Basic mechanisms of calcific aortic valve disease

Surgical aortic valve replacement in patients with reduced ejection fraction. Prevalence and follow-up

INTRODUCTION

Limited information exists on the prevalence and outcomes of patients undergoing surgical aortic valve replacement (SAVR) for aortic stenosis (AS) with reduced left ventricular ejection fraction (LVEF). This study aims to describe the number of AS patients undergoing SAVR with LVEF less than 55 % and quantify LVEF improvement at follow-up.

MATERIAL AND METHODS

We analyzed patients undergoing SAVR with LVEF less than 55 % and the number of patients that improved the LVEF at 6 months. We defined 'improved LVEF' as a 10 % increase of LVEF compared to baseline.

RESULTS

Out of 685 patients, 11.4 % (n = 78) had SAVR with LVEF <55 %. The median pre-surgery LVEF was 45 % [IQR 37-51]. In-hospital mortality was 5.1 % (n = 4). Follow-up data for 69 patients showed 50.7 % (n = 35) had improved LVEF.

CONCLUSIONS

In our cohort, 10 % of severe AS patients underwent SAVR with LVEF <55 %, with half showing LVEF improvement at follow-up.

Integrated bioinformatics analysis identified leucine rich repeat containing 15 and secreted phosphoprotein 1 as hub genes for calcific aortic valve disease and osteoarthritis

Calcific aortic valve disease (CAVD) and osteoarthritis (OA) are common diseases in the ageing population and share similar pathogenesis, especially in inflammation. This study aims to discover potential diagnostic and therapeutic targets in patients with CAVD and OA. Three CAVD datasets and one OA dataset were obtained from the Gene Expression Omnibus database. We used bioinformatics methods to search for key genes and immune infiltration, and established a ceRNA network. Immunohistochemical staining was performed to verify the expression of candidate genes in human and mice aortic valve tissues. Two key genes obtained, leucine rich repeat containing 15 (LRRC15) and secreted phosphoprotein 1 (SPP1), were further screened using machine learning and verified in human and mice aortic valve tissues. Compared to normal tissues, the infiltration of immune cells in CAVD tissues was significantly higher, and the expressions of LRRC15 and SPP1 were positively correlated with immune cells infiltration. Moreover, the ceRNA network showed extensive regulatory interactions based on LRRC15 and SPP1. The authors' findings identified LRRC15 and SPP1 as hub genes in immunological mechanisms during CAVD and OA initiation and progression, as well as potential targets for drug development.

Investigation of autophagy‑related genes and immune infiltration in calcific aortic valve disease: A bioinformatics analysis and experimental validation

The present study aimed to elucidate the role of autophagy-related genes (ARGs) in calcific aortic valve disease (CAVD) and their potential interactions with immune infiltration via experimental verification and bioinformatics analysis. A total of three microarray datasets (GSE12644, GSE51472 and GSE77287) were obtained from the Gene Expression Omnibus database, and gene set enrichment analysis was performed to identify the relationship between autophagy and CAVD. After differentially expressed genes and differentially expressed ARGs (DEARGs) were identified using CAVD samples and normal aortic valve samples, a functional analysis was performed, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses, protein-protein interaction network construction, hub gene identification and validation, immune infiltration and drug prediction. The results of the present study indicated a significant relationship between autophagy and CAVD. A total of 46 DEARGs were identified. GO and pathway enrichment analyses revealed the complex roles of DEARGs in regulating CAVD, including multiple gene functions and pathways. A total of 10 hub genes were identified, with three (SPP1, CXCL12 and CXCR4) consistently upregulated in CAVD samples compared with normal aortic valve samples in multiple datasets and experimental validation. Immune infiltration analyses demonstrated significant differences in immune cell proportions between CAVD samples and normal aortic valve samples, thus showing the crucial role of immune infiltration in CAVD development. Furthermore, therapeutic drugs were predicted that could target the identified hub genes, including bisphenol A, resveratrol, progesterone and estradiol. In summary, the present study illuminated the crucial role of autophagy in CAVD development and identified key ARGs as potential therapeutic targets. In addition, the observed immune cell infiltration and predicted autophagy-related drugs suggest promising avenues for future research and novel CAVD treatments.

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.

Capsaicin inhibits aortic valvular interstitial cell calcification via the redox-sensitive NFκB/AKT/ERK1/2 pathway

Calcific aortic valve stenosis (CAVS), the third most prevalent cardiovascular disorder is known to impose a huge social and economic burden on patients. However, no pharmacotherapy has yet been established. Aortic valve replacement is the only treatment option, although its lifelong efficacy is not guaranteed and involves inevitable complications. So, there is a crucial need to find novel pharmacological targets to delay or prevent CAVS progression. Capsaicin is well known for its anti-inflammatory and antioxidant properties and has recently been revealed to inhibit arterial calcification. We thus investigated the effect of capsaicin in attenuating aortic valve interstitial cells (VICs) calcification induced by pro-calcifying medium (PCM). Capsaicin reduced the level of calcium deposition in calcified VICs, along with reductions in gene and protein expression of the calcification markers Runx2, osteopontin, and BMP2. Based on Gene Ontology biological process and Kyoto Encyclopedia of Genes and Genomes pathway analysis oxidative stress, AKT and AGE-RAGE signaling pathways were selected. The AGE-RAGE signaling pathway activates oxidative stress and inflammation-mediated pathways including ERK and NFκB signaling pathways. Capsaicin successfully inhibited oxidative stress- and reactive oxygen species-related markers NOX2 and p22^phox. The markers of the AKT, ERK1/2, and NFκB signaling pathways, namely, phosphorylated AKT, ERK1/2, NFκB, and IκBα were upregulated in calcified cells, while being significantly downregulated upon capsaicin treatment. Capsaicin attenuates VICs calcification in vitro by inhibition of redox-sensitive NFκB/AKT/ERK1/2 signaling pathway, indicating its potential as a candidate to alleviate CAVS.

Identification of key genes involved in calcific aortic valve disease based on integrated bioinformatics analysis

The calcific aortic valve disease (CAVD) develops as an aortic valve sclerosis and progresses to an advanced form of stenosis. In many biological fields, bioinformatics becomes a fundamental component. The key mechanisms involved in CAVD are discovered with the use of bioinformatics to investigate gene function and pathways. We downloaded the original data (GSE51472) from the Gene Expression Omnibus (GEO) database (http://www.ncbi.nlm.nih.gov/geo/). After standardization, 2978 differentially expressed genes (DEGs) were identified from the data sets GSE51472 containing samples from normal, calcified, and sclerotic aortic valves. Analysis of DEGs based on the series test of clusters (STCs) revealed the two most significant patterns. Based on the result of the STC, the functional enrichment analysis of gene ontology (GO) was conducted to investigate the molecular function (MF), biological process (BP), and cell compound (CC) of the DEGs. With a p value of 0.01, DEGs associated with "chronic inflammation," "T-cell receptor complexes," and "antigen binding" had the highest significance within BP, CC, and MF. DEG enrichment in signaling pathways was analyzed using KEGG pathway enrichment. Using a p < 0.05 level of significance, the most enriched biological pathways related to CAVD were "Chemokine signaling pathway," "Cytokine-cytokine receptor interaction," "Tuberculosis," "PI3K-Akt signaling pathway," and "Transcriptional misregulation in cancer." Finally, the construction of gene co-expression networks and pathway networks illustrated the pathogensis of CAVD. TLR2, CD86, and TYROBP were identified as hub genes for the development of CAVD. Moreover, "MAPK signaling pathway," "Apoptosis," and "Pathways in cancer" were regarded as the core pathways among the samples of normal, sclerotic and calcified aortic valve samples.

Calcific Aortic Valve Stenosis with Aging and Current Development in its Pathophysiology

Aortic stenosis is the most common valvular heart disease affecting the elderly. While most patients have a prolonged asymptomatic phase, the development of symptoms ushers in a phase clinical deterioration that often leads to sudden death without an intervention. Treatment of aortic stenosis with valve replacement often relieves the symptoms but still leaves behind a remodeled left ventricle which may not recover. Understanding the pathophysiology of aortic stenosis and realizing that the disease process may be a more active biological entity rather than a passive degenerative process will help us prevent it. This review serves to summarize the latest literature on the pathophysiology of aortic stenosis in the elderly.

[Optimal time window for observation of calcific aortic valve disease in mice following catheter-induced valve injury]

OBJECTIVE

To investigate the optimal time window for observation of catheter-induced valve injury that mimics calcified aortic valve disease in mice.

METHODS

A catheter was inserted into the right common carotid artery of 8-week-old C57BL6 mice under ultrasound guidance, and aortic valve injury was induced using the guide wire.At 4, 8 and 16 weeks after modeling, the mice were subjected to ultrasound measurement of the heart short axial shortening rate, aortic valve peak velocity and aortic valve orifice area.Grain-Eosin staining was used to observe the changes in the thickness of the aortic valve, and calcium deposition in the aortic valve was assessed using Alizarin red staining.Immunofluorescence assay was performed to detect the expression of alkaline phosphatase (ALP) in the aortic valve.

