Identification of Circulating Inflammatory Proteins Associated with Calcific Aortic Valve Stenosis by Multiplex Analysis

Calcific aortic valve stenosis (CAVS) is characterized by increasing inflammation and progressive calcification in the aortic valve leaflets and is a major cause of death in the aging population. This study aimed to identify the inflammatory proteins involved in CAVS and provide potential therapeutic targets. We investigated the observational and causal associations of 92 inflammatory proteins, which were measured using affinity-based proteomic assays. Firstly, the case-control cohort identified differential proteins associated with the occurrence and progression of CAVS. Subsequently, we delved into exploring the causal impacts of these associated proteins through Mendelian randomization. This involved utilizing genetic instruments derived from cis-protein quantitative loci identified in genome-wide association studies, encompassing a cohort of over 400,000 individuals. Finally, we investigated the gene transcription and protein expression levels of inflammatory proteins by single-cell and immunohistochemistry analysis. Multivariate logistic regression and spearman's correlation analysis showed that five proteins showed a significant positive correlation with disease severity. Mendelian randomization showed that elevated levels of two proteins, namely, matrix metallopeptidase-1 (MMP1) and sirtuin 2 (SIRT2), were associated with an increased risk of CAVS. Immunohistochemistry and single-cell transcriptomes showed that expression levels of MMP1 and SIRT2 at the tissue and cell levels were significantly higher in calcified valves than in non-calcified control valves. These findings indicate that MMP1 and SIRT2 are causally related to CAVS and open up the possibility for identifying novel therapeutic targets.

Treatment of Lp(a): Is It the Future or Are We Ready Today?

PURPOSE OF REVIEW

The goal of this review is to present the pharmacodynamic effectiveness as well as the clinical efficacy and safety of investigational antisense oligonucleotides (ASOs) and small interference RNAs (siRNAs) drugs that specifically target lipoprotein(a) (Lp(a)). The review will discuss whether the existing lipid-lowering therapies are adequate to treat high Lp(a) levels or whether it is necessary to use the emerging new therapeutic approaches which are based on the current RNA technologies.

RECENT FINDINGS

Lipoprotein(a) (Lp(a)) is a causal risk factor for atherosclerotic cardiovascular disease (ASCVD), independent of other conventional risk factors. High Lp(a) levels are also independently associated with an increased risk of aortic stenosis progression rate. Plasma Lp(a) levels are primarily genetically determined by variation in the LPA gene coding for apo(a). All secondary prevention trials have demonstrated that the existing hypolipidemic therapies are not adequate to reduce Lp(a) levels to such an extent that could lead to a substantial reduction of ASCVD risk. This has led to the development of new drugs that target the mRNA transcript of LPA and efficiently inhibit Lp(a) synthesis leading to potent Lp(a) reduction. These new drugs are the ASO pelacarsen and the siRNAs olpasiran and SLN360. Recent pharmacodynamic studies showed that all these drugs potently reduce Lp(a) up to 98%, in a dose-dependent manner. Ongoing clinical trials will determine the Lp(a)-lowering efficacy, tolerability, and safety of these drugs as well as their potential effectiveness in reducing the ASCVD risk attributed to high plasma Lp(a) levels. We are not ready today to significantly reduce plasma Lp(a). Emerging therapies potently decrease Lp(a) and ongoing clinical trials will determine their effectiveness in reducing ASCVD risk in subjects with high Lp(a) levels.

Impact of C-reactive protein levels on lipoprotein(a)-associated aortic stenosis incidence and progression

Aims

Elevated lipoprotein(a) [Lp(a)] levels are associated with the risk of coronary artery disease (CAD) and calcific aortic valve stenosis (CAVS). Observational studies revealed that Lp(a) and C-reactive protein (CRP) levels, a biomarker of systemic inflammation, may jointly predict CAD risk. Whether Lp(a) and CRP levels also jointly predict CAVS incidence and progression is unknown.

