Validation of plasma biomarkers in degenerative calcific aortic stenosis

Fetuin-A levels in association with calcific aortic valve disease: A meta-analysis

Background and aims

Calcific aortic valve disease (CAVD) is a common valvular disease, prevalent particularly within the older age groups. The potential use of biomarkers in diagnosing and assessing the severity of CAVD, in supplementation with imaging techniques, has recently gained momentum within the field of cardiovascular medicine. Therefore, a meta-analysis was performed that assessed the association between the fetuin-A levels, and the presence of CAVD.

Methods

PubMed and Cochrane were searched from inception to April 2023. Risk of bias was assessed using the Newcastle-Ottawa scale for cohort studies.

Results

This analysis includes a total of 3,280 patients with CAVD, and 7,505 patients as control, resulting in the pooling of 10,785 patients in this meta-analysis. It was observed that the circulating levels of fetuin-A were significantly lowered in patients with CAVD (SMD: -0.20; 95% CI: -0.39, -0.02; P = 0.03). Moreover, the analysis revealed that fetuin-A levels had no significant association with CAVD in patients suffering from kidney disease (SMD: 0.20; 95% CI: -0.46, 0.85; P = 0.56).

Conclusion

While initial results demonstrate the potential effectiveness, further research is essential in order to arrive at a robust conclusion regarding the use of fetuin-A as a diagnostic biomarker for calcific aortic valve disease.

Clinical and Molecular Implications of Osteopontin in Heart Failure

The matricellular protein osteopontin modulates cell-matrix interactions during tissue injury and healing. A complex multidomain structure of osteopontin enables it not only to bind diverse cell receptors but also to interact with various partners, including other extracellular matrix proteins, cytokines, and growth factors. Numerous studies have implicated osteopontin in the development and progression of myocardial remodeling in diverse cardiac diseases. Osteopontin influences myocardial remodeling by regulating extracellular matrix production, the activity of matrix metalloproteinases and various growth factors, inflammatory cell recruitment, myofibroblast differentiation, cardiomyocyte apoptosis, and myocardial vascularization. The exploitation of osteopontin loss- and gain-of-function approaches in rodent models provided an opportunity for assessment of the cell- and disease-specific contribution of osteopontin to myocardial remodeling. In this review, we summarize the recent knowledge on osteopontin regulation and its impact on various cardiac diseases, as well as delineate complex disease- and cell-specific roles of osteopontin in cardiac pathologies. We also discuss the current progress of therapeutics targeting osteopontin that may facilitate the development of a novel strategy for heart failure treatment.

Causal effects of homocysteine levels on the changes of bone mineral density and risk for bone fracture: A two-sample mendelian randomization study

BACKGROUND & AIMS

Observational studies have demonstrated the relations of homocysteine (HCY) with bone mineral density (BMD) and bone fracture risk, but yielding contradictory results. The present study was conducted to evaluate whether the genetically predicted plasma HCY levels were causally associated with the change of BMD and the risk of bone fracture.

METHODS

Genetic summary statistics were extracted from genome-wide association study (GWAS) meta-analysis of plasma HCY levels (n = 44,147), GWAS meta-analyses of measured forearm (FA), femoral neck (FN) and lumbar spine (LS) BMD (n = up to 32,735), UK Biobank estimated heel BMD (eBMD) (n = 426,824) and fracture (n = 426,795) GWAS data. Two Sample Mendelian Randomization (TSMR) analysis was performed to assess the causal effects of genetically determined plasma HCY on the BMD and bone fractures.

RESULTS

The MR analysis indicated that, genetically decreased plasma HCY was associated with the increased FA-BMD based on the inverse variance weighting (IVW) method (standard deviation [SD] = 0.348, 95% CI: 0.146 to 0.550, P = 7 × 10^-4). However, there were no significant associations of genetically decreased plasma HCY with FN-BMD, LS-BMD, eBMD and the risk for bone fracture (SD = -0.041, 95% CI: -0.189 to 0.106, P = 0.582; SD = -0.053, 95% CI: -0.238 to 0.131, P = 0.572; SD = -0.030, 95% CI: -0.090 to 0.030, P = 0.328, odds ratio [OR]: 1.03, 95% CI: 0.94 to 1.13, P = 0.562, respectively). Moreover, the results also found that genetically determined HCY increase was not correlated with the changes of BMD and the risk for bone fracture.