RESULTS

At 4, 8 and 16 weeks after modeling, valve thickness (P=0.002), calcium deposition (P < 0.0001) and the expression of osteogenic protein ALP (P=0.0016) were significantly increased, but their increments were comparable at the 3 time points of observation.

CONCLUSION

In mouse models of calcific aortic valve disease induced by catheter valve injury, 4 weeks after the injury appears to be the optimal time window for observation of pathophysiological changes in the aortic valves to avoid further increase of the death rate of the mice over time.

Upregulation of miR-664a-3p Ameliorates Calcific Aortic Valve Disease by Inhibiting the BMP2 Signaling Pathway

The development of calcific aortic valve disease (CAVD) is a complex process of ectopic calcification involving various factors that lead to aortic valve stenosis, hemodynamic changes, and, in severe cases, even sudden death. Currently, aortic valve replacement is the only effective method. The osteogenic differentiation of aortic valve interstitial cells (AVICs) is one of the key factors of valve calcification. Emerging evidence suggests that bone morphogenetic protein 2 (BMP2) can induce the proosteogenic activation of AVICs. However, the regulatory mechanism underlying this activation in AVICs is unclear. In the present study, we elucidated through high-throughput RNA sequencing and RT-qPCR that miR-664a-3p was evidently downregulated in the calcific aortic valve. We also proved that miR-664a-3p was involved in regulating osteogenic differentiation in AVICs. Target prediction analysis and dual-luciferase reporter gene assay confirmed that miR-664a-3p is preferentially bound to BMP2. Furthermore, the effect of the miR-664a-3p/BMP2 axis on osteogenic differentiation in AVICs was examined using the gain- and loss-of-function approach. Finally, we constructed a mouse CAVD model and verified the effect of the miR-664a-3p/BMP2 axis on the aortic valve calcification leaflets in vivo. In conclusion, miR-664a-3p regulates osteogenic differentiation in AVICs through negative regulation of BMP2, highlighting that miR-664a-3p may be a potential therapeutic target for CAVD.

Marine-Derived Piericidin Diglycoside S18 Alleviates Inflammatory Responses in the Aortic Valve via Interaction with Interleukin 37

Calcific aortic valve disease (CAVD) is a valvular disease frequently in the elderly individuals that can lead to the valve dysfunction. Osteoblastic differentiation of human aortic valve interstitial cells (HAVICs) induced by inflammation play a crucial role in CAVD pathophysiological processes. To date, no effective drugs for CAVD have been established, and new agents are urgently needed. Piericidin glycosides, obtained from a marine-derived Streptomyces strain, were revealed to have regulatory effects on mitochondria in previous studies. Here, we discovered that 13-hydroxypiericidin A 10-O-α-D-glucose (1→6)-β-D-glucoside (S18), a specific piericidin diglycoside, suppresses lipopolysaccharide- (LPS) induced inflammatory responses of HAVICs by alleviating mitochondrial stress in an interleukin (IL)-37-dependent manner. Knockdown of IL-37 by siRNA not only exaggerated LPS-induced HAVIC inflammation and mitochondrial stress but also abrogated the anti-inflammatory effect of S18 on HAVICs. Moreover, S18 alleviated aortic valve lesions in IL-37 transgenic mice of CAVD model. Microscale thermophoresis (MST) and docking analysis of five piericidin analogues suggested that diglycosides, but not monoglycosides, exert obvious IL-37-binding activity. These results indicate that S18 directly binds to IL-37 to alleviate inflammatory responses in HAVICs and aortic valve lesions in mice. Piericidin diglycoside S18 is a potential therapeutic agent to prevent the development of CAVD.

Implication of Lipids in Calcified Aortic Valve Pathogenesis: Why Did Statins Fail?

Calcific Aortic Valve Disease (CAVD) is a fibrocalcific disease. Lipoproteins and oxidized phospholipids play a substantial role in CAVD; the level of Lp(a) has been shown to accelerate the progression of valve calcification. Indeed, oxidized phospholipids carried by Lp(a) into the aortic valve stimulate endothelial dysfunction and promote inflammation. Inflammation and growth factors actively promote the synthesis of the extracellular matrix (ECM) and trigger an osteogenic program. The accumulation of ECM proteins promotes lipid adhesion to valve tissue, which could initiate the osteogenic program in interstitial valve cells. Statin treatment has been shown to have the ability to diminish the death rate in subjects with atherosclerotic impediments by decreasing the serum LDL cholesterol levels. However, the use of HMG-CoA inhibitors (statins) as cholesterol-lowering therapy did not significantly reduce the progression or the severity of aortic valve calcification. However, new clinical trials targeting Lp(a) or PCSK9 are showing promising results in reducing the severity of aortic stenosis. In this review, we discuss the implication of lipids in aortic valve calcification and the current findings on the effect of lipid-lowering therapy in aortic stenosis.

The Natural Product Andrographolide Ameliorates Calcific Aortic Valve Disease by Regulating the Proliferation of Valve Interstitial Cells via the MAPK-ERK Pathway

Calcific aortic valve disease (CAVD) is an active pathobiological process that involves fibrosis and calcification of aortic valve leaflets, thereby causing cardiac hemodynamic changes and eventually heart failure. Cell proliferation changes at the initial stage of CAVD are an important target for pharmaceutical intervention. This study aimed to investigate whether andrographolide (AGP) could inhibit the proliferation of valve interstitial cells (VICs) in vitro and in vivo to delay the process of CAVD. Cell proliferative factors were tested in both healthy and CAVD aortic valve samples. Cell cycle, cell growth, and calcification of VICs were assessed using flow cytometry, CCK8 assay, EdU staining, and Alizarin Red S staining. The expression of cell proliferative factors and osteogenic factors were quantified by qRT-PCR or immunofluorescence staining. The interaction between AGP and ERK (extracellular regulated protein kinases) was detected by molecular docking. In addition, a high-fat diet-fed animal model was used to verify the effect of AGP on CAVD in vivo. In conclusion, we found that AGP ameliorates aortic valve incrassation by inhibiting cell proliferation via the MAPK-ERK signaling pathway. Therefore, AGP is a promising drug that prevents the occurrence of CAVD via regulating cell proliferation.

Prioritization of Candidate Biomarkers for Degenerative Aortic Stenosis through a Systems Biology-Based In-Silico Approach

Degenerative aortic stenosis is the most common valve disease in the elderly and is usually confirmed at an advanced stage when the only treatment is surgery. This work is focused on the study of previously defined biomarkers through systems biology and artificial neuronal networks to understand their potential role within aortic stenosis. The goal was generating a molecular panel of biomarkers to ensure an accurate diagnosis, risk stratification, and follow-up of aortic stenosis patients. We used in silico studies to combine and re-analyze the results of our previous studies and, with information from multiple databases, established a mathematical model. After this, we prioritized two proteins related to endoplasmic reticulum stress, thrombospondin-1 and endoplasmin, which have not been previously validated as markers for aortic stenosis, and analyzed them in a cell model and in plasma from human subjects. Large-scale bioinformatics tools allow us to extract the most significant results after using high throughput analytical techniques. Our results could help to prevent the development of aortic stenosis and open the possibility of a future strategy based on more specific therapies.

Bioinformatics and Machine Learning Methods to Identify FN1 as a Novel Biomarker of Aortic Valve Calcification

Aim

The purpose of this study was to identify potential diagnostic markers for aortic valve calcification (AVC) and to investigate the function of immune cell infiltration in this disease.

Methods

The AVC data sets were obtained from the Gene Expression Omnibus. The identification of differentially expressed genes (DEGs) and the performance of functional correlation analysis were carried out using the R software. To explore hub genes related to AVC, a protein–protein interaction network was created. Diagnostic markers for AVC were then screened and verified using the least absolute shrinkage and selection operator, logistic regression, support vector machine-recursive feature elimination algorithms, and hub genes. The infiltration of immune cells into AVC tissues was evaluated using CIBERSORT, and the correlation between diagnostic markers and infiltrating immune cells was analyzed. Finally, the Connectivity Map database was used to forecast the candidate small molecule drugs that might be used as prospective medications to treat AVC.

Results

A total of 337 DEGs were screened. The DEGs that were discovered were mostly related with atherosclerosis and arteriosclerotic cardiovascular disease, according to the analyses. Gene sets involved in the chemokine signaling pathway and cytokine–cytokine receptor interaction were differently active in AVC compared with control. As the diagnostic marker for AVC, fibronectin 1 (FN1) (area the curve = 0.958) was discovered. Immune cell infiltration analysis revealed that the AVC process may be mediated by naïve B cells, memory B cells, plasma cells, activated natural killer cells, monocytes, and macrophages M0. Additionally, FN1 expression was associated with memory B cells, M0 macrophages, activated mast cells, resting mast cells, monocytes, and activated natural killer cells. AVC may be reversed with the use of yohimbic acid, the most promising small molecule discovered so far.

