection in neurological disorders

Neurological disorders with various etiologies impacting the nervous system are prevalent in clinical practice. Long non-coding RNA (lncRNA) molecules are functional RNA molecules exceeding 200 nucleotides in length that do not encode proteins, but participate in essential activities. Research indicates that lncRNAs may contribute to the pathogenesis of neurological disorders, and may be potential targets for their treatment. Phytochemicals in traditional Chinese herbal medicine (CHM) have been found to exert neuroprotective effects by targeting lncRNAs and regulating gene expression and various signaling pathways. We aim to establish the development status and neuroprotective mechanism of phytochemicals that target lncRNAs through a thorough literature review. A total of 369 articles were retrieved through manual and electronic searches of PubMed, Web of Science, Scopus and CNKI databases from inception to September 2022. The search utilized combinations of natural products, lncRNAs, neurological disorders, and neuroprotective effects as keywords. The included studies, a total of 31 preclinical trials, were critically reviewed to present the current situation and the progress in phytochemical-targeted lncRNAs in neuroprotection. Phytochemicals have demonstrated neuroprotective effects in preclinical studies of various neurological disorders by regulating lncRNAs. These disorders include arteriosclerotic ischemia-reperfusion injury, ischemic/hemorrhagic stroke, Alzheimer's disease, Parkinson's disease, glioma, peripheral nerve injury, post-stroke depression, and depression. Several phytochemicals exert neuroprotective roles through mechanisms such as anti-inflammatory, antioxidant, anti-apoptosis, autophagy regulation, and antagonism of Aβ-induced neurotoxicity. Some phytochemicals targeted lncRNAs and served a neuroprotective role by regulating microRNA and mRNA expression. The emergence of lncRNAs as pathological regulators provides a novel direction for the study of phytochemicals in CHM. Elucidating the mechanism of phytochemicals regulating lncRNAs will help to identify new therapeutic targets and promote their application in precision medicine.

Calcific aortic valve disease: mechanisms, prevention and treatment

Calcific aortic valve disease (CAVD) is the most common disorder affecting heart valves and is characterized by thickening, fibrosis and mineralization of the aortic valve leaflets. Analyses of surgically explanted aortic valve leaflets have shown that dystrophic mineralization and osteogenic transition of valve interstitial cells co-occur with neovascularization, microhaemorrhage and abnormal production of extracellular matrix. Age and congenital bicuspid aortic valve morphology are important and unalterable risk factors for CAVD, whereas additional risk is conferred by elevated blood pressure and plasma lipoprotein(a) levels and the presence of obesity and diabetes mellitus, which are modifiable factors. Genetic and molecular studies have identified that the NOTCH, WNT-β-catenin and myocardin signalling pathways are involved in the control and commitment of valvular cells to a fibrocalcific lineage. Complex interactions between valve endothelial and interstitial cells and immune cells promote the remodelling of aortic valve leaflets and the development of CAVD. Although no medical therapy is effective for reducing or preventing the progression of CAVD, studies have started to identify actionable targets.

Regulation of Inflammation-Mediated Endothelial to Mesenchymal Transition with Echinochrome a for Improving Myocardial Dysfunction

Endothelial-mesenchymal transition (EndMT) is a process by which endothelial cells (ECs) transition into mesenchymal cells (e.g., myofibroblasts and smooth muscle cells) and induce fibrosis of cells/tissues, due to ischemic conditions in the heart. Previously, we reported that echinochrome A (EchA) derived from sea urchin shells can modulate cardiovascular disease by promoting anti-inflammatory and antioxidant activity; however, the mechanism underlying these effects was unclear. We investigated the role of EchA in the EndMT process by treating human umbilical vein ECs (HUVECs) with TGF-β2 and IL-1β, and confirmed the regulation of cell migration, inflammatory, oxidative responses and mitochondrial dysfunction. Moreover, we developed an EndMT-induced myocardial infarction (MI) model to investigate the effect of EchA in vivo. After EchA was administered once a day for a total of 3 days, the histological and functional improvement of the myocardium was investigated to confirm the control of the EndMT. We concluded that EchA negatively regulates early or inflammation-related EndMT and reduces the myofibroblast proportion and fibrosis area, meaning that it may be a potential therapy for cardiac regeneration or cardioprotection from scar formation and cardiac fibrosis due to tissue granulation. Our findings encourage the study of marine bioactive compounds for the discovery of new therapeutics for recovering ischemic cardiac injuries.

Vascular dysfunction in COVID-19 patients: update on SARS-CoV-2 infection of endothelial cells and the role of long non-coding RNAs

Although COVID-19 is primarily a respiratory disease, it may affect also the cardiovascular system. COVID-19 patients with cardiovascular disorder (CVD) develop a more severe disease course with a significantly higher mortality rate than non-CVD patients. A common denominator of CVD is the dysfunction of endothelial cells (ECs), increased vascular permeability, endothelial-to-mesenchymal transition, coagulation, and inflammation. It has been assumed that clinical complications in COVID-19 patients suffering from CVD are caused by SARS-CoV-2 infection of ECs through the angiotensin-converting enzyme 2 (ACE2) receptor and the cellular transmembrane protease serine 2 (TMPRSS2) and the consequent dysfunction of the infected vascular cells. Meanwhile, other factors associated with SARS-CoV-2 entry into the host cells have been described, including disintegrin and metalloproteinase domain-containing protein 17 (ADAM17), the C-type lectin CD209L or heparan sulfate proteoglycans (HSPG). Here, we discuss the current data about the putative entry of SARS-CoV-2 into endothelial and smooth muscle cells. Furthermore, we highlight the potential role of long non-coding RNAs (lncRNAs) affecting vascular permeability in CVD, a process that might exacerbate disease in COVID-19 patients.