CONCLUSION

Our study revealed that genetically decreased plasma HCY was associated with increase of FA-BMD.

Serum Biomarkers of Cardiovascular Remodelling Reflect Extra-Valvular Cardiac Damage in Patients with Severe Aortic Stenosis

In patients with aortic stenosis (AS), a novel staging classification of extra-valvular left and right heart damage with prognostic relevance was introduced in 2017. The aim of the study was to evaluate the biomarkers of cardiovascular tissue remodelling in relation to this novel staging classification. Patients were categorized according to the novel staging classification into stages 0 to 4. The levels of matrix metalloproteinase 9 (MMP-9), tissue inhibitor of metalloproteinases 1 (TIMP-1), B and C domain containing tenascin-C (B⁺ Tn-C, C⁺ Tn-C), the ED-A and ED-B domain containing fibronectin (ED-A⁺ Fn, ED-B⁺ Fn), endothelin 1 (ET-1) and neutrophil gelatinase-associated lipocalin (NGAL) were determined in serum by ELISA. There were significantly decreased serum levels of MMP-9 and increased levels of B⁺ Tn-C and C⁺ Tn-C when comparing stages 0 and 1 with stage 2, with no further dynamics in stages 3 and 4. In contrast, for TIMP-1, C⁺ Tn-C, ED-A⁺ Fn, ET-1 and NGAL, significantly increased serum levels could be detected in stages 3 and 4 compared to both stages 0 and 1 and stage 2. ED-A⁺ Fn and ET-1 could be identified as independent predictors of the presence of stage 3 and/or 4. To the best of our knowledge, this is the first study identifying novel serum biomarkers differentially reflecting the patterns of left and right heart extra-valvular damage in patients suffering from AS. Our findings might indicate a more precise initial diagnosis and risk stratification.

Blood biomarkers in patients with bicuspid aortic valve disease

BACKGROUND

Patients with a bicuspid aortic valve (BAV) are at risk of developing valve deterioration and aortic dilatation. We aimed to investigate whether blood biomarkers are associated with disease stage in patients with BAV.

METHODS

Serum levels of high sensitivity C-reactive protein (hsCRP), high sensitivity troponin T (hsTnT), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and total transforming growth factor-beta 1 (TGF-ß1) were measured in adult BAV patients with valve dysfunction or aortic pathology. Age-matched general population controls were included for TGFß-1 measurements. Correlation analyses and multivariable linear regression were used to determine the association between (2log-transformed) biomarker levels and aortic valve regurgitation, aortic valve stenosis, aortic dilatation, or left ventricular function.

RESULTS

hsCRP and hsTnT were measured in the total group of 183 patients (median age 34 years, 25th-75th percentile 23-46), NT-proBNP in 162 patients, and TGF-ß1 beta in 108 patients. Elevated levels of NT-proBNP were found in 20% of the BAV patients, elevated hsTnT in 6%, and elevated hsCRP in 7%. Higher hsTnT levels were independently associated with aortic regurgitation [odds ratio per doubling (OR_2log) 1.34, 95% CI 1.01;1.76] and higher NT-proBNP levels with aortic valve maximal velocity (ß_2log 0.17, 95%CI 0.07;0.28) and aortic regurgitation (OR_2log 1.41, 95%CI 1.11;1.79). Both BAV patients with (9.9 ± 2.7 ng/mL) and without aortic dilatation (10.4 ± 2.9 ng/mL) showed lower TGF-ß1 levels compared to general population controls (n = 85, 11.8 ± 3.2 ng/mL).

CONCLUSIONS

Higher NT-proBNP and hsTNT levels were associated with aortic valve disease in BAV patients. TGF-ß1 levels were lower in BAV patients than in the general population, and not related to aortic dilatation. Longitudinal data are needed to further investigate the prognostic value of biomarkers in these patients.