Conclusion

FN1 can be used as a diagnostic marker for AVC. It has been shown that immune cell infiltration is important in the onset and progression of AVC, which may benefit in the improvement of AVC diagnosis and treatment.

MicroRNA-22 promoted osteogenic differentiation of valvular interstitial cells by inhibiting CAB39 expression during aortic valve calcification

Calcific aortic valve disease (CAVD) is a common valve disease characterized by the fibro-calcific remodeling of the aortic valves, which is an actively regulated process involving osteogenic differentiation of valvular interstitial cells (VICs). MicroRNA (miRNA) is an essential regulator in diverse biological processes in cells. The present study aimed to explore the role and mechanism of miR-22 in the osteogenic differentiation of VICs. The expression profile of osteogenesis-related miRNAs was first detected in aortic valve tissue from CAVD patients (n = 33) and healthy controls (n = 12). miR-22 was highly expressed in calcified valve tissues (P < 0.01), and the expression was positively correlated with the expression of OPN (rs = 0.820, P < 0.01) and Runx2 (rs = 0.563, P < 0.01) in VICs isolated from mild or moderately calcified valves. The sustained high expression of miR-22 was also validated in an in-vitro VICs osteogenic model. Adenovirus-mediated gain-of-function and loss-of-function experiments were then performed. Overexpression of miR-22 significantly accelerated the calcification process of VICs, manifested by significant increases in calcium deposition, alkaline phosphate activity, and expression of osteoblastic differentiation markers. Conversely, inhibition of miR-22 significantly negated the calcification process. Subsequently, calcium-binding protein 39 (CAB39) was identified as a target of miR-22. Overexpression of miR-22 significantly reduced the expression of CAB39 in VICs, leading to decreased catalytic activity of the CAB39-LKB1-STRAD complex, which, in turn, exacerbated changes in the AMPK-mTOR signaling pathway, and ultimately accelerated the calcification process. In addition, ROS generation and autophagic activity during VIC calcification were also regulated by miR-22/CAB39 pathway. These results indicate that miR-22 is an important accelerator of the osteogenic differentiation of VICs, and a potential therapeutic target in CAVD.

Lipoprotein(a), a Lethal Player in Calcific Aortic Valve Disease

Calcified aortic valve disease (CAVD) is the most common valvular cardiovascular disease with increasing incidence and mortality. The primary treatment for CAVD is surgical or transcatheter aortic valve replacement and there remains a lack of effective drug treatment. Recently, lipoprotein (a) (Lp(a)) has been considered to play a crucial role in CAVD pathophysiology. Multiple studies have shown that Lp(a) represents an independent risk factor for CAVD. Moreover, Lp(a) mediates the occurrence and development of CAVD by affecting aortic valve endothelial dysfunction, indirectly promoting foam cell formation through oxidized phospholipids (OxPL), inflammation, oxidative stress, and directly promotes valve calcification. However, there is a lack of clinical trials with Lp(a) reduction as a primary endpoint. This review aims to explore the relationship and mechanism between Lp(a) and CAVD, and focuses on the current drugs that can be used as potential therapeutic targets for CAVD.

Mechanism of Endoplasmic Reticulum Stress Pathway in the Osteogenic Phenotypic Transformation of Aortic Valve Interstitial Cells

BACKGROUND AND PURPOSE

Calcific Aortic Valve Disease (CAVD) is a crucial component of degenerative valvular disease in old age and with the increasing prevalence of the aging population. we hope that by modeling valvular osteogenesis and intervening with endoplasmic reticulum stress inhibitor TUDCA to observe the effect of endoplasmic reticulum stress on valve osteogenesis.

METHODS

In this study, rabbit heart valvular interstitial cells (VICs) were isolated and cultured. They treated with ox-LDL (Oxidized Low Density Lipoprotein) stimulation to establish a model of valvular osteogenic transformation. BMP2 (Bone Morphogenetic Protein 2), PERK (Protein kinase R-like endoplasmic reticulum kinase), CHOP (CCAAT/enhancer-binding protein homologous protein) and transcriptional regulatory factor ATF4 (Activating Transcription Factor 4 )were recorded after intervention with ER stress inhibitor TUDCA. The effects of er stress on valvular osteogenic transformation were analyzed.

RESULT

After stimulation of VICs with ox-LDL, the expression levels of BMP2, PERK, CHOP, and ATF4 increased. However, TUDCA treatment can alleviate the increased expression levels of BMP2, PERK ATF4, and CHOP under ox-LDL stimulation to a certain extent.

CONCLUSION

The endoplasmic reticulum stress signaling pathway is involved in ox-LDL-induced calcification of rabbit valve interstitial cells. Inhibition of endoplasmic reticulum stress using TUDCA can improve the progression of rabbit aortic valve calcification.

NOTCH Signaling in Aortic Valve Development and Calcific Aortic Valve Disease

NOTCH intercellular signaling mediates the communications between adjacent cells involved in multiple biological processes essential for tissue morphogenesis and homeostasis. The NOTCH1 mutations are the first identified human genetic variants that cause congenital bicuspid aortic valve (BAV) and calcific aortic valve disease (CAVD). Genetic variants affecting other genes in the NOTCH signaling pathway may also contribute to the development of BAV and the pathogenesis of CAVD. While CAVD occurs commonly in the elderly population with tri-leaflet aortic valve, patients with BAV have a high risk of developing CAVD at a young age. This observation indicates an important role of NOTCH signaling in the postnatal homeostasis of the aortic valve, in addition to its prenatal functions during aortic valve development. Over the last decade, animal studies, especially with the mouse models, have revealed detailed information in the developmental etiology of congenital aortic valve defects. In this review, we will discuss the molecular and cellular aspects of aortic valve development and examine the embryonic pathogenesis of BAV. We will focus our discussions on the NOTCH signaling during the endocardial-to-mesenchymal transformation (EMT) and the post-EMT remodeling of the aortic valve. We will further examine the involvement of the NOTCH mutations in the postnatal development of CAVD. We will emphasize the deleterious impact of the embryonic valve defects on the homeostatic mechanisms of the adult aortic valve for the purpose of identifying the potential therapeutic targets for disease intervention.

LncRNA AFAP1-AS1 promotes M1 polarization of macrophages and osteogenic differentiation of valve interstitial cells

Little is known about the biological functions and underlying mechanisms of long non-coding RNA AFAP1-AS1 in degenerative calcified aortic valve disease (DCAVD). This study aims to explore whether AFAP1-AS1 regulates macrophage polarization in aortic valve calcification. Macrophage polarization and AFAP1-AS1 expression were detected in normal and calcified aortic valves of DCAVD patients. To explore the effect of AFAP1-AS1 on macrophage polarization, gain and loss of function were performed in THP-1 cells, and the percentage of M1 and M2 and the expressions of M1 and M2 markers were analyzed. Meanwhile, osteogenic differentiation was examined in valve interstitial cells (VICs). Compared with normal valves, there were more M1, less M2, and high AFAP1-AS1 expressions in calcified aortic valves, which may indicate a relationship between AFAP1-AS1 and macrophage polarization. AFAP1-AS1 overexpression promoted M1 polarization in lipopolysaccharide (LPS) and interferon gamma (IFN-γ)-treated THP-1 cells but inhibited M2 polarization, as well as augmented VIC osteogenic differentiation. On the contrary, the silence of AFAP1-AS1 could induce macrophage to M2-type and inhibit VIC osteogenic differentiation. These results elucidate that AFAP1-AS1 can promote M1 macrophages polarization to aggravate VIC osteogenic differentiation, playing a role in aortic valve calcification.

Identification of key genes in calcific aortic valve disease via weighted gene co-expression network analysis

Background

Calcific aortic valve disease (CAVD) is the most common subclass of valve heart disease in the elderly population and a primary cause of aortic valve stenosis. However, the underlying mechanisms remain unclear.

Methods

The gene expression profiles of GSE83453, GSE51472, and GSE12644 were analyzed by ‘limma’ and ‘weighted gene co-expression network analysis (WGCNA)’ package in R to identify differentially expressed genes (DEGs) and key modules associated with CAVD, respectively. Then, enrichment analysis was performed based on Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, DisGeNET, and TRRUST database. Protein–protein interaction network was constructed using the overlapped genes of DEGs and key modules, and we identified the top 5 hub genes by mixed character calculation.

Results

We identified the blue and yellow modules as the key modules. Enrichment analysis showed that leukocyte migration, extracellular matrix, and extracellular matrix structural constituent were significantly enriched. SPP1, TNC, SCG2, FAM20A, and CD52 were identified as hub genes, and their expression levels in calcified or normal aortic valve samples were illustrated, respectively.