Cellular Senescence, Aging and Non-Aging Processes in Calcified Aortic Valve Stenosis: From Bench-Side to Bedside

Aortic valve stenosis (AS) is the most common valvular heart disease. The incidence of AS increases with age, however, a significant proportion of elderly people have no significant AS, indicating that both aging and nonaging pathways are involved in the pathomechanism of AS. Age-related and stress-induced cellular senescence accompanied by further active processes represent the key elements of AS pathomechanism. The early stage of aortic valve degeneration involves dysfunction and disruption of the valvular endothelium due to cellular senescence and mechanical stress on blood flow. These cells are replaced by circulating progenitor cells, but in an age-dependent decelerating manner. When endothelial denudation is no longer replaced by progenitor cells, the path opens for focal lipid deposition, initiating subsequent oxidation, inflammation and micromineralisation. Later stages of AS feature a complex active process with extracellular matrix remodeling, fibrosis and calcification. Echocardiography is the gold standard method for diagnosing aortic valve disease, although computed tomography and cardiac magnetic resonance are useful additional imaging methods. To date, no medical treatment has been proven to halt the progression of AS. Elucidation of differences and similarities between vascular and valvular calcification pathomechanisms may help to find effective medical therapy and reduce the increasing health burden of the disease.

IL6 gene polymorphism association with calcific aortic valve stenosis and influence on serum levels of interleukin-6

Aortic valve stenosis is the most frequent valve disease in developed countries and its prevalence will increase with population aging. There is still no pharmaceutical treatment nor biomarker to determine the susceptibility to develop aortic stenosis. Therefore, we analyzed the association of polymorphisms in risk loci with calcific aortic stenosis. Patients with aortic valve disease were genotyped for PALMD rs6702619, LPA rs10455872, and IL6 rs1800795 polymorphisms and circulating levels of interleukin-6 (IL-6) were measured. Calcium content of leaflets obtained in valve replacement surgeries was determined by micro-computed tomography. In the genotyping of 578 individuals, we found significant association between PALMD and IL6 polymorphisms and aortic stenosis in patients with tricuspid aortic valve, independently of other potentially confounding variables such as age and dyslipidemia. There was no association of these polymorphisms with valve calcium content, but this value correlated with the mean aortic pressure gradient (r = 0.44; P < 0.001). The CC genotype of IL6 polymorphism was associated with higher levels of serum IL-6 compared to other genotypes (23.5 vs. 10.5 pg/ml, respectively; P = 0.029). Therefore, patients carrying the CC genotype of IL6 rs1800795 polymorphism present higher levels of circulating IL-6 and this could contribute to the severity of the aortic valve stenosis. Our results agree with the identification of IL6 as a locus risk for stenosis and also with the intervention of this cytokine in aortic valve calcification. A more exhaustive follow-up of those patients carrying risk genotypes is therefore recommended.

Loss of α7nAChR enhances endothelial-to-mesenchymal transition after myocardial infarction via NF-κB activation

The myocardial fibrosis in response to myocardial infarction (MI) is closely related to the dysbalance of endothelial-to-mesenchymal transition (EndMT). Although numerous reports indicate that α7 nicotinic acetylcholine receptor (α7nAChR) activates the cholinergic anti-inflammatory pathway (CAP) to regulate the magnitude of inflammatory responses, the role of α7nAChR in myocardial fibrosis, as well as the underlying mechanisms, have not been elucidated. In this study, we evaluated cardiac function, fibrosis, and EndMT signaling using a mouse model of MI and interleukin (IL)-1β-induced human cardiac microvascular endothelial cells (HCMECs). In vivo, α7nAChR deletion increased cardiac dysfunction, exacerbated the cardiac inflammatory response, and NF-κB activation, and enhanced EndMT, as shown by higher expression levels of fibroblast markers (FSP-1, α-SMA, collagen I, Snail) and decreased levels of the FGFR1, glucocorticoid receptor (GR) and endothelial marker (CD31) compared to wild-type mice. In vitro, the pharmacological activation of α7nAChR with PNU282987 significantly inhibited IL-1β-induced EndMT, as shown by a reduced transition to the fibroblast-like phenotype and the expression of fibrotic markers. Moreover, the IL-1β-mediated activation of NF-κB pathway was suppressed by PNU282987. This anti-EndMT effect of α7nAChR was associated with regulation of Snail. Furthermore, Western blot analysis further revealed that the GR antagonist RU38486 could partially counteract the effect of PNU282987 on NF-κB expression. In conclusion, our results show that α7nAChR is involved in cardiac fibrosis by inhibiting EndMT, providing a novel approach to the treatment of MI.

Integrin-Linked Kinase Expression in Human Valve Endothelial Cells Plays a Protective Role in Calcific Aortic Valve Disease

Calcific aortic valve disease (CAVD) is highly prevalent during aging. CAVD initiates with endothelial dysfunction, leading to lipid accumulation, inflammation, and osteogenic transformation. Integrin-linked kinase (ILK) participates in the progression of cardiovascular diseases, such as endothelial dysfunction and atherosclerosis. However, ILK role in CAVD is unknown. First, we determined that ILK expression is downregulated in aortic valves from patients with CAVD compared to non-CAVD, especially at the valve endothelium, and negatively correlated with calcification markers. Silencing ILK expression in human valve endothelial cells (siILK-hVECs) induced endothelial-to-mesenchymal transition (EndMT) and promoted a switch to an osteoblastic phenotype; SiILK-hVECs expressed increased RUNX2 and developed calcified nodules. siILK-hVECs exhibited decreased NO production and increased nitrosative stress, suggesting valvular endothelial dysfunction. NO treatment of siILK-hVECs prevented VEC transdifferentiation, while treatment with an eNOS inhibitor mimicked ILK-silencing induction of EndMT. Accordingly, NO treatment inhibited VEC calcification. Mechanistically, siILK-hVECs showed increased Smad2 phosphorylation, suggesting a TGF-β-dependent mechanism, and NO treatment decreased Smad2 activation and RUNX2. Experiments performed in eNOS KO mice confirmed the involvement of the ILK-eNOS signaling pathway in valve calcification, since aortic valves from these animals showed decreased ILK expression, increased RUNX2, and calcification. Our study demonstrated that ILK endothelial expression participates in human CAVD development by preventing endothelial osteogenic transformation.