Methods and results

We investigated the association of Lp(a) with CAVS according to CRP levels in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk study (n = 18 226, 406 incident cases) and the UK Biobank (n = 438 260, 4582 incident cases), as well as in the ASTRONOMER study (n = 220), which assessed the haemodynamic progression rate of pre-existing mild-to-moderate aortic stenosis. In EPIC-Norfolk, in comparison to individuals with low Lp(a) levels (<50 mg/dL) and low CRP levels (<2.0 mg/L), those with elevated Lp(a) (>50 mg/dL) and low CRP levels (<2.0 mg/L) and those with elevated Lp(a) (>50 mg/dL) and elevated CRP levels (>2.0 mg/L) had a higher CAVS risk [hazard ratio (HR) = 1.86 (95% confidence intervals, 1.30-2.67) and 2.08 (1.44-2.99), respectively]. A comparable predictive value of Lp(a) in patients with vs. without elevated CRP levels was also noted in the UK Biobank. In ASTRONOMER, CAVS progression was comparable in patients with elevated Lp(a) levels with or without elevated CRP levels.

Conclusion

Lp(a) predicts the incidence and possibly progression of CAVS regardless of plasma CRP levels. Lowering Lp(a) levels may warrant further investigation in the prevention and treatment of CAVS, regardless of systemic inflammation.

Lipoprotein(a) and cardiovascular and valvular diseases: A genetic epidemiological perspective

Rates of atherosclerotic cardiovascular diseases (CVD) in the Western world have spectacularly decreased over the past 50 years. However, a substantial proportion of high-risk patients still develop heart attacks, strokes and valvular heart diseases despite benefiting from state-of-the-art treatments including lipid-lowering therapies. Over the past 10-15 years, it has become increasingly clear that Lipoprotein(a) (Lp[a]) is a critical component of this so-called residual risk. Genetic association studies revealed that Lp(a) is robustly, independently and causally associated with a broad range of cardiovascular and valvular heart diseases. Up to 1 billion people around the globe may have an Lp(a) level that places them in a high-risk category. Lp(a) is strongly associated with calcific aortic valve stenosis (CAVS), coronary artery disease (CAD), peripheral arterial disease (PAD) and to a lesser extent with ischemic stroke (IS) and heart failure (HF). Because of this strong association with cardiovascular and valvular heart diseases, Lp(a) even emerged as one of the most important genetic determinants of human lifespan and healthspan. Here, we review the evidence from the largest and most informative genetic association studies and prospective studies that have investigated the association between Lp(a) and human lifespan, healthspan, CVD, CAVS and non-cardiovascular diseases. We present Lp(a) threshold values that may be clinically relevant and identify other cardiovascular risk factors that may modulate the absolute risk of CVD in individuals with high Lp(a) levels. Finally, we identify key clinical and research questions that require further investigation to eventually and optimally reduce CVD risk in patients with high Lp(a) levels.

Calcific aortic valve stenosis - comparison of inflammatory lesions in the left, right, and non-coronary cusp

BACKGROUND

Calcific aortic valve stenosis (CAVS) is the most frequent acquired heart valve disease in the developed world and the most common cause of heart valve replacement, particularly in older adults. It is considered a form of atherosclerosis and, like the latter, of inflammatory pathogenesis.

METHODS

The incidence and severity of features of chronic inflammation (vascularization, cellular infiltration, bone metaplasia, calcification) in surgically resected semilunar cusps of a tricuspid aortic valve in 100 patients with CAVS were assessed. A novel method of placing metal clips during the operation by the surgeon to distinguish individual cusps was implemented, allowing the pathologist to associate lesions to particular cusps. The findings were evaluated statistically.

RESULTS

The median age of the cohort was 73 years. There was a male predominance of 3.5:1. Almost all the patients had a medical history of risk factors - hypertension (92x), diabetes (51x), and dyslipidaemia (85x). Statistical evaluation of the pathological findings showed that the left cusp was least affected by calcification, vascularization, and chronic inflammation, compared to both the right and non-coronary cusps. On the other hand, the left cusp was the most common site of bone metaplasia. The reason for these differences is unknown. We speculate about mechanobiological effects of abnormal hemodynamics.

CONCLUSIONS

Chronic inflammation plays a significant role in pathogenesis of CAVS. Distinguishing the resected aortic valve cusps by placing metal clips is a useful method to study potential differences (topography) in the pathology of individual cusps.