Conclusions

This study suggested that SPP1, TNC, SCG2, FAM20A, and CD52 might be hub genes associated with CAVD. Further studies are required to elucidate the underlying mechanisms and provide potential therapeutic targets.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-021-00989-w.

Clonal haematopoiesis in patients with degenerative aortic valve stenosis undergoing transcatheter aortic valve implantation

Aims

Clonal haematopoiesis of indeterminate potential (CHIP), defined as the presence of an expanded somatic blood cell clone without other haematological abnormalities, was recently shown to increase with age and is associated with coronary artery disease and calcification. The most commonly mutated CHIP genes, DNMT3A and TET2, were shown to regulate inflammatory potential of circulating leucocytes. The incidence of degenerative calcified aortic valve (AV) stenosis increases with age and correlates with chronic inflammation. We assessed the incidence of CHIP and its association with inflammatory blood cell phenotypes in patients with AV stenosis undergoing transfemoral aortic valve implantation (TAVI).

Methods and results

Targeted amplicon sequencing for DNMT3A and TET2 was performed in 279 patients with severe AV stenosis undergoing TAVI. Somatic DNMT3A- or TET2-CHIP-driver mutations with a VAF ≥ 2% were detected in 93 out of 279 patients (33.3%), with an age-dependent increase in the incidence from 25% (55–69 years) to 52.9% (90–100 years). Patients with DNMT3A- or TET2-CHIP-driver mutations did not differ from patients without such mutations in clinical parameters, concomitant atherosclerotic disease, blood cell counts, inflammatory markers, or procedural characteristics. However, patients with DNMT3A- or TET2-CHIP-driver mutations had a profoundly increased medium-term all-cause mortality following successful TAVI. Differential myeloid and T-cell distributions revealed pro-inflammatory T-cell polarization in DNMT3A-mutation carriers and increased pro-inflammatory non-classical monocytes in TET2-mutation carriers.

Conclusion

This is the first study to show that acquired somatic mutations in the most commonly mutated CHIP-driver genes occur frequently in patients with severe degenerative AV stenosis, are associated with increased pro-inflammatory leucocyte subsets, and confer a profound increase in mortality following successful TAVI.

Predicting the Key Genes Involved in Aortic Valve Calcification Through Integrated Bioinformatics Analysis

Background: Valvular heart disease is obtaining growing attention in the cardiovascular field and it is believed that calcific aortic valve disease (CAVD) is the most common valvular heart disease (VHD) in the world. CAVD does not have a fully effective treatment to delay its progression and the specific molecular mechanism of aortic valve calcification remains unclear.

Materials and Methods: We obtained the gene expression datasets GSE12644 and GSE51472 from the public comprehensive free database GEO. Then, a series of bioinformatics methods, such as GO and KEGG analysis, STING online tool, Cytoscape software, were used to identify differentially expressed genes in CAVD and healthy controls, construct a PPI network, and then identify key genes. In addition, immune infiltration analysis was used via CIBERSORT to observe the expression of various immune cells in CAVD.

Results: A total of 144 differential expression genes were identified in the CAVD samples in comparison with the control samples, including 49 up-regulated genes and 95 down-regulated genes. GO analysis of DEGs were most observably enriched in the immune response, signal transduction, inflammatory response, proteolysis, innate immune response, and apoptotic process. The KEGG analysis revealed that the enrichment of DEGs in CAVD were remarkably observed in the chemokine signaling pathway, cytokine-cytokine receptor interaction, and PI3K-Akt signaling pathway. Chemokines CXCL13, CCL19, CCL8, CXCL8, CXCL16, MMP9, CCL18, CXCL5, VCAM1, and PPBP were identified as the hub genes of CAVD. It was macrophages that accounted for the maximal proportion among these immune cells. The expression of macrophages M0, B cells memory, and Plasma cells were higher in the CAVD valves than in healthy valves, however, the expression of B cells naïve, NK cells activated, and macrophages M2 were lower.

Conclusion: We detected that chemokines CXCL13, CXCL8, CXCL16, and CXCL5, and CCL19, CCL8, and CCL18 are the most important markers of aortic valve disease. The regulatory macrophages M0, plasma cells, B cells memory, B cells naïve, NK cells activated, and macrophages M2 are probably related to the occurrence and the advancement of aortic valve stenosis. These identified chemokines and these immune cells may interact with a subtle adjustment relationship in the development of calcification in CAVD.

Inflammatory and Biomechanical Drivers of Endothelial-Interstitial Interactions in Calcific Aortic Valve Disease

Calcific aortic valve disease is dramatically increasing in global burden, yet no therapy exists outside of prosthetic replacement. The increasing proportion of younger and more active patients mandates alternative therapies. Studies suggest a window of opportunity for biologically based diagnostics and therapeutics to alleviate or delay calcific aortic valve disease progression. Advancement, however, has been hampered by limited understanding of the complex mechanisms driving calcific aortic valve disease initiation and progression towards clinically relevant interventions.

Aortic valve stenosis and cancer: a common and complex association

Introduction. The prevalence of aortic valve stenosis (AS) and malignancy are both high, especially in elderly people and in developed countries. These two conditions frequently coexist and share the same risk factors as atherosclerotic disease.Area covered. The progression of calcified AS may be accelerated by both cardiovascular risk factors and cancer treatments, such as radiotherapy. The standard treatment for symptomatic severe AS is surgical aortic valve replacement; however, in cancer patients, transcatheter implantation may be preferred as they are often at high-risk for cardiac surgery. In patients with AS and cancer, physicians may face difficult treatment decisions.To date, there is limited information on the impact of malignancy on outcomes in patients with severe AS; hence, there is no established treatment policy.Expert Opinion. Treating clinicians must integrate complex information about the severity of valve disease and expected cardiac outcomes with information regarding the cancer prognosis and the need for specific treatment, including surgery. Other comorbidities, age and frailty also contribute to decision-making about whether, when, and how to perform aortic valve replacement.

Telomere Length in Valve Tissue Is Shorter in Individuals With Aortic Stenosis and in Calcified Valve Areas

Background

Short telomere length (TL) is associated with age-related diseases, in particular cardiovascular diseases. However, whether the onset and course of aortic stenosis (AS) is linked to TL in aortic valves remains unknown.

Objectives

To assess telomere dynamics (TL and telomerase activity) in aortic valves and the possible implication of TL in onset and course of AS.

Methods

DNA was extracted from aortic valves obtained from 55 patients (78.2% men; age, 37–79 years), who had undergone replacement surgery due to AS (AS group, n = 32), aortic valve regurgitation and aortic dilation (Non-AS group, n = 23). TL was measured by telomere restriction fragment analysis (TRF) in calcified and non-calcified aortic valve areas. Telomerase activity was evaluated using telomerase repeat amplification protocol (TRAP) in protein extracts from non-calcified and calcified areas of valves obtained from 4 additional patients (50% men; age, 27–70 years).

Results

TL was shorter in calcified aortic valve areas in comparison to non-calcified areas (n = 31, 8.58 ± 0.73 kb vs. 8.12 ± 0.75 kb, p < 0.0001), whereas telomerase activity was not detected in any of those areas. Moreover, patients from AS group displayed shorter telomeres in non-calcified areas than those from the Non-AS group (8.40 ± 0.64 kb vs. 8.85 ± 0.65, p = 0.01).

Conclusions

Short telomeres in aortic valves may participate in the development of AS, while concurrently the calcification process seems to promote further local decrease of TL in calcified areas of valves.

Relationship Between Mitochondrial Structure and Bioenergetics in Pseudoxanthoma elasticum Dermal Fibroblasts

Pseudoxanthoma elasticum (PXE) is a genetic disease considered as a paradigm of ectopic mineralization disorders, being characterized by multisystem clinical manifestations due to progressive calcification of skin, eyes, and the cardiovascular system, resembling an age-related phenotype. Although fibroblasts do not express the pathogenic ABCC6 gene, nevertheless these cells are still under investigation because they regulate connective tissue homeostasis, generating the “arena” where cells and extracellular matrix components can promote pathologic calcification and where activation of pro-osteogenic factors can be associated to pathways involving mitochondrial metabolism. The aim of the present study was to integrate structural and bioenergenetic features to deeply investigate mitochondria from control and from PXE fibroblasts cultured in standard conditions and to explore the role of mitochondria in the development of the PXE fibroblasts’ pathologic phenotype. Proteomic, biochemical, and morphological data provide new evidence that in basal culture conditions (1) the protein profile of PXE mitochondria reveals a number of differentially expressed proteins, suggesting changes in redox balance, oxidative phosphorylation, and calcium homeostasis in addition to modified structure and organization, (2) measure of oxygen consumption indicates that the PXE mitochondria have a low ability to cope with a sudden increased need for ATP via oxidative phosphorylation, (3) mitochondrial membranes are highly polarized in PXE fibroblasts, and this condition contributes to increased reactive oxygen species levels, (4) ultrastructural alterations in PXE mitochondria are associated with functional changes, and (5) PXE fibroblasts exhibit a more abundant, branched, and interconnected mitochondrial network compared to control cells, indicating that fusion prevail over fission events. In summary, the present study demonstrates that mitochondria are modified in PXE fibroblasts. Since mitochondria are key players in the development of the aging process, fibroblasts cultured from aged individuals or aged in vitro are more prone to calcify, and in PXE, calcified tissues remind features of premature aging syndromes; it can be hypothesized that mitochondria represent a common link contributing to the development of ectopic calcification in aging and in diseases. Therefore, ameliorating mitochondrial functions and cell metabolism could open new strategies to positively regulate a number of signaling pathways associated to pathologic calcification.