Dihydromyricetin ameliorates osteogenic differentiation of human aortic valve interstitial cells by targeting c-KIT/interleukin-6 signaling pathway

Aims: Calcific aortic valve disease (CAVD) is a chronic cardiovascular disease with high morbidity that lacks effective pharmacotherapeutics. As a natural flavonoid extracted from Ampelopsis grossedentata, dihydromyricetin (DHM) has been shown to be effective in protecting against atherosclerosis; yet, the therapeutic role of DHM in CAVD remains poorly understood. Herein, we aimed to clarify the therapeutic implications of DHM in CAVD and the underlying molecular mechanisms in human valvular interstitial cells (hVICs).

Methods and Results: The protein levels of two known osteogenesis-specific genes (alkaline phosphatase, ALP; runt-related transcription factor 2, Runx2) and calcified nodule formation in hVICs were detected by Western blot and Alizarin Red staining, respectively. The results showed that DHM markedly ameliorated osteogenic induction medium (OM)–induced osteogenic differentiation of hVICs, as evidenced by downregulation of ALP and Runx2 expression and decreased calcium deposition. The SwissTargetPrediction database was used to identify the potential AVC-associated direct protein target of DHM. Protein–protein interaction (PPI) analysis revealed that c-KIT, a tyrosine-protein kinase, can act as a credible protein target of DHM, as evidenced by molecular docking. Mechanistically, DHM-mediated inhibition of c-KIT phosphorylation drove interleukin-6 (IL-6) downregulation in CAVD, thereby ameliorating OM-induced osteogenic differentiation of hVICs and aortic valve calcification progression.

Conclusion: DHM ameliorates osteogenic differentiation of hVICs by blocking the phosphorylation of c-KIT, thus reducing IL-6 expression in CAVD. DHM could be a viable therapeutic supplement to impede CAVD.

Rac1 mediates cadherin-11 induced cellular pathogenic processes in aortic valve calcification

BACKGROUND

Calcific aortic valve disease (CAVD), a major cause for surgical aortic valve replacement, currently lacks available pharmacological treatments. Cadherin-11 (Cad11), a promising therapeutic target, promotes aortic valve calcification in vivo, but direct Cad11 inhibition in clinical trials has been unsuccessful. Targeting of downstream Cad11 effectors instead may be clinically useful; however, the downstream effectors that mediate Cad11-induced aortic valve cellular pathogenesis have not been investigated.

APPROACH AND RESULTS

Immunofluorescence of calcified human aortic valves revealed that GTP-Rac1 is highly upregulated in calcified leaflets and is 2.15 times more co-localized with Cad11 in calcified valves than GTP-RhoA. Using dominant negative mutants in porcine aortic valve interstitial cells (PAVICs), we show that Cad11 predominantly regulates Runx2 nuclear localization via Rac1. Rac1-GEF inhibition via NSC23766 effectively reduces calcification in ex vivo porcine aortic valve leaflets treated with osteogenic media by 2.8-fold and also prevents Cad11-induced cell migration, compaction, and calcification in PAVICs. GTP-Rac1 and Trio, a known Cad11 binding partner and Rac1-GEF, are significantly upregulated in Nfatc1Cre; R26-Cad11Tg/Tg (Cad11 OX) mice that conditionally overexpress Cad11 in the heart valves by 3.1-fold and 6.3-fold, respectively. Finally, we found that the Trio-specific Rac1-GEF inhibitor, ITX3, effectively prevents Cad11-induced calcification and Runx2 induction in osteogenic conditions.

CONCLUSION

Here we show that Cad11 induces many cellular pathogenic processes via Rac1 and that Rac1 inhibition effectively prevents many Cad11-induced aortic disease phenotypes. These findings highlight the therapeutic potential of blocking Rac1-GEFs in CAVD.

Shear and endothelial induced late-stage calcific aortic valve disease-on-a-chip develops calcium phosphate mineralizations

Calcific aortic valve disease (CAVD) is an active pathobiological process leading to severe aortic stenosis, where the only treatment is valve replacement. Late-stage CAVD is characterized by calcification, disorganization of collagen, and deposition of glycosaminoglycans, such as chondroitin sulfate (CS), in the fibrosa. We developed a three-dimensional microfluidic device of the aortic valve fibrosa to study the effects of shear stress (1 or 20 dyne per cm²), CS (1 or 20 mg mL^-1), and endothelial cell presence on calcification. CAVD chips consisted of a collagen I hydrogel, where porcine aortic valve interstitial cells were embedded within and porcine aortic valve endothelial cells were seeded on top of the matrix for up to 21 days. Here, we show that this CAVD-on-a-chip is the first to develop human-like calcified nodules varying in calcium phosphate mineralization maturity resulting from high shear and endothelial cells, specifically di- and octa-calcium phosphates. Long-term co-culture microfluidic studies confirmed cell viability and calcium phosphate formations throughout 21 days. Given that CAVD has no targeted therapies, the creation of a physiologically relevant test-bed of the aortic valve could lead to advances in preclinical studies.

Atypical Expression of Smooth Muscle Markers and Co-activators and Their Regulation in Rheumatic Aortic and Calcified Bicuspid Valves

Objective

We have previously reported that human calcified aortic cusps have abundant expression of smooth muscle (SM) markers and co-activators. We hypothesised that cells in bicuspid aortic valve (BAV) cusps and those affected by rheumatic heart valve (RHV) disease may follow a similar phenotypic transition into smooth muscle cells, a process that could be regulated by transforming growth factors (TGFs).