Therapeutic inhibition of microRNA-34a ameliorates aortic valve calcification via modulation of Notch1-Runx2 signalling

AIMS

Calcific aortic valve stenosis (CAVS) is the most common valvular heart disease and is increased with elderly population. However, effective drug therapy has not been established yet. This study aimed to investigate the role of microRNAs (miRs) in the development of CAVS.

METHODS AND RESULTS

We measured the expression of 10 miRs, which were reportedly involved in calcification by using human aortic valve tissue from patients who underwent aortic valve replacement with CAVS or aortic regurgitation (AR) and porcine aortic valve interstitial cells (AVICs) after treatment with osteogenic induction medium. We investigated whether a specific miR-inhibitor can suppress aortic valve calcification in wire injury CAVS mice model. Expression of miR-23a, miR-34a, miR-34c, miR-133a, miR-146a, and miR-155 was increased, and expression of miR-27a and miR-204 was decreased in valve tissues from CAVS compared with those from AR. Expression of Notch1 was decreased, and expression of Runt-related transcription factor 2 (Runx2) was increased in patients with CAVS compared with those with AR. We selected miR-34a among increased miRs in porcine AVICs after osteogenic treatment, which was consistent with results from patients with CAVS. MiR-34a increased calcium deposition in AVICs compared with miR-control. Notch1 expression was decreased, and Runx2 expression was increased in miR-34a transfected AVICs compared with that in miR-control. Conversely, inhibition of miR-34a significantly attenuated these calcification signals in AVICs compared with miR-control. RNA pull-down assay revealed that miR-34a directly targeted Notch1 expression by binding to Notch1 mRNA 3' untranslated region. In wire injury CAVS mice, locked nucleic acid miR-34a inhibitor suppressed aortic velocity, calcium deposition of aortic valves, and cardiac hypertrophy, which were involved in decreased Runx2 and increased Notch1 expressions.

CONCLUSION

miR-34a plays an important role in the development of CAVS via Notch1-Runx2 signalling pathway. Inhibition of miR-34a may be the therapeutic target for CAVS.

Activated platelets promote an osteogenic programme and the progression of calcific aortic valve stenosis

AIMS

Calcific aortic valve stenosis (CAVS) is characterized by a fibrocalcific process. Studies have shown an association between CAVS and the activation of platelets. It is believed that shear stress associated with CAVS promotes the activation of platelets. However, whether platelets actively participate to the mineralization of the aortic valve (AV) and the progression of CAVS is presently unknown. To identify the role of platelets into the pathobiology of CAVS.

METHODS AND RESULTS

Explanted control non-mineralized and mineralized AVs were examined by scanning electron microscope (SEM) for the presence of activated platelets. In-depth functional assays were carried out with isolated human valve interstitial cells (VICs) and platelets as well as in LDLR-/- apoB100/100 IGFII (IGFII) mice. Scanning electron microscope and immunogold markings for glycoprotein IIb/IIIa (GPIIb/IIIa) revealed the presence of platelet aggregates with fibrin in endothelium-denuded areas of CAVS. In isolated VICs, collagen-activated platelets induced an osteogenic programme. Platelet-derived adenosine diphosphate induced the release of autotaxin (ATX) by VICs. The binding of ATX to GPIIb/IIIa of platelets generated lysophosphatidic acid (LysoPA) with pro-osteogenic properties. In IGFII mice with CAVS, platelet aggregates were found at the surface of AVs. Administration of activated platelets to IGFII mice accelerated the development of CAVS by 2.1-fold, whereas a treatment with Ki16425, an antagonist of LysoPA receptors, prevented platelet-induced mineralization of the AV and the progression of CAVS.

CONCLUSIONS

These findings suggest a novel role for platelets in the progression of CAVS.