Label-free optical biomarkers detect early calcific aortic valve disease in a wild-type mouse model

Background

Calcific aortic valve disease (CAVD) pathophysiology is a complex, multistage process, usually diagnosed at advanced stages after significant anatomical and hemodynamic changes in the valve. Early detection of disease progression is thus pivotal in the development of prevention and mitigation strategies. In this study, we developed a diet-based, non-genetically modified mouse model for early CAVD progression, and explored the utility of two-photon excited fluorescence (TPEF) microscopy for early detection of CAVD progression. TPEF imaging provides label-free, non-invasive, quantitative metrics with the potential to correlate with multiple stages of CAVD pathophysiology including calcium deposition, collagen remodeling and osteogenic differentiation.

Methods

Twenty-week old C57BL/6J mice were fed either a control or pro-calcific diet for 16 weeks and monitored via echocardiography, histology, immunohistochemistry, and quantitative polarized light imaging. Additionally, TPEF imaging was used to quantify tissue autofluorescence (A) at 755 nm, 810 nm and 860 nm excitation, to calculate TPEF 755–860 ratio (A_860/525/(A_755/460 + A_860/525)) and TPEF Collagen-Calcium ratio (A_810/525/(A_810/460 + A_810/525)) in the murine valves. In a separate experiment, animals were fed the above diets till 28 weeks to assess for later-stage calcification.

Results

Pro-calcific mice showed evidence of lipid deposition at 4 weeks and calcification at 16 weeks at the valve commissures. The valves of pro-calcific mice also showed positive expression for markers of osteogenic differentiation, myofibroblast activation, proliferation, inflammatory cytokines and collagen remodeling. Pro-calcific mice exhibited lower TPEF autofluorescence ratios, at locations coincident with calcification, that correlated with increased collagen disorganization and positive expression of osteogenic markers. Additionally, locations with lower TPEF autofluorescence ratios at 4 and 16 weeks exhibited increased calcification at later 28-week timepoints.

Conclusions

This study suggests the potential of TPEF autofluorescence metrics to serve as a label-free tool for early detection and monitoring of CAVD pathophysiology.

Correlation Between Plasma Matrix Metalloproteinase-28 Levels and Severity of Calcific Aortic Valve Stenosis

BACKGROUND Calcific aortic valve disease is a common cardiovascular disorder worldwide. This study aimed to investigate the correlation between plasma matrix metalloproteinase-28 (MMP-28) levels and the severity of calcific aortic valve stenosis. MATERIAL AND METHODS Calcific aortic valve stenosis patients who were admitted to the heart center of our hospital between January 2016 and January 2019 to undergo surgery were successively enrolled in this study (55 males and 24 females with an average age of 58.5±9.6). Information on echocardiography, plasma MMP-28 levels, and other clinical data of the patients was retrospectively collected. RESULTS The average plasma MMP-28 level was 2.43±2.22 ng/mL (range, 0.22-8.27 ng/mL). Plasma MMP-28 levels in patients with mild (n=24), moderate (n=31), or severe (n=24) aortic valve stenosis were 0.74 (0.25-2.23), 1.46 (0.50-3.22), and 4.13 (1.54-6.18) ng/mL, respectively, indicating that the patients with severe aortic valve stenosis had significantly higher MMP-28 levels than the patients with moderate or mild aortic valve stenosis (both P<0.01). Regression analysis using the general linear model further revealed that plasma MMP-28 level was correlated with the peak blood flow velocity and mean pressure gradient of the transaortic valve, and the correlations were statistically significant (both P<0.01). CONCLUSIONS MMP-28 level is significantly elevated in severe cases of calcific aortic valve stenosis. Moreover, plasma MMP-28 levels are positively correlated with the mean pressure gradients and peak blood flow velocity of the transaortic valve.

Plasma lipoprotein(a) concentration as an independent predictor of hemodynamic progression of aortic valve stenosis

Calcific aortic valve disease (CAVD) is a common cardiovascular disorder of high social significance. This study aimed to identify independent predictors of hemodynamic progression of CAVD. The relationship between some risk factors, including the rs10455872 polymorphism in the intron 25 of the lipoprotein(a) [Lp(a)] coding region and the plasma Lp(a) concentration, and CAVD severity were prospectively examined in 114 patients. Age (p = 0.023), smoking (p = 0.038), lack of obesity (p = 0.005), triglyceride levels (p = 0.039), and plasma Lp(a) (p < 0.0001) levels were found to be significant determinants of stenosis progression. The rs10455872 polymorphism; however, was not found to be a significant factor for neither the stenosis severity (p = 0.773) nor for plasma Lp(a) levels (p = 0.617). We established a highly significant Lp(a) cut-off concentration (21.2 mg/dL) distinguishing the aortic valve calcification without stenosis from the significant stenosis. Plasma Lp(a) concentration was the only independent predictor of disease progression (p < 0.0001). Moreover, patients with plasma levels of Lp(a) ≥ 21.2 mg/dL were 55 times more likely to develop aortic valve stenosis. We conclude that Lp(a) concentration may prove valuable for more reliable identification of patients at risk of accelerated CAVD development. Future studies are desirable to determine whether plasma Lp(a) levels could be used as a potential biomarker for aortic stenosis progression.

Phenome-wide analyses establish a specific association between aortic valve PALMD expression and calcific aortic valve stenosis

Calcific aortic valve stenosis (CAVS) is a frequent heart disease with significant morbidity and mortality. Recent genomic studies have identified a locus near the gene PALMD (palmdelphin) strongly associated with CAVS. Here, we show that genetically-determined expression of PALMD in the aortic valve is inversely associated with CAVS, with a stronger effect in women, in a meta-analysis of two large cohorts totaling 2359 cases and 350,060 controls. We further demonstrate the specificity of this relationship by showing the absence of other significant association between the genetically-determined expression of PALMD in 9 tissues and 852 phenotypes. Using genome-wide association studies meta-analyses of cardiovascular traits, we identify a significant colocalized positive association between genetically-determined expression of PALMD in four non-cardiac tissues (brain anterior cingulate cortex, esophagus muscularis, tibial nerve and subcutaneous adipose tissue) and atrial fibrillation. The present work further establishes PALMD as a promising molecular target for CAVS.

Zhonglin Li et al. perform phenome-wide analyses to explore the genetic association between the locus near PALMD and calcific aortic valve stenosis (CAVS). Using previously reported aortic valve expression data and genotypes from large cohorts, they find a strong and specific association between genetically-determined PALMD expression in the aortic valve and CAVS as well as a novel association with atrial fibrillation in non-cardiac tissues.

Interaction of Autotaxin With Lipoprotein(a) in Patients With Calcific Aortic Valve Stenosis

Our objectives were to determine whether autotaxin (ATX) is transported by lipoprotein(a) [Lp(a)] in human plasma and if could be used as a biomarker of calcific aortic valve stenosis (CAVS). We first found that ATX activity was higher in Lp(a) compared to low-density lipoprotein fractions in isolated fractions of 10 healthy participants. We developed a specific assay to measure ATX-Lp(a) in 88 patients with CAVS and 144 controls without CAVS. In a multivariable model corrected for CAVS risk factors, ATX-Lp(a) was associated with CAVS (p = 0.003). We concluded that ATX is preferentially transported by Lp(a) and might represent a novel biomarker for CAVS.

Antibody microarray analysis of serum inflammatory cytokines in patients with calcific aortic valve disease

Background

Calcific aortic valve disease (CAVD) is a slowly progressive pathologic process associated with significant morbidity and mortality, CAVD is the most common valve heart disease in the elderly and a leading cause of aortic valve stenosis. Multiple steps characterize the process: inflammation, cell apoptosis, lipid deposition, renin-angiotensin system activation, extracellular matrix remodeling, and bone formation. This paper focuses on detecting and analyzing the expression of serum inflammatory factors in CAVD by antibody microarray techniques.