Aims

Cusps from eight patients with BAV and seven patients with RHV were analysed for early and late SM markers and regulators of SM gene expression by immunocytochemistry and compared to healthy aortic valves from 12 unused heart valve donors. The ability of TGFs to induce these markers in valve endothelial cells (VECs) on two substrates was assessed.

Results

In total, 7 out of 8 BAVs and all the RHVs showed an increased and atypical expression of early and late SM markers α-SMA, calponin, SM22 and SM-myosin. The SM marker co-activators were aberrantly expressed in six of the BAV and six of the RHV, in a similar regional pattern to the expression of SM markers. Additionally, regions of VECs, and endothelial cells lining the vessels within the cusps were found to be positive for SM markers and co-activators in three BAV and six RHV. Both BAVs and RHVs were significantly thickened and HIF1α expression was prominent in four BAVs and one RHV. The ability of TGFβs to induce the expression of SM markers and myocardin was greater in VECs cultured on fibronectin than on gelatin. Fibronectin was shown to be upregulated in BAVs and RHVs, within the cusps as well as in the basement membrane.

Conclusion

Bicuspid aortic valves and RHVs expressed increased numbers of SM marker-positive VICs and VECs. Concomittantly, these cells expressed MRTF-A and myocardin, key regulators of SM gene expression. TGFβ1 was able to preferentially upregulate SM markers and myocardin in VECs on fibronectin, and fibronectin was found to be upregulated in BAVs and RHVs. These findings suggest a role of VEC as a source of cells that express SM cell markers in BAVs and RHVs. The similarity between SM marker expression in BAVs and RHVs with our previous study with cusps from patients with aortic stenosis suggests the existance of a common pathological pathway between these different pathologies.

Uncoupling the Vicious Cycle of Mechanical Stress and Inflammation in Calcific Aortic Valve Disease

Calcific aortic valve disease (CAVD) is a common acquired valvulopathy, which carries a high burden of mortality. Chronic inflammation has been postulated as the predominant pathophysiological process underlying CAVD. So far, no effective medical therapies exist to halt the progression of CAVD. This review aims to outline the known pathways of inflammation and calcification in CAVD, focussing on the critical roles of mechanical stress and mechanosensing in the perpetuation of valvular inflammation. Following initiation of valvular inflammation, dysregulation of proinflammatory and osteoregulatory signalling pathways stimulates endothelial-mesenchymal transition of valvular endothelial cells (VECs) and differentiation of valvular interstitial cells (VICs) into active myofibroblastic and osteoblastic phenotypes, which in turn mediate valvular extracellular matrix remodelling and calcification. Mechanosensitive signalling pathways convert mechanical forces experienced by valve leaflets and circulating cells into biochemical signals and may provide the positive feedback loop that promotes acceleration of disease progression in the advanced stages of CAVD. Mechanosensing is implicated in multiple aspects of CAVD pathophysiology. The mechanosensitive RhoA/ROCK and YAP/TAZ systems are implicated in aortic valve leaflet mineralisation in response to increased substrate stiffness. Exposure of aortic valve leaflets, endothelial cells and platelets to high shear stress results in increased expression of mediators of VIC differentiation. Upregulation of the Piezo1 mechanoreceptor has been demonstrated to promote inflammation in CAVD, which normalises following transcatheter valve replacement. Genetic variants and inhibition of Notch signalling accentuate VIC responses to altered mechanical stresses. The study of mechanosensing pathways has revealed promising insights into the mechanisms that perpetuate inflammation and calcification in CAVD. Mechanotransduction of altered mechanical stresses may provide the sought-after coupling link that drives a vicious cycle of chronic inflammation in CAVD. Mechanosensing pathways may yield promising targets for therapeutic interventions and prognostic biomarkers with the potential to improve the management of CAVD.

Identification of the Relationship between Hub Genes and Immune Cell Infiltration in Vascular Endothelial Cells of Proliferative Diabetic Retinopathy Using Bioinformatics Methods

Background

Diabetic retinopathy (DR) is a serious ophthalmopathy that causes blindness, especially in the proliferative stage. However, the pathogenesis of its effect on endothelial cells, especially its relationship with immune cell infiltration, remains unclear.

Methods

The dataset GSE94019 was downloaded from the Gene Expression Omnibus (GEO) database to obtain DEGs. Through aggregate analyses such as Gene Ontology (GO) and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway enrichment analysis, a protein-protein interaction (PPI) network was constructed to analyze the potential function of DEGs. Weighted gene coexpression network analysis (WGCNA) and Cytoscape software including molecular complex detection (MCODE) and cytoHubba plug-ins were used to comprehensively analyze and determine the hub genes. ImmuCellAI analysis was performed to further study the relationship between samples, hub genes, and 24 types of immune cell infiltration. Finally, gene-set enrichment analysis (GSEA) was employed to identify the enrichment of immune cell infiltration and endothelial cell phenotype modifications in GO biological processes (BP) based on the expression level of hub genes.

Results

2393 DEGs were identified, of which 800 genes were downregulated, and 1593 genes were upregulated. The results of functional enrichment revealed that 1398 BP terms were significantly enriched in DEGs. Three hub genes, EEF1A1, RPL11, and RPS27A, which were identified by conjoint analysis using WGCNA and Cytoscape software, were positively correlated with the number of CD4 naive T cells and negatively correlated with the numbers of B cells. The number of CD4 naive T cells, T helper 2 (Th2) cells, and effector memory T (Tem) cells were significantly higher while CD8 naive T cells and B cells significantly were lower in the diabetic group than in the nondiabetic group.

Conclusions

We unearthed the DEGs and Hub genes of endothelial cells related to the pathogenesis of PDR: EEF1A1, RPL11, and RPS27A, which are highly related to each other and participate in the specific biological process of inflammation-related immune cell infiltration and endothelial cell development, chemotaxis, and proliferation, thus providing new perspectives into the diagnosis of and potential “killing two birds with one stone” targeted therapy for PDR.