Lipid mass spectrometry imaging and proteomic analysis of severe aortic stenosis

Severe aortic stenosis (AS) is prevalent in adults ≥ 65 years, a significant cause of morbidity and mortality, with no medical therapy. Lipid and proteomic alterations of human AS tissue were determined using mass spectrometry imaging (MSI) and liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) to understand histopathology, potential biomarkers of disease, and progression from non-calcified to calcified phenotype. A reproducible MSI method was developed using healthy murine aortic valves (n = 3) and subsequently applied to human AS (n = 2). Relative lipid levels were spatially mapped and associated with different microdomains. Proteomics for non-calcified and calcified microdomains were performed to ascertain differences in expression. Increased pro-osteogenic and inflammatory lysophosphatidylcholine (LPC) 16:0 and 18:0 were co-localized with calcified microdomains. Proteomics analysis identified differential patterns in calcified microdomains with high LPC and low cholesterol as compared to non-calcified microdomains with low LPC and high cholesterol. Calcified microdomains had higher levels of: apolipoproteins (Apo) B-100 (p < 0.001) and Apo A-IV (p < 0.001), complement C3 and C4-B (p < 0.001), C5 (p = 0.007), C8 beta chain (p = 0.013) and C9 (p = 0.010), antithrombotic proteins alpha-2-macroglobulin (p < 0.0001) and antithrombin III (p = 0.002), and higher anti-calcific fetuin-A (p = 0.02), while the osteoblast differentiating factor transgelin (p < 0.0001), extracellular matrix proteins versican, prolargin, and lumican ( p < 0.001) and regulator protein complement factor H (p < 0.001) were higher in non-calcified microdomains. A combined lipidomic and proteomic approach provided insight into factors potentially contributing to progression from non-calcified to calcific disease in severe AS. Additional studies of these candidates and protein networks could yield new targets for slowing progression of AS.

MiRNA profiling revealed enhanced susceptibility to oxidative stress of endothelial cells from bicuspid aortic valve

AIMS

Calcific aortic valve stenosis (CAVS) is the most frequent manifestation of aortic valve disease and the third leading cause of cardiovascular disease in the Western countries associated with significant morbidity and mortality. An active biological progression involving inflammation and oxidation leading to valve endothelial damage is considered a hallmark of the early stages of valve degeneration. However, tricuspid (TAV) and bicuspid (BAV) aortic valve deterioration are considered to differ only by shear stress. We hypothesized that endothelial cells (EC) derived from BAV and TAV patients have different miRNA expression patterns and thus distinct pathways could lead to endothelial damage in BAV than TAV patients.

METHODS AND RESULTS

We isolated ECs from patients with bicuspid or tricuspid aortic valve, which underwent surgery due to CAVS. MiRNA expression profile by PCR revealed eight upregulated miRNAs between BAV and TAV ECs. Functional analysis identified that BAV ECs presented altered cellular response to oxidative stress and DNA damage stimulus via p53 and alteration in the intrinsic apoptotic signaling pathway. GPX3 and SRXN1 mRNA were express at lower levels in BAV compared to TAV ECs, leading to an increment of DNA double-strand breaks. BAV ECs had a sustained apoptosis activation when compared to TAV ECs. This difference was exacerbated by oxidative stress stimulus leading to a reduced survival rate but completely reverted by miR-328-3p inhibition.

CONCLUSION

The present data showed molecular differences in oxidative stress susceptibility, DNA damage magnitude, and apoptosis induction between ECs derived from BAV and TAV patients.

Life's simple 7 and calcific aortic valve stenosis incidence in apparently healthy men and women

BACKGROUND

Calcific aortic valve stenosis (CAVS) is the most prevalent heart valve disease in Western societies. The American Heart Association 2020 Strategic Impact Goals introduced the concept of ideal cardiovascular health, which includes seven cardiovascular health metrics, namely body mass index, a healthy diet, physical activity, smoking status, blood pressure, fasting plasma glucose and cholesterol levels. Several prospective studies have shown that compared to people who meet few of the criteria of ideal cardiovascular health, those with ideal cardiovascular health have an 80-90% lower risk of cardiovascular events. Whether or not ideal cardiovascular health is associated with CAVS risk is unknown. The purpose of this study was to assess the association between ideal cardiovascular health status and the risk of CAVS.

METHODS

In this analysis of the EPIC-Norfolk study, 21,856 participants were followed for 11.5 years and 430 of them developed CAVS. A cardiovascular health score was calculated based on the number of the seven health metrics.