Methods

In this study, a total of 258 patients were included at Tianjin Chest Hospital between January 2017 and December 2018, subjects were divided into three groups: control, coronary artery disease (CAD), and CAVD. Blood samples were collected, and adipokine/cytokine/chemokine serum profiles were measured by antibody arrays.

Results

These data suggest that B-Lymphocyte Chemoattractant (BLC), Interleukin (IL)-12p40, monokine inducible by γ interferon (MIG), and Macrophage inflammatory protein (MIP)-1delta were significantly increased in CAVD compared to control or CAD. Furthermore, Real-time quantified PCR, Western blot assay, and Flow cytometer detection showed that these four cytokines/chemokines were from peripheral blood mononuclear cells.

Conclusions

These findings suggest that BLC, IL-12p40, MIG, and MIP-1delta can be used as a marker to assess CAVD, which could have significant clinical implications.

The impact of altered mechanobiology on aortic valve pathophysiology

Calcific aortic valve disease (CAVD) is the most prevalent valvulopathy worldwide. Until recently, CAVD was viewed as a passive, degenerative process and an inevitable consequence of aging. Recent improvements in disease modeling, imaging, and analysis have greatly enhanced our understanding of CAVD. The aortic valve and its constituent cells are subjected to extreme changes in mechanical forces, so it follows that any changes in the underlying mechanobiology of the valve and its cells would have dire effects on function. Further, the mechanobiology of the aortic valve is intimately intertwined with numerous molecular pathways, with signal transduction between these aspects afforded by the dynamic plasma membrane. Changes to the plasma membrane itself, its regulation of the extracellular matrix, or the relay of signals into or out of the cell would negatively impact cell and tissue function.

PURPOSE OF REVIEW

This review seeks to detail past and current published reports related to the mechanobiology of the aortic valve with a special emphasis on the implications of altered mechanobiology in the context of calcific aortic valve disease.

RECENT FINDINGS

Investigations characterizing membrane composition and dynamics have provided new insights into the earliest stages of calcific aortic valve disease. Recent studies have suggested that the activation or suppression of key pathways contribute to disease progression but may also offer therapeutic targets.

SUMMARY

This review highlights the critical involvement of mechanobiology and membrane dynamics in normal aortic valve physiology as well as valve pathology.

The Ryanodine Receptor Contributes to the Lysophosphatidylcholine-Induced Mineralization in Valvular Interstitial Cells

PURPOSE

Fibrocalcific aortic valve disease (CAVD) is caused by the deposition of calcific nodules in the aortic valve leaflets, resulting in progressive loss of function that ultimately requires surgical intervention. This process is actively mediated by the resident valvular interstitial cells (VICs), which, in response to oxidized lipids, transition from a quiescent to an osteoblast-like state. The purpose of this study was to examine if the ryanodine receptor, an intracellular calcium channel, could be therapeutically targeted to prevent this phenotypic conversion.

METHODS

The expression of the ryanodine receptor in porcine aortic VICs was characterized by qRT-PCR and immunofluorescence. Next, the VICs were exposed to lysophosphatidylcholine, an oxidized lipid commonly found in low-density lipoprotein, while the activity of the ryanodine receptor was modulated with ryanodine. The cultures were analyzed for markers of cellular mineralization, alkaline phosphatase activity, proliferation, and apoptosis.

RESULTS

Porcine aortic VICs predominantly express isoform 3 of the ryanodine receptors, and this protein mediates the cellular response to LPC. Exposure to LPC caused elevated intracellular calcium concentration in VICs, raised levels of alkaline phosphatase activity, and increased calcific nodule formation, but these changes were reversed when the activity of the ryanodine receptor was blocked.

CONCLUSIONS

Our findings suggest blocking the activity of the ryanodine receptor can attenuate the valvular mineralization caused by LPC. We conclude that oxidized lipids, such as LPC, play an important role in the development and progression of CAVD and that the ryanodine receptor is a promising target for pharmacological intervention.

Differences in mineral composition and morphology between men and women in aortic valve calcification

Aortic valve calcification leads to the deposition of calcium phosphate minerals in the extracellular matrix of the aortic valve leaflets. The mineral deposits can severely narrow the opening of the aortic valve, leading to aortic stenosis. There are no therapies to halt or slow down disease progression and the mechanisms governing aortic valve calcification are still poorly understood. Recently, several studies have shown that for the same aortic stenosis severity, women present significantly lower calcification loads than men. The cause of this sex-related difference is unknown. To understand this difference, we analyzed mineral deposits from surgically excised calcified human aortic valves with different material characterization techniques. We find profound differences in mineral composition and morphology between sexes, which strongly suggest that minerals form slower in women than in men and follow a different mineralization pathway. This finding paves the way for new approaches specifically geared towards men or women in the diagnosis and treatment of aortic valve calcification. STATEMENT OF SIGNIFICANCE: Aortic valve calcification is a health disorder with increasing prevalence and high morbidity and mortality. Currently there is no approved effective treatment; the only available therapeutic option is invasive valve replacement, to which not all patients are suited. The main reason for such lack of treatment options is our lack of understanding of the calcification mechanism. In this study, we show profound differences in mineral composition and morphology between sexes, suggesting that aortic valve calcification follows different mineralization pathways in men and women. These findings pave the way for new approaches specifically geared towards men or women in the diagnosis and treatment of aortic valve calcification.

Durability of transcatheter aortic valve implantation: A translational review

Until recently, transcatheter aortic valve implantation was restricted to high-risk and inoperable patients. The updated 2017 European Society of Cardiology Guidelines has widened the indication to include intermediate-risk patients, based on two recently published trials (PARTNER 2 and SURTAVI). Moreover, two other recent trials (PARTNER 3 and EVOLUT LOW RISK) have demonstrated similar results with transcatheter aortic valve implantation in low-risk patients. Thus, extension of transcatheter aortic valve implantation to younger patients, who are currently treated by surgical aortic valve replacement, raises the crucial question of bioprosthesis durability. In this translational review, we propose to produce a state-of-the-art overview of the durability of transcatheter aortic valve implantation by integrating knowledge of the basic science of bioprosthesis degeneration (pathophysiology and biomarkers). After summarising the new definition of structural valve deterioration, we will present what is known about the pathophysiology of aortic stenosis and bioprosthesis degeneration. Next, we will consider how to identify a population at risk of early degeneration, and how basic science with the help of biomarkers could identify and predict structural valve deterioration. Finally, we will present data on the differences in durability of transcatheter aortic valve implantation compared with surgical aortic valve replacement.

The natural compound andrographolide inhibits human aortic valve interstitial cell calcification via the NF-kappa B/Akt/ERK pathway

Calcific aortic valve disease (CAVD) is caused by valve interstitial cells (VICs) initiating the thickening and calcification of valve leaflets. The present study aimed to investigate whether andrographolide (AGP) could attenuate the calcification of human valve interstitial cells (hVICs). hVICs stimulated by osteoblastic medium (OM) were treated with or without AGP. RNA sequencing was utilized to investigate changes in gene expression. Cell growth and calcification of hVICs were assessed using a CCK8 assay and Alizarin Red S staining, respectively. The expression of the two calcification-related markers, RUNX2 and ALP, were quantified by qRT-PCR, Western blotting, and immunofluorescent staining. The results indicate that hVICs treated with OM plus AGP exhibited decreased Alizarin Red S staining compared with cells treated with OM only in addition to down-regulation of ALP and RUNX2. Mappings of differentially expressed genes (DEGs) in different groups using Venn diagrams during analysis of gene expression profiles, 653 common DEGs were identified that displayed different biological functions and signaling pathways after treatment with AGP. RELA, a core factor of the NF-κB pathway was inhibited by AGP in addition to phosphorylation of AKT and ERK1/2. Thus, AGP attenuated calcification of hVICs. These results demonstrate that AGP, a promising natural product, can attenuate the process of CAVD.

LncRNA AFAP1-AS1 promotes osteoblast differentiation of human aortic valve interstitial cells through regulating miR-155/SMAD5 axis

AIM

Degenerative calcific aortic valve disease (DCAVD) is a common valve disease characterized by massive calcium deposits in the aortic valve. Osteoblast differentiation of valve interstitial cells (VICs) is responsible for the formation of calcific nodules. This study aims to explore the function and underlying mechanism of long non-coding RNA (lncRNA) AFAP1-AS1 (actin filament-associated protein 1 antisense RNA 1) in the pathogenesis of DCAVD.

METHODS

AFAP1-AS1, miR-155 and mRNA levels were detected by qRT-PCR. Protein levels were measured by Western blot. Calcification deposition was examined by Alizarin Red staining. The interaction between AFAP1-AS1 and miR-155, as well as miR-155 and SMAD5 was evaluated using luciferase reporter assay.