The Complex Interplay of Inflammation, Metabolism, Epigenetics, and Sex in Calcific Disease of the Aortic Valve

Calcification of the aortic valve is one of the most rapidly increasing pathologies in the aging population worldwide. Traditionally associated to cardiovascular risk conditions, this pathology is still relatively unaddressed on a molecular/cellular standpoint and there are no available treatments to retard its progression unless valve substitution. In this review, we will describe some of the most involved inflammatory players, the metabolic changes that may be responsible of epigenetic modifications and the gender-related differences in the onset of the disease. A better understanding of these aspects and their integration into a unique pathophysiology context is relevant to improve current therapies and patients management.

Midkine Prevents Calcification of Aortic Valve Interstitial Cells via Intercellular Crosstalk

Calcified aortic valve disease (CAVD), the most common valvular heart disease, lacks pharmaceutical treatment options because its pathogenesis remains unclear. This disease with a complex macroenvironment characterizes notable cellular heterogeneity. Therefore, a comprehensive understanding of cellular diversity and cell-to-cell communication are essential for elucidating the mechanisms driving CAVD progression and developing therapeutic targets. In this study, we used single-cell RNA sequencing (scRNA-seq) analysis to describe the comprehensive transcriptomic landscape and cell-to-cell interactions. The transitional valvular endothelial cells (tVECs), an intermediate state during the endothelial-to-mesenchymal transition (EndMT), could be a target to interfere with EndMT progression. Moreover, matrix valvular interstitial cells (mVICs) with high expression of midkine (MDK) interact with activated valvular interstitial cells (aVICs) and compliment-activated valvular interstitial cells (cVICs) through the MK pathway. Then, MDK inhibited calcification of VICs that calcification was validated by Alizarin Red S staining, real-time quantitative polymerase chain reaction (RT-qPCR), and Western blotting assays in vitro. Therefore, we speculated that mVICs secreted MDK to prevent VICs’ calcification. Together, these findings delineate the aortic valve cells’ heterogeneity, underlining the importance of intercellular cross talk and MDK, which may offer a potential therapeutic strategy as a novel inhibitor of CAVD.

Innate immune cells in the pathophysiology of calcific aortic valve disease: lessons to be learned from atherosclerotic cardiovascular disease?

Calcific aortic valve disease (CAVD) is the most common valvular disease in the developed world with currently no effective pharmacological treatment available. CAVD results from a complex, multifactorial process, in which valvular inflammation and fibro-calcific remodelling lead to valve thickening and cardiac outflow obstruction. The exact underlying pathophysiology of CAVD is still not fully understood, yet the development of CAVD shows many similarities with the pathophysiology of atherosclerotic cardiovascular disease (ASCVD), such as coronary artery disease. Innate immune cells play a crucial role in ASCVD and might also play a pivotal role in the development of CAVD. This review summarizes the current knowledge on the role of innate immune cells, both in the circulation and in the aortic valve, in the development of CAVD and the similarities and differences with ASCVD. Trained immunity and clonal haematopoiesis of indeterminate potential are proposed as novel immunological mechanisms that possibly contribute to the pathophysiology of CAVD and new possible treatment targets are discussed.

Aortic valve cell microenvironment: Considerations for developing a valve-on-chip

Cardiac valves are sophisticated, dynamic structures residing in a complex mechanical and hemodynamic environment. Cardiac valve disease is an active and progressive disease resulting in severe socioeconomic burden, especially in the elderly. Valve disease also leads to a 50% increase in the possibility of associated cardiovascular events. Yet, valve replacement remains the standard of treatment with early detection, mitigation, and alternate therapeutic strategies still lacking. Effective study models are required to further elucidate disease mechanisms and diagnostic and therapeutic strategies. Organ-on-chip models offer a unique and powerful environment that incorporates the ease and reproducibility of in vitro systems along with the complexity and physiological recapitulation of the in vivo system. The key to developing effective valve-on-chip models is maintaining the cell and tissue-level microenvironment relevant to the study application. This review outlines the various components and factors that comprise and/or affect the cell microenvironment that ought to be considered while constructing a valve-on-chip model. This review also dives into the advancements made toward constructing valve-on-chip models with a specific focus on the aortic valve, that is, in vitro studies incorporating three-dimensional co-culture models that incorporate relevant extracellular matrices and mechanical and hemodynamic cues.

Valvular Endothelial Cell Response to the Mechanical Environment-A Review

Heart valve leaflets are complex structures containing valve endothelial cells, interstitial cells, and extracellular matrix. Heart valve endothelial cells sense mechanical stimuli, and communicate amongst themselves and the surrounding cells and extracellular matrix to maintain tissue homeostasis. In the presence of abnormal mechanical stimuli, endothelial cell communication is triggered in defense and such processes may eventually lead to cardiac disease progression. This review focuses on the role of mechanical stimuli on heart valve endothelial surfaces-from heart valve development and maintenance of tissue integrity to disease progression with related signal pathways involved in this process.

Calcific aortic valve disease: from molecular and cellular mechanisms to medical therapy

Calcific aortic valve disease (CAVD) is a highly prevalent condition that comprises a disease continuum, ranging from microscopic changes to profound fibro-calcific leaflet remodelling, culminating in aortic stenosis, heart failure, and ultimately premature death. Traditional risk factors, such as hypercholesterolaemia and (systolic) hypertension, are shared among atherosclerotic cardiovascular disease and CAVD, yet the molecular and cellular mechanisms differ markedly. Statin-induced low-density lipoprotein cholesterol lowering, a remedy highly effective for secondary prevention of atherosclerotic cardiovascular disease, consistently failed to impact CAVD progression or to improve patient outcomes. However, recently completed phase II trials provide hope that pharmaceutical tactics directed at other targets implicated in CAVD pathogenesis offer an avenue to alter the course of the disease non-invasively. Herein, we delineate key players of CAVD pathobiology, outline mechanisms that entail compromised endothelial barrier function, and promote lipid homing, immune-cell infiltration, and deranged phospho-calcium metabolism that collectively perpetuate a pro-inflammatory/pro-osteogenic milieu in which valvular interstitial cells increasingly adopt myofibro-/osteoblast-like properties, thereby fostering fibro-calcific leaflet remodelling and eventually resulting in left ventricular outflow obstruction. We provide a glimpse into the most promising targets on the horizon, including lipoprotein(a), mineral-binding matrix Gla protein, soluble guanylate cyclase, dipeptidyl peptidase-4 as well as candidates involved in regulating phospho-calcium metabolism and valvular angiotensin II synthesis and ultimately discuss their potential for a future therapy of this insidious disease.