RESULTS

In comparison to individuals in the bottom quartile of ideal cardiovascular health (CAVS event rate of 2,9%), those in the top quartile of the ideal cardiovascular health score had a relative risk of CAVS of 0,45 (95% CI 0,31-0,65, AVS event rate of 0,8%).

CONCLUSIONS

In apparently healthy individuals, modifiable clinical and lifestyle-related risk factors for CVD are strongly associated with the risk of CAVS, thereby suggesting that CAVS may be a preventable disease.

OxLDL-derived lysophosphatidic acid promotes the progression of aortic valve stenosis through a LPAR1-RhoA-NF-κB pathway

Aims

Oxidatively modified lipoproteins may promote the development/progression of calcific aortic valve stenosis (CAVS). Oxidative transformation of low-density lipoprotein (OxLDL) generates lysophosphatidic acid (LPA), a lipid mediator that accumulates in mineralized aortic valves. LPA activates at least six different G protein-coupled receptors, which may play a role in the pathophysiology of CAVS. We hypothesized that LPA derived from OxLDL may promote a NF-κB signature that drives osteogenesis in the aortic valve.

Methods and results

The role of OxLDL-LPA was examined in isolated valve interstitial cells (VICs) and the molecular pathway was validated in human explanted aortic valves and in a mouse model of CAVS. We found that OxLDL-LPA promoted the mineralization and osteogenic transition of VICs through LPAR1 and the activation of a RhoA-NF-κB pathway. Specifically, we identified that RhoA/ROCK activated IκB kinase alpha, which promoted the phosphorylation of p65 on serine 536 (p65 pS536). p65 pS536 was recruited to the BMP2 promoter and directed an osteogenic program not responsive to the control exerted by the inhibitor of kappa B. In LDLR-/-/ApoB100/100/IGFII transgenic mice (IGFII), which develop CAVS under a high-fat and high-sucrose diet the administration of Ki16425, a Lpar1 blocker, reduced by three-fold the progression rate of CAVS and also decreased the osteogenic activity as measured with a near-infrared fluorescent probe that recognizes hydroxyapatite of calcium.

Conclusions

OxLDL-LPA promotes an osteogenic program in the aortic valve through a LPAR1-RhoA/ROCK-p65 pS536 pathway. LPAR1 may represent a suitable target to prevent the progression of CAVS.

Functional SNP in the 3'UTR of PON1 is Associated with the Risk of Calcific Aortic Valve Stenosis via MiR-616

BACKGROUND/AIMS

Previous studies have examined the associations between the single nucleotide polymorphism in the Paraoxonase 1 (PON1) gene and development of calcific aortic valve stenosis (CAVS). The association between functional SNP in 3'UTR of PON1 and the risk of CAVS, however, is unclear. In this study, we investigated the role of SNP in the regulation of PON1 expression via miR-616, as well as the association of SNP with the risk of CAVS.

METHODS

Two hundred and sixteen patients with CAVS and 243 CAVS-free participants were recruited in this study.They all obtained transthoracic echocardiogram and the ejection fraction (EF) and aortic valve area were recorded and analyzed. The PON1 expression were measured by western blot, Quantitative Real-Time Polymerase Chain Reaction were used to examine the transcriptional activity of miR-616 and PON1. Differences between CVAS patients and controls in terms of genotype frequency distribution and the estimates of Hardy-Weinberg equilibrium were evaluated using chi-square tests. Logistic regression modeling was used to determine the association between the independent effect of rs3735590 SNP and the interaction between genotype, PON1 activity, and other covariates on lipids and CAVS risk. All statistical analyses were performed using SPSS, version 17.0.1 for Windows (SPSS Inc., Chicago, IL). A p value of < 0 .05 was considered significant for all analyses.

RESULTS

This study confirmed that PON1 is a validated target gene of miR-616 in liver cells. The relative quantification representing the expression of PON1 mRNA and the serum level of PON1 protein was decreased in the TT genotype. Moreover, the expression of PON1 had a negative regulatory relationship with the expression of miR-616(r=-0.3959, P<0.05) in human tissues. The patients with CT OR TT genotype at loci rs3735590 had a lower risk of CAVS than patients with the CC genotype.