RESULTS

AFAP1-AS1 expression was increased both in calcified aortic valves from DCAVD patients and after osteogenic induction in human VICs. Furthermore, AFAP1-AS1 overexpression promoted osteogenic differentiation of VICs, whereas AFAP1-AS1 knockdown inhibited osteogenic differentiation. Mechanistically, AFAP1-AS1 acted as a sponge for miR-155 to elevate SMAD5 expression. Further functional assays revealed that miR-155 mimic and SMAD5 silencing effectively reversed AFAP1-AS1-promoted osteogenic differentiation of VICs.

CONCLUSION

Collectively, AFAP1-AS1 promotes osteogenic differentiation of VICs, at least in part, by sponging miR-155 to upregulate SMAD5. This study sheds new light on lncRNA-directed therapeutics in DCAVD.

The Role of the Renin-Angiotensin System and Vitamin D in Keloid Disorder-A Review

Keloid disorder (KD) is a fibroproliferative condition characterized by excessive dermal collagen deposition in response to wounding and/or inflammation of the skin. Despite intensive research, treatment for KD remains empirical and unsatisfactory. Activation of the renin-angiotensin system (RAS) leads to fibrosis in various organs through its direct effect and the resultant hypertension, and activation of the immune system. The observation of an increased incidence of KD in dark-skinned individuals who are predisposed to vitamin D deficiency (VDD) and hypertension, and the association of KD with hypertension and VDD, all of which are associated with an elevated activity of the RAS, provides clues to the pathogenesis of KD. There is increasing evidence implicating embryonic-like stem (ESC) cells that express ESC markers within keloid-associated lymphoid tissues (KALTs) in keloid lesions. These primitive cells express components of the RAS, cathepsins B, D, and G that constitute bypass loops of the RAS, and vitamin D receptor (VDR). This suggests that the RAS directly, and through signaling pathways that converge on the RAS, including VDR-mediated mechanisms and the immune system, may play a critical role in regulating the primitive population within the KALTs. This review discusses the role of the RAS, its relationship with hypertension, vitamin D, VDR, VDD, and the immune system that provide a microenvironmental niche in regulating the ESC-like cells within the KALTs. These ESC-like cells may be a novel therapeutic target for the treatment of this enigmatic and challenging condition, by modulating the RAS using inhibitors of the RAS and its bypass loops and convergent signaling pathways.

DNA methylation of a PLPP3 MIR transposon-based enhancer promotes an osteogenic programme in calcific aortic valve disease

Aims

Calcific aortic valve disease (CAVD) is characterized by the osteogenic transition of valve interstitial cells (VICs). In CAVD, lysophosphatidic acid (LysoPA), a lipid mediator with potent osteogenic activity, is produced in the aortic valve (AV) and is degraded by membrane-associated phospholipid phosphatases (PLPPs). We thus hypothesized that a dysregulation of PLPPs could participate to the osteogenic reprograming of VICs during CAVD.

Methods and results

The expression of PLPPs was examined in human control and mineralized AVs and comprehensive analyses were performed to document the gene regulation and impact of PLPPs on the osteogenic transition of VICs. We found that PLPP3 gene and enzymatic activity were downregulated in mineralized AVs. Multidimensional gene profiling in 21 human AVs showed that expression of PLPP3 was inversely correlated with the level of 5-methylcytosine (5meC) located in an intronic mammalian interspersed repeat (MIR) element. Bisulphite pyrosequencing in a larger series of 67 AVs confirmed that 5meC in intron 1 was increased by 2.2-fold in CAVD compared with control AVs. In isolated cells, epigenome editing with clustered regularly interspersed short palindromic repeats-Cas9 system containing a deficient Cas9 fused with DNA methyltransferase (dCas9-DNMT) was used to increase 5meC in the intronic enhancer and showed that it reduced significantly the expression of PLPP3. Knockdown experiments showed that lower expression of PLPP3 in VICs promotes an osteogenic programme.

Conclusions

DNA methylation of a MIR-based enhancer downregulates the expression of PLPP3 and promotes the mineralization of the AV.

Expression levels of paraoxonase-1 in aortic valve tissue are associated with the progression of calcific aortic valve stenosis

Background

Paraoxonase-1 (PON1) participates in several vital steps of lipid metabolism, which is associated with calcific aortic valve stenosis (CAVS). Although a few studies have suggested that PON1 in blood could inhibit aortic valve calcification, they did not provide detailed descriptions. In this study, we hypothesized that PON1 is expressed in the aortic valve and that the PON1 level is related to the severity of CAVS.

Methods

A total of 118 consecutive patients with CAVS were enrolled in the study; 35 individuals without aortic valve calcification were included in the control group. Aortic valve tissue was obtained from postoperative pathologic specimens. PON1 was detected qualitatively using immunohistochemistry and quantitatively using an enzyme-linked immunosorbent assay. The severity of aortic stenosis was evaluated using echocardiography.

Results

We detected PON1 in the aortic valve and noticed that the PON1 level was significantly lower in the case group than in the control group (P<0.001). Furthermore, we found no significant difference between the mild and moderate stenosis groups (P=0.395). However, the PON1 levels were obviously higher in both the mild and moderate stenosis groups than in the severe stenosis group (both P<0.001). We also detected a significant negative correlation between PON1 level and the maximum aortic valve gradient in the case group.

Conclusions

We detected PON1 in the aortic valve for the first time, and our results suggest that the PON1 level in aortic valve tissue decreases with increasing severity of aortic valve stenosis.

MicroRNA-638 inhibits human aortic valve interstitial cell calcification by targeting Sp7

Calcific aortic valve disease (CAVD) is a complex heart valve disease involving a wide range of pathological changes. Emerging evidence indicates that osteogenic differentiation of human aortic valve interstitial cells (hAVICs) plays a key role in valve calcification. In this study, we aimed to investigate the function of miR-638 in hAVICs osteogenesis. Both miRNA microarray assay and qRT-PCR results demonstrating miR-638 was obviously up-regulated in calcific aortic valves compared with non-calcific valves. We also proved that miR-638 was significantly up-regulated during hAVICs osteogenic differentiation. Overexpression of miR-638 suppressed osteogenic differentiation of hAVICs in vitro, whereas down-regulation of miR-638 enhance the process. Target prediction analysis and dual-luciferase reporter assay confirmed that Sp7 transcription factor (Sp7) was a direct target of miR-638. Furthermore, knockdown of Sp7 inhibited osteogenic differentiation of hAVICs, which is similar to the results observed in up-regulation miR-638. Our data indicated that miR-638 plays an inhibitory role in hAVICs osteogenic differentiation, which may act by targeting Sp7. MiR-638 may be a potential therapeutic target for CAVD.

Oxidized HDL, as a Novel Biomarker for Calcific Aortic Valve Disease, Promotes the Calcification of Aortic Valve Interstitial Cells

Calcific aortic valve disease (CAVD) is characterized by progressive mineralization of the aortic valve. Lipid infiltration and oxidative stress are the driving forces for the initiation and development of this disease. However, it remains unknown whether oxidized high-density lipoprotein (ox-HDL) plays a role in the mineralization of aortic valve interstitial cells (AVICs). Serum ox-HDL levels were determined in 168 severe CAVD patients and 168 age- and gender-matched non-CAVD controls. Results showed that ox-HDL concentrations were significantly increased in CAVD compared with the control group (131.52 ± 30.96 ng/mL vs. 112.58 ± 32.20 ng/mL, P < 0.001) and were correlated with CAVD severity. Multivariable logistic regression revealed that ox-HDL levels were independently associated with CAVD after adjusting for the incidence of coronary artery disease (CAD) (odds ratio 1.019, 95% CI 1.012-1.027, P < 0.001) or atherosclerotic risk factors (odds ratio 1.027, 95% CI 1.017-1.037, P < 0.001). Chronic ox-HDL stimulation of AVICs increased alkaline phosphatase activity (ALP) and calcium deposits in AVICs in vitro. Mechanistic studies further showed that ox-HDL upregulated several osteogenic factors, including BMP-2, Runx2, and Msx2 expressions in AVICs. This is the first study to demonstrate a relationship between increased ox-HDL concentration and CAVD incidence.

Development of calcific aortic valve disease: Do we know enough for new clinical trials?