Innate and adaptive immunity: the understudied driving force of heart valve disease

Calcific aortic valve disease (CAVD), and its clinical manifestation that is calcific aortic valve stenosis, is the leading cause for valve disease within the developed world, with no current pharmacological treatment available to delay or halt its progression. Characterized by progressive fibrotic remodelling and subsequent pathogenic mineralization of the valve leaflets, valve disease affects 2.5% of the western population, thus highlighting the need for urgent intervention. Whilst the pathobiology of valve disease is complex, involving genetic factors, lipid infiltration, and oxidative damage, the immune system is now being accepted to play a crucial role in pathogenesis and disease continuation. No longer considered a passive degenerative disease, CAVD is understood to be an active inflammatory process, involving a multitude of pro-inflammatory mechanisms, with both the adaptive and the innate immune system underpinning these complex mechanisms. Within the valve, 15% of cells evolve from haemopoietic origin, and this number greatly expands following inflammation, as macrophages, T lymphocytes, B lymphocytes, and innate immune cells infiltrate the valve, promoting further inflammation. Whether chronic immune infiltration or pathogenic clonal expansion of immune cells within the valve or a combination of the two is responsible for disease progression, it is clear that greater understanding of the immune systems role in valve disease is required to inform future treatment strategies for control of CAVD development.

Role of endothelial cells in pulmonary fibrosis via SREBP2 activation

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with limited treatment options. Despite endothelial cells (ECs) comprising 30% of the lung cellular composition, the role of EC dysfunction in pulmonary fibrosis (PF) remains unclear. We hypothesize that sterol regulatory element-binding protein 2 (SREBP2) plays a critical role in the pathogenesis of PF via EC phenotypic modifications. Transcriptome data demonstrate that SREBP2 overexpression in ECs led to the induction of the TGF, Wnt, and cytoskeleton remodeling gene ontology pathways and the increased expression of mesenchymal genes, such as snail family transcriptional repressor 1 (snai1), α-smooth muscle actin, vimentin, and neural cadherin. Furthermore, SREBP2 directly bound to the promoter regions and transactivated these mesenchymal genes. This transcriptomic change was associated with an epigenetic and phenotypic switch in ECs, leading to increased proliferation, stress fiber formation, and ECM deposition. Mice with endothelial-specific transgenic overexpression of SREBP2 (EC-SREBP2[N]-Tg mice) that were administered bleomycin to induce PF demonstrated exacerbated vascular remodeling and increased mesenchymal transition in the lung. SREBP2 was also found to be markedly increased in lung specimens from patients with IPF. These results suggest that SREBP2, induced by lung injury, can exacerbate PF in rodent models and in human patients with IPF.

The Individual and Combined Effects of Shear, Tension, and Flexure on Aortic Heart Valve Endothelial Cells in Culture

PURPOSE

The necessity of living engineered heart valves to treat patients with severe heart disease poses a challenge to tissue engineers. To reach such goal it is crucial to fully understand the role and the activities of valvular endothelial cells (VECs) when they face different types of mechanical stimuli. This study focuses on decomposing the roles of different mechanical stimuli on heart valve endothelial surfaces and the response of VECs in terms of morphology and phenotype change.

METHODS

This study utilizes soft hydrogel-based scaffolds to use as a substrate for cell culture to mimic heart valve tissue leaflet. VECs were cultured as a monolayer on the gel surface and different types of mechanical stimuli were applied. Finally, the response of cells was investigated in terms of morphology and protein expression changes.

RESULTS

Single stimuli introduces actin fibers reorganization in VECs, change in cell morphology, and higher mesenchymal protein expression. On the other hand, combined stimuli application has lower impact on actin fibers reorganization and cell morphology change, with lower mesenchymal protein expression.

CONCLUSIONS

When VECs face a single mechanical stimuli, they undergo transdifferentiation and transform into mesenchymal cells. However, when these cells face a combination of mechanical stimuli, the rate of transformation decreases compared to single stimuli applications. This indicates that a single stimulus induces endothelial to mesenchymal transition in VECs while the process is slower under the combination of multiple mechanical stimuli.

OCT4-mediated inflammation induces cell reprogramming at the origin of cardiac valve development and calcification

Cell plasticity plays a key role in embryos by maintaining the differentiation potential of progenitors. Whether postnatal somatic cells revert to an embryonic-like naïve state regaining plasticity and redifferentiate into a cell type leading to a disease remains intriguing. Using genetic lineage tracing and single-cell RNA sequencing, we reveal that Oct4 is induced by nuclear factor κB (NFκB) at embyronic day 9.5 in a subset of mouse endocardial cells originating from the anterior heart forming field at the onset of endocardial-to-mesenchymal transition. These cells acquired a chondro-osteogenic fate. OCT4 in adult valvular aortic cells leads to calcification of mouse and human valves. These calcifying cells originate from the Oct4 embryonic lineage. Genetic deletion of Pou5f1 (Pit-Oct-Unc, OCT4) in the endocardial cell lineage prevents aortic stenosis and calcification of ApoE^−/− mouse valve. We established previously unidentified self-cell reprogramming NFκB- and OCT4-mediated inflammatory pathway triggering a dose-dependent mechanism of valve calcification.