CONCLUSIONS

Our results suggest that functional SNP in the 3'UTR of PON1 regulates the expression of PON1 via miR-616, and such SNP is associated with the risk of CAVS in human.

Simultaneous accurate quantification of HO-1, CD39, and CD73 in human calcified aortic valves using multiple enzyme digestion - filter aided sample pretreatment (MED-FASP) method and targeted proteomics

Several proteins such as membrane-associated ectonucleotidases: ecto-5'-nucleotidase (E5NT/CD73) and ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1/CD39), and intracellular heme oxygenase-1 (HO-1) may contribute to protection from inflammation-related diseases such as calcific aortic valve stenosis (CAS). Accurate quantification of these proteins could contribute to better understanding of the disease mechanisms and identification of biomarkers. This report presents development and validation of quantification method for E5NT/CD73, ENTPD1/CD39 and HO-1. The multiplexed targeted proteomic assay involved antibody-free, multiple-enzyme digestion, filter-assisted sample preparation (MED-FASP) strategy and a nanoflow liquid chromatography/mass spectrometry under multiple reaction monitoring mode (LC-MRM/MS). The method developed presented high sensitivity (LLOQ of 5 pg/mL for each of the analytes) and accuracy that ranged from 92.0% to 107.0%, and was successfully applied for the absolute quantification of HO-1, CD39 and CD73 proteins in homogenates of human calcified and non-calcified valves. The absolute CD39 and CD73 concentrations were lower in calcified aortic valves (as compared to non-stenotic ones) and were found to be: 1.16 ± 0.39 vs. 3.15 ± 0.37 pmol/mg protein and 1.94 ± 0.21 vs. 2.39 ± 0.39 pmol/mg protein, respectively, while the quantity of HO-1 was elevated in calcified valves (10.72 ± 1.18 vs. 4.28 ± 0.42 amol/mg protein). These results were consistent but more reproducible as compared to immunoassays. In conclusion, multiplexed quantification of HO-1, CD39 and CD73 proteins by LC-MRM/MS works well in challenging human tissues such as aortic valves. This analysis confirmed the relevance of these proteins in pathogenesis of CAS and could be extended to other biomedical investigations.

Movat Pentachrom stain reveals unexpected high osteogenesis rate in aortic valves

BACKGROUND AND AIM OF THE STUDY

Aortic valve (AV) stenosis is the most common valvular heart disease with an incidence of 3% for people ≥ 65years in the industrialized world with indication for a surgical or transcatheter valve replacement. Researchers suppose osteogenic processes as key mechanisms in calcific aortic valve stenosis. Recently, Torre et al. published impressive histological analyses and detected osseous and/or chondromatous metaplasia in 15.6% of 6685 native calcified aortic valves. Therefore one HE section per valve originated from the area with the greatest extent of calcification was analyzed. Aim of our experimental setup was to identify regions of neo-osteogenesis and to determine the rate of specimens with active mineralization in human aortic valve tissue by Movat Pentachrom staining of sections of lager tissue segments.

METHODS

Operational replaced aortic valves of 35 patients, 15 female and 20 male with an average age of 66.2 years were formalin fixed and decalcified using Osteosoft^®-solution. Tissue samples were cut and 2μm specimens were stained with Movat Pentachrom to visualize osteogenic regions. Instead of screening a large number of sections, tissue samples were cut up to five times with at least 100μm space each if no region of osseous and/or chondromatous metaplasia was visible.

RESULTS/CONCLUSIONS

Using this setup, a region of osseous metaplasia was detected in 25 (71.4%) of 35 samples analyzed. In some cases, these regions were small sized and only visible due to the bright color of Movat Pentachrom stain. This leads to the suggestion that a higher rate of calcified aortic valve samples would be classified as cusps with areas of neo-osteogenesis after staining with Movat Pentachrom stain and by the systematic analysis of larger parts of the tissue blocks.