Calcific aortic valve disease (CAVD), previously thought to represent a passive degeneration of the valvular extracellular matrix (VECM), is now regarded as an intricate multistage disorder with sequential yet intertangled and interacting underlying processes. Endothelial dysfunction and injury, initiated by disturbed blood flow and metabolic disorders, lead to the deposition of low-density lipoprotein cholesterol in the VECM further provoking macrophage infiltration, oxidative stress, and release of pro-inflammatory cytokines. Such changes in the valvular homeostasis induce differentiation of normally quiescent valvular interstitial cells (VICs) into synthetically active myofibroblasts producing excessive quantities of the VECM and proteins responsible for its remodeling. As a result of constantly ongoing degradation and re-deposition, VECM becomes disorganised and rigid, additionally potentiating myofibroblastic differentiation of VICs and worsening adaptation of the valve to the blood flow. Moreover, disrupted and excessively vascularised VECM is susceptible to the dystrophic calcification caused by calcium and phosphate precipitating on damaged collagen fibers and concurrently accompanied by osteogenic differentiation of VICs. Being combined, passive calcification and biomineralisation synergistically induce ossification of the aortic valve ultimately resulting in its mechanical incompetence requiring surgical replacement. Unfortunately, multiple attempts have failed to find an efficient conservative treatment of CAVD; however, therapeutic regimens and clinical settings have also been far from the optimal. In this review, we focused on interactions and transitions between aforementioned mechanisms demarcating ascending stages of CAVD, suggesting a predisposing condition (bicuspid aortic valve) and drug combination (lipid-lowering drugs combined with angiotensin II antagonists and cytokine inhibitors) for the further testing in both preclinical and clinical trials.

Adaptive immune cells in calcific aortic valve disease

Calcific aortic valve disease (CAVD) is highly prevalent and has no pharmaceutical treatment. Surgical replacement of the aortic valve has proved effective in advanced disease but is costly, time limited, and in many cases not optimal for elderly patients. This has driven an increasing interest in noninvasive therapies for patients with CAVD. Adaptive immune cell signaling in the aortic valve has shown potential as a target for such a therapy. Up to 15% of cells in the healthy aortic valve are hematopoietic in origin, and these cells, which include macrophages, T lymphocytes, and B lymphocytes, are increased further in calcified specimens. Additionally, cytokine signaling has been shown to play a causative role in aortic valve calcification both in vitro and in vivo. This review summarizes the physiological presence of hematopoietic cells in the valve, innate and adaptive immune cell infiltration in disease states, and the cytokine signaling pathways that play a significant role in CAVD pathophysiology and may prove to be pharmaceutical targets for this disease in the near future.

Noncoding RNAs in Calcific Aortic Valve Disease: A Review of Recent Studies

Calcific aortic valve disease (CAVD) is the most common heart valve disorder in human populations. Nevertheless, there are presently no effective means for its prevention and treatment. It is therefore critical to comprehensively define key mechanisms of the disease. A major focus of cardiovascular research has been characterization of how regulation of gene expression maintains healthy physiologic status of the component tissues of the system and how derangements of gene regulation may become pathological. Recently, substantial evidence has emerged that noncoding RNAs, which are an enormous and versatile class of regulatory elements, such as microRNAs and long noncoding RNAs, have roles in onset and prognosis of CAVD. Authors of the present report have therefore here provided a summary of the current understanding of contributions made by noncoding RNAs major features of CAVD. It is anticipated that this article will serve as a valuable guide to research strategy in this field and may additionally provide both researchers and clinicians with an expanded range of CAVD-associated biomarkers.

Brief report - Telomere length is a poor biomarker to predict 1-year mortality or cardiovascular comorbidity in patients with transcatheter aortic valve replacement

Background

Transcatheter aortic valve replacement (TAVR) is a therapeutic option for patients with aortic valve stenosis at increased surgical risk. Telomeres are an established marker for cellular senescence and have served to evaluate cardiovascular diseases including severe aortic valve stenosis. In our study, we hypothesized that telomere length may be a predictor for outcome and associated with comorbidities in patients with TAVR.

Methods and results

We analyzed leucocyte telomere length from 155 patients who underwent TAVR and correlated the results with 1-year mortality and severe comorbidities. The cohort was subdivided into 3 groups according to telomere length. Although a trend for a positive correlation of telomere length with a lower EuroSCORE could be found, telomere length was not associated with survival, aortic valve opening area or cardiovascular comorbidities (peripheral, coronary or cerebrovascular disease). Interestingly, long telomeres were significantly correlated to a reduced left ventricular ejection fraction (LVEF).

Conclusion

In elderly patients with severe aortic valve stenosis, leucocyte telomere length did not predict post-procedural survival. The correlation between long telomere length and reduced LVEF in these patients deserves further attention.

Autotaxin and Lipoprotein Metabolism in Calcific Aortic Valve Disease

Calcific aortic valve disease (CAVD) is a complex trait disorder characterized by calcific remodeling of leaflets. Genome-wide association (GWA) study and Mendelian randomization (MR) have highlighted that LPA, which encodes for apolipoprotein(a) [apo(a)], is causally associated with CAVD. Apo(a) is the protein component of Lp(a), a LDL-like particle, which transports oxidized phospholipids (OxPLs). Autotaxin (ATX), which is encoded by ENPP2, is a member of the ecto-nucleotidase family of enzymes, which is, however, a lysophospholipase. As such, ATX converts phospholipids into lysophosphatidic acid (LysoPA), a metabolite with potent and diverse biological properties. Studies have recently underlined that ATX is enriched in the Lp(a) lipid fraction. Functional experiments and data obtained in mouse models suggest that ATX mediates inflammation and mineralization of the aortic valve. Recent findings also indicate that epigenetically-driven processes lower the expression of phospholipid phosphatase 3 (PLPP3) and increased LysoPA signaling and inflammation in the aortic valve during CAVD. These recent data thus provide novel insights about how lipoproteins mediate the development of CAVD. Herein, we review the implication of lipoproteins in CAVD and examine the role of ATX in promoting the osteogenic transition of valve interstitial cells (VICs).

Predictive Roles of Neutrophil-to-Lymphocyte Ratio and C-Reactive Protein in Patients with Calcific Aortic Valve Disease

The neutrophil-to-lymphocyte ratio (NLR) and C-reactive protein (CRP) are emerging indirect blood markers to roughly reflect the inflammation level in our body while some pathological changes occurring in aortic valve tissue. Few recent studies demonstrated that NLR is related to calcific aortic valve disease (CAVD). However, the extent of the relationship between them and the impact of CRP on CAVD are not clear. This study aimed to investigate the diagnostic influence and surgical predictive effect of NLR and CRP on CAVD.A total of 278 consecutive patients with CAVD (123 patients with bicuspid aortic valve and others with tricuspid aortic valve) and 108 healthy individuals who were included in the control group were enrolled in the study. The NLR was calculated from the complete blood count, and the CRP was measured from peripheral blood samples. Echocardiography was used to evaluate the severity of aortic stenosis. Intraoperation/postoperation indicators were collected in 166 patients from the total consecutive patients who underwent aortic valve replacement (AVR) alone.Significantly higher NLR was measured in both the BAV group (1.96 ± 0.78 versus 0.97 ± 0.15, P < 0.001) and the TAV group (2.51 ± 2.03 versus 0.97 ± 0.15, P < 0.001) compared with the control group. Moreover, the NLR level was significantly higher (P < 0.001) and the CRP level was significantly lower (P = 0.007) of the TAV group than that of the BAV group; a significant positive correlation between the NLR and the maximum gradient of aortic valve was detected. Furthermore, there was a moderate correlation between the NLR and the postoperative mechanical ventilation time.Our results indicated that the NLR and CRP were novel and useful predictive factors in patients with CAVD, and these two potential factors have guiding significance for the prediction of different pathological typing (BAV or TAV). Higher NLR level will not extend the cardiopulmonary bypass time (CPB); however, it will prolong the operation time and the postoperative mechanical ventilation time.

Recent Advances on Relationship Between Inorganic Phosphate and Pathologic Calcification: Is Calcification After Breast Augmentation with Fat Grafting Correlated with Locally Increased Concentration of Inorganic Phosphate?

BACKGROUND

Pathologic calcification has frequently occurred after breast augmentation with fat grafting as well as other conditions such as breast cancer, trauma, myocardial infarction, arteriosclerosis and even after reduction mammoplasty. Inorganic phosphate, correlated with fat metabolism, is an important factor that induces pathologic calcification such as vascular calcification.

METHODS

A literature search was conducted using PubMed with the keywords: calcification, inorganic phosphate, fat. Studies related to the process of pathologic calcification, correlation between inorganic phosphate and pathologic calcification, between inorganic phosphate and fat metabolism in pathologic calcification were collected.

RESULTS

Various mechanisms were referred to in pathologic calcification among which inorganic phosphate played an important role. Inorganic phosphate could be liberated, under the effect of various enzymes, in the process of fat metabolism. The authors hypothesized that a large-scale necrotizing zone, which could occur in fat grafting with large amounts per cannula, might provide a high-phosphate environment which might contribute to differentiation of surrounding cells such as stem cells or regenerated vessel cells into osteoblast-like cells that induce pathologic calcification.

CONCLUSION

Inorganic phosphate, which was correlated with fat metabolism, played a significant role in pathologic calcification. We firstly hypothesize that calcification after fat grafting may be related to locally increasing concentrations of phosphate in a necrotizing zone. Further research should be conducted to verify this hypothesis.

LEVEL OF EVIDENCE V

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