Chondroitin Sulfate Promotes Interstitial Cell Activation and Calcification in an In Vitro Model of the Aortic Valve

PURPOSE

Calcific aortic valve disease (CAVD), has been characterized as a cascade of cellular changes leading to leaflet thickening and valvular calcification. In diseased aortic valves, glycosaminoglycans (GAGs) normally found in the valve spongiosa migrate to the collagen I-rich fibrosa layer near calcified nodules. Current treatments for CAVD are limited to valve replacement or drugs tailored to other cardiovascular diseases.

METHODS

Porcine aortic valve interstitial cells and porcine aortic valve endothelial cells were seeded into collagen I hydrogels of varying initial stiffness or initial stiffness-matched collagen I hydrogels containing the glycosaminoglycans chondroitin sulfate (CS), hyaluronic acid (HA), or dermatan sulfate (DS). Assays were performed after 2 weeks in culture to determine cell gene expression, protein expression, protein secretion, and calcification. Multiple regression analyses were performed to determine the importance of initial hydrogel stiffness, GAGs, and the presence of endothelial cells on calcification, both with and without osteogenic medium.

RESULTS

High initial stiffness hydrogels and osteogenic medium promoted calcification, while for DS or HA the presence of endothelial cells prevented calcification. CS was found to increase the expression of pro-calcific genes, increase activated myofibroblast protein expression, induce the secretion of collagen I by activated interstitial cells, and increase calcified nodule formation.

CONCLUSION

This study demonstrates a more complete model of aortic valve disease, including endothelial cells, interstitial cells, and a stiff and disease-like ECM. In vitro models of both healthy and diseased valves can be useful for understanding the mechanisms of CAVD pathogenesis and provide a model for testing novel therapeutics.

Regulation of Partial and Reversible Endothelial-to-Mesenchymal Transition in Angiogenesis

During development and in several diseases, endothelial cells (EC) can undergo complete endothelial-to-mesenchymal transition (EndoMT or EndMT) to generate endothelial-derived mesenchymal cells. Emerging evidence suggests that ECs can also undergo a partial EndoMT to generate cells with intermediate endothelial- and mesenchymal-character. This partial EndoMT event is transient, reversible, and supports both developmental and pathological angiogenesis. Here, we discuss possible regulatory mechanisms that may control the EndoMT program to dictate whether cells undergo complete or partial mesenchymal transition, and we further consider how these pathways might be targeted therapeutically in cancer.

Interferons Are Pro-Inflammatory Cytokines in Sheared-Stressed Human Aortic Valve Endothelial Cells

Calcific aortic valve disease (CAVD) is an athero-inflammatory process. Growing evidence supports the inflammation-driven calcification model, mediated by cytokines such as interferons (IFNs) and tumor necrosis factor (TNF)-α. Our goal was investigating IFNs' effects in human aortic valve endothelial cells (VEC) and the potential differences between aortic (aVEC) and ventricular (vVEC) side cells. The endothelial phenotype was analyzed by Western blot, qPCR, ELISA, monocyte adhesion, and migration assays. In mixed VEC populations, IFNs promoted the activation of signal transducers and activators of transcription-1 and nuclear factor-κB, and the subsequent up-regulation of pro-inflammatory molecules. Side-specific VEC were activated with IFN-γ and TNF-α in an orbital shaker flow system. TNF-α, but not IFN-γ, induced hypoxia-inducible factor (HIF)-1α stabilization or endothelial nitric oxide synthase downregulation. Additionally, IFN-γ inhibited TNF-α-induced migration of aVEC. Also, IFN-γ triggered cytokine secretion and adhesion molecule expression in aVEC and vVEC. Finally, aVEC were more prone to cytokine-mediated monocyte adhesion under multiaxial flow conditions as compared with uniaxial flow. In conclusion, IFNs promote inflammation and reduce TNF-α-mediated migration in human VEC. Moreover, monocyte adhesion was higher in inflamed aVEC sheared under multiaxial flow, which may be relevant to understanding the initial stages of CAVD.

The Mechanobiology of Endothelial-to-Mesenchymal Transition in Cardiovascular Disease

Endothelial cells (ECs) lining the cardiovascular system are subjected to a highly dynamic microenvironment resulting from pulsatile pressure and circulating blood flow. Endothelial cells are remarkably sensitive to these forces, which are transduced to activate signaling pathways to maintain endothelial homeostasis and respond to changes in the environment. Aberrations in these biomechanical stresses, however, can trigger changes in endothelial cell phenotype and function. One process involved in this cellular plasticity is endothelial-to-mesenchymal transition (EndMT). As a result of EndMT, ECs lose cell-cell adhesion, alter their cytoskeletal organization, and gain increased migratory and invasive capabilities. EndMT has long been known to occur during cardiovascular development, but there is now a growing body of evidence also implicating it in many cardiovascular diseases (CVD), often associated with alterations in the cellular mechanical environment. In this review, we highlight the emerging role of shear stress, cyclic strain, matrix stiffness, and composition associated with EndMT in CVD. We first provide an overview of EndMT and context for how ECs sense, transduce, and respond to certain mechanical stimuli. We then describe the biomechanical features of EndMT and the role of mechanically driven EndMT in CVD. Finally, we indicate areas of open investigation to further elucidate the complexity of EndMT in the cardiovascular system. Understanding the mechanistic underpinnings of the mechanobiology of EndMT in CVD can provide insight into new opportunities for identification of novel diagnostic markers and therapeutic interventions.