Autoantibodies and immune complexes to oxidation-specific epitopes and progression of aortic stenosis: Results from the ASTRONOMER trial

BACKGROUND AND AIMS

Elevated levels of lipoprotein(a) [Lp(a)] and oxidized phospholipids on apolipoprotein B-100 (OxPL-apoB) predict the progression of pre-existing mild-to-moderate calcific aortic valve stenosis (CAVS). Whether indirect markers of oxidation-specific epitopes (OSE) are also predictive is not known. The association between IgG and IgM autoantibodies and malondialdehyde-modified low density lipoprotein (MDA-LDL) and IgG and IgM apolipoprotein B immune complexes (apoB-IC), and the hemodynamic progression rate of CAVS was determined in the ASTRONOMER (Aortic Stenosis Progression Observation: Measuring Effects of Rosuvastatin, NCT00800800) trial.

METHODS

Plasma levels of IgG and IgM MDA-LDL and apoB-IC were measured in 220 patients with mild-to-moderate CAVS from the ASTRONOMER trial. The endpoint of this study was the progression rate of CAVS, measured by the annualized increase in peak aortic jet velocity (V_peak) over a median follow-up of 3.5 [2.9-4.5] years.

RESULTS

There was no difference in the progression rate of CAVS across tertiles of IgG and IgM MDA-LDL and apoB-IC levels (all p > 0.05). After multivariable analysis, no marker reached significance level to predict faster CAVS progression or need for aortic valve replacement (all p > 0.05). There was no interaction between the OSE antibody titers and plasma levels of Lp(a) or OxPL-apoB, as well as age, with regards to the progression rate of CAVS.

CONCLUSIONS

Autoantibody titers to MDA-LDL and apoB-IC, which are an indirect measurement of OSE, unlike direct measurements of OxPL-apoB or their major lipoprotein carrier Lp(a), do not predict the progression of CAVS or need for AVR.

Osteopontin alters endothelial and valvular interstitial cell behaviour in calcific aortic valve stenosis through HMGB1 regulation

OBJECTIVES

Calcific aortic valve stenosis (CAVS) is an important clinical problem predominantly affecting elderly individuals. Studies suggest that the progression of CAVS is actively regulated with valve endothelial injury leading to inflammation, fibrosis and calcification. The aim of this study was to delineate the possible regulatory role of osteopontin (OPN) on high-mobility group box 1 (HMGB1) function and the associated inflammatory and fibrotic response in CAVS.

METHODS

Aortic valve leaflets were collected from CAVS patients undergoing aortic valve replacement (n = 40), and control aortic valve leaflets were obtained from heart transplant recipients (n = 15). Valves and plasma were analysed by quantitative real-time polymerase chain reaction (PCR), immunohistochemical staining and Western blot. Recombinant OPN or neutralizing OPN antibody was added to cultured endothelial and valvular interstitial cells (VICs), and cell proliferation scores and HMGB1 expression were assessed.

RESULTS

CAVS valves had a decreased total percentage of VICs but increased numbers of infiltrating macrophages relative to control valves. RT-PCR studies showed higher expression of OPN, the inflammatory cytokine tumour necrosis factor-alpha as well as markers of fibrosis, tissue inhibitor of matrix metalloproteinase 1 and matrix metalloproteinase 2 in CAVS valves. Elevated expression of OPN was also observed in plasma of CAVS patients compared with controls. HMGB1 was detected in the secretory granules of cultured valve endothelial and VICs derived from CAVS valves. The addition of exogenous OPN inhibited the proliferation of cultured endothelial and VICs from CAVS valves and was associated with the extracellular expression of HMGB1, whereas neutralizing OPN had the opposite effect.

CONCLUSIONS

We conclude that altered OPN expression in CAVS affects cellular HMGB1 function inducing cytoplasmic translocation and secretion of HMGB1 in endothelial cells and VICs, thus indicating a regulatory role for OPN in the progression of CAVS through alteration of HMGB1 function.

Role of serum high density lipoprotein levels and functions in calcific aortic valve stenosis progression

BACKGROUND

Clinical and epidemiological data well defines the role of atherosclerotic risk factors in pathogenesis of aortic stenosis. Especially dyslipidemia with elevated total and LDL cholesterol levels exerts certain histopathological changes on calcified valve tissue. Exact role of HDL in this process is not known.