Aortic valve disease in diabetes: Molecular mechanisms and novel therapies

Valve disease and particularly calcific aortic valve disease (CAVD) and diabetes (DM) are progressive diseases constituting a global health burden for all aging societies (Progress in Cardiovascular Diseases. 2014;56(6):565: Circulation Research. 2021;128(9):1344). Compared to non‐diabetic individuals (The Lancet. 2008;371(9626):1800: The American Journal of Cardiology. 1983;51(3):403: Journal of the American College of Cardiology. 2017;69(12):1523), the diabetic patients have a significantly greater propensity for cardiovascular disorders and faster degeneration of implanted bioprosthetic aortic valves. Previously, using an original experimental model, the diabetic‐hyperlipemic hamsters, we have shown that the earliest alterations induced by these conditions occur at the level of the aortic valves and, with time these changes lead to calcifications and CAVD. However, there are no pharmacological treatments available to reverse or retard the progression of aortic valve disease in diabetes, despite the significant advances in the field. Therefore, it is critical to uncover the mechanisms of valve disease progression, find biomarkers for diagnosis and new targets for therapies. This review aims at presenting an update on the basic research in CAVD in the context of diabetes. We provide an insight into the accumulated data including our results on diabetes‐induced progressive cell and molecular alterations in the aortic valve, new potential biomarkers to assess the evolution and therapy of the disease, advancement in targeted nanotherapies, tissue engineering and the potential use of circulating endothelial progenitor cells in CAVD.

Glucotoxicity Activation of IL6 and IL11 and Subsequent Induction of Fibrosis May Be Involved in the Pathogenesis of Islet Dysfunction

Background: Islet dysfunction is the main pathological process of type 2 diabetes mellitus (T2DM). Fibrosis causes islet dysfunction, but the current mechanism is still unclear. Here, bioinformatics analysis identified gene clusters closely related to T2DM and differentially expressed genes related to fibrosis, and animal models verified the roles of these genes.

Methods: Human islet transcriptomic datasets were obtained from the Gene Expression Omnibus (GEO), and weighted gene coexpression network analysis (WGCNA) was applied to screen the key gene modules related to T2DM and analyze the correlations between the modules and clinical characteristics. Enrichment analysis was performed to identify the functions and pathways of the key module genes. WGCNA, protein-protein interaction (PPI) analysis and receiver operating characteristic (ROC) curve analysis were used to screen the hub genes. The hub genes were verified in another GEO dataset, the islets of high-fat diet (HFD)-fed Sprague-Dawley rats were observed by H&E and Masson’s trichrome staining, the fibrotic proteins were verified by immunofluorescence, and the hub genes were tested by immunohistochemistry.

Results: The top 5,000 genes were selected according to the median absolute deviation, and 18 modules were analyzed. The yellow module was highly associated with T2DM, and its positive correlation with glycated hemoglobin (HbA1c) was significantly stronger than that with body mass index (BMI). Enrichment analysis revealed that extracellular matrix organization, the collagen-containing extracellular matrix and cytokine−cytokine receptor interaction might influence T2DM progression. The top three hub genes, interleukin 6 (IL6), IL11 and prostaglandin-endoperoxide synthase 2 (PTGS2), showed upregulated expression in T2DM. In the validation dataset, IL6, IL11, and PTGS2 levels were upregulated in T2DM, and IL6 and PTGS2 expression was positively correlated with HbA1c and BMI; however, IL11 was positively correlated only with HbA1c. In HFD-fed Sprague-Dawley rats, the positive of IL6 and IL11 in islets was stronger, but PTGS2 expression was not significantly altered. The extent of fibrosis, irregular cellular arrangement and positive actin alpha 2 (ACTA2) staining in islets was significantly greater in HFD-fed rats than in normal diet-fed rats.

Conclusion: Glucotoxicity is a major factor leading to increased IL6 and IL11 expression, and IL6-and IL11-induced fibrosis might be involved in islet dysfunction.

Endothelial Heterogeneity in Development and Wound Healing

The vasculature is comprised of endothelial cells that are heterogeneous in nature. From tissue resident progenitors to mature differentiated endothelial cells, the diversity of these populations allows for the formation, maintenance, and regeneration of the vascular system in development and disease, particularly during situations of wound healing. Additionally, the de-differentiation and plasticity of different endothelial cells, especially their capacity to undergo endothelial to mesenchymal transition, has also garnered significant interest due to its implication in disease progression, with emphasis on scarring and fibrosis. In this review, we will pinpoint the seminal discoveries defining the phenotype and mechanisms of endothelial heterogeneity in development and disease, with a specific focus only on wound healing.

Endothelial-Mesenchymal Transition in Cardiovascular Disease

Endothelial-to-mesenchymal transition is a dynamic process in which endothelial cells suppress constituent endothelial properties and take on mesenchymal cell behaviors. To begin the process, endothelial cells loosen their cell-cell junctions, degrade the basement membrane, and migrate out into the perivascular surroundings. These initial endothelial behaviors reflect a transient modulation of cellular phenotype, that is, a phenotypic modulation, that is sometimes referred to as partial endothelial-to-mesenchymal transition. Loosening of endothelial junctions and migration are also seen in inflammatory and angiogenic settings such that endothelial cells initiating endothelial-to-mesenchymal transition have overlapping behaviors and gene expression with endothelial cells responding to inflammatory signals or sprouting to form new blood vessels. Reduced endothelial junctions increase permeability, which facilitates leukocyte trafficking, whereas endothelial migration precedes angiogenic sprouting and neovascularization; both endothelial barriers and quiescence are restored as inflammatory and angiogenic stimuli subside. Complete endothelial-to-mesenchymal transition proceeds beyond phenotypic modulation such that mesenchymal characteristics become prominent and endothelial functions diminish. In proadaptive, regenerative settings the new mesenchymal cells produce extracellular matrix and contribute to tissue integrity whereas in maladaptive, pathologic settings the new mesenchymal cells become fibrotic, overproducing matrix to cause tissue stiffness, which eventually impacts function. Here we will review what is known about how TGF (transforming growth factor) β influences this continuum from junctional loosening to cellular migration and its relevance to cardiovascular diseases.