OBJECTIVE

To evaluate the lipid profiles of patients with mild aortic valve stenosis with special focus on HDL; HDL subspecies, serum apoA1 levels, HDL related PON1 and PAF-AH enzyme activities and to correlate this with disease progression rates.

METHOD

42 patients (26 female; 16 male), with calcific aortic valve stenosis were enrolled in the study. Serum fasting lipid parameters, HDL subspecies (HDL2, HDL3), serum apoA1 levels and HDL related PON1 and PAF-AH enzyme activities were determined. All participants underwent detailed follow-up transthoracic echocardiography examination.

RESULTS

Among 42 study participants mean serum total cholesterol level was 195 ± 27.3 mg/dl, LDL-c level was 123 ± 19.1 mg/dl, HDL-c level was 44 ± 10.3 mg/dl and total cholesterol/HDL-c ratio was 4.64 ± 1.13. Basal peak aortic jet velocity (Vmax2) was 2.67 ± 0.39 m/sec, mean pressure gradient (Pmean2) was 15.6 ± 5.5 mmhg. Annual progression rate in peak aortic jet velocity (Vmax) was 0.23 ± 0.17 m/sec, in mean pressure gradient (Pmean) was 3 ± 2.1 mmhg. Annual progression rate in Pmean was most strongly correlated with serum HDL-c level and total/HDL-c ratio (r=-0.528 and 0.505; <0.001 and 0.001 respectively). Progression in Vmax values was positively correlated with serum LDL-c level and total/HDL-c ratio while negatively correlated with serum HDL-c levels (r=0.328, 0.499 and -0.464; P=0.034, 0.001 and 0.002 respectively). Among HDL subspecies HDL2 was the predominant type. HDL2 levels were found to be positively correlated with progression rates. There was no significant correlation between apolipoprotein A1 level and annual progression rate. Serum PON1 activity level was determined to be negatively correlated to doppler echocardiographic progression parameters while HDL related PAF-AH activity was independent of disease progression.

CONCLUSION

Present study demonstrated a positive correlation between disease progression and serum total cholesterol/HDL-c ratio. Serum HDL-c level was inversely correlated with hemodynamic progression. The majority of HDL was HDL2 subtype. Among HDL related enzymes PON1 enzyme activity exhibited an inverse correlation with disease progression.

Adenosine derived from ecto-nucleotidases in calcific aortic valve disease promotes mineralization through A2a adenosine receptor

AIMS

In this study, we sought to determine the role of ecto-nucleotidases and adenosine receptors in calcific aortic valve disease (CAVD). The expression of ecto-nucleotidases, which modify the levels of extracellular nucleotides/nucleosides, may control the mineralization of valve interstitial cells (VICs). We hypothesized that expression of ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1), which generates AMP, and 5'-nucleotidase (CD73), an enzyme using AMP as a substrate to produce adenosine, may co-regulate the mineralization of the aortic valve.

METHODS AND RESULTS

We have investigated the expression of NPP1 and 5'-nucleotidase in CAVD tissues and determined the role of these ecto-nucleotidases on the mineralization of isolated VICs. In CAVD tissues (stenotic and sclerotic), we documented that NPP1 and 5'-nucleotidase were overexpressed by VICs. In isolated VICs, we found that mineralization induced by adenosine triphosphate was decreased by silencing NPP1 and 5'-nucleotidase, suggesting a role for adenosine. Adenosine and specific A2a adenosine receptor (A2aR) agonist increased the mineralization of VICs. Silencing of A2aR in human VICs and the use of A2aR(-/-) mouse VICs confirmed that A2aR promotes the mineralization of cells. Also, A2aR-mediated mineralization was negated by the transfection of a mutant dominant-negative Gαs vector. Through several lines of evidence, we next documented that adenosine stimulated the mineralization of VICs through a cAMP/protein kinase A (PKA)/cAMP response element-binding protein (CREB) pathway, and found that CREB positively regulated the expression of NPP1 in a positive feedback loop by physically interacting with the promoter.

CONCLUSION

Expression of NPP1 and 5'-nucleotidase by VICs promotes the mineralization of the aortic valve through A2aR and a cAMP/PKA/CREB pathway.