Circulating and tissue matricellular RNA and protein expression in calcific aortic valve disease

Aortic valve sclerosis is a highly prevalent, poorly characterized asymptomatic manifestation of calcific aortic valve disease and may represent a therapeutic target for disease mitigation. Human aortic valve cusps and blood were obtained from 333 patients undergoing cardiac surgery (n = 236 for severe aortic stenosis, n = 35 for asymptomatic aortic valve sclerosis, n = 62 for no valvular disease), and a multiplex assay was used to evaluate protein expression across the spectrum of calcific aortic valve disease. A subset of six valvular tissue samples (n = 3 for asymptomatic aortic valve sclerosis, n = 3 for severe aortic stenosis) was used to create RNA sequencing profiles, which were subsequently organized into clinically relevant gene modules. RNA sequencing identified 182 protein-encoding, differentially expressed genes in aortic valve sclerosis vs. aortic stenosis; 85% and 89% of expressed genes overlapped in aortic stenosis and aortic valve sclerosis, respectively, which decreased to 55% and 84% when we targeted highly expressed genes. Bioinformatic analyses identified six differentially expressed genes encoding key extracellular matrix regulators: TBHS2, SPARC, COL1A2, COL1A1, SPP1, and CTGF. Differential expression of key circulating biomarkers of extracellular matrix reorganization was observed in control vs. aortic valve sclerosis (osteopontin), control vs. aortic stenosis (osteoprotegerin), and aortic valve sclerosis vs. aortic stenosis groups (MMP-2), which corresponded to valvular mRNA expression. We demonstrate distinct mRNA and protein expression underlying aortic valve sclerosis and aortic stenosis. We anticipate that extracellular matrix regulators can serve as circulating biomarkers of early calcific aortic valve disease and as novel targets for early disease mitigation, pending prospective clinical investigations.

Factors Influencing Serum Homocysteine Levels in Postmenopausal Osteoporotic Females - Comparison to Urinary Collagen Crosslinks

Purpose: The correlation between serum levels of homocysteine and bone mineral density remains controversial. The aim of this study was to identify the potential factors associated with the levels of serum total homocysteine (S-Hcy) and urinary N-terminal telopeptide of type I collagen (U-NTX) in female osteoporotic patients. Materials and Methods: This cross-sectional study included 163 female osteoporotic patients, aged between 48 and 91 years, who had never been treated with anti-osteoporosis therapy. Background data including spine and hip bone mineral density, ongoing therapy for the metabolic disease, aortic calcification score as evaluated by lateral lumbar X-ray film, and recent fragility fracture history were obtained. S-Hcy, U-NTX levels, and creatinine clearance were measured. Results: Multiple linear regression analysis revealed a significant correlation between S-Hcy levels and aortic calcification score (p = 0.022), creatinine clearance (p = 0.004), and recent fracture history (within 1 year after fracture) (p = 0.028); conversely, U-NTX levels correlated significantly with total hip bone mineral density (p < 0.0001) and recent fracture history (p = 0.0007). Conclusions: S-Hcy levels had no correlation with bone mineral density, but were associated with the degree of aortic calcification, renal function, and fracture events. These confounding factors should be taken into consideration when the relationship between S-Hcy and bone mineral density is discussed.

Coffee consumption and risk of aortic valve stenosis: A prospective study

BACKGROUND AND AIMS

Coffee contains many biologically active compounds with potential adverse or beneficial effects on the cardiovascular system. Whether coffee consumption is associated with the risk of aortic valve stenosis (AVS) is unknown. The purpose of this study was therefore to examine the association between coffee consumption and AVS incidence.

METHODS AND RESULTS

This prospective study included 71 178 men and women who provided information on their coffee consumption through a questionnaire at baseline. Incident cases of AVS were identified through linkage with the Swedish National Patient and Cause of Death Registers. During a mean follow-up of 15.2 years, 1295 participants (777 men and 518 women) were diagnosed with AVS. Coffee consumption was positively associated with risk of AVS in a dose-response manner after adjustment for age, sex, smoking, and other risk factors (P-trend = 0.005). The multivariable hazard ratios were was 1.11 (95% confidence interval 1.04-1.19) per 2 cups/day increase of coffee consumption and 1.65 (95% confidence interval 1.10-2.48) when comparing the highest (≥6 cups/day) with the lowest (<0.5 cup/day) category of coffee consumption. The association was not modified by other risk factors.

CONCLUSIONS

This study provides novel evidence that high coffee consumption is associated with an increased risk of AVS.

Association between homocysteine levels and calcific aortic valve disease: a systematic review and meta-analysis

Previous studies have reported inconsistent results regarding the association between homocysteine (Hcy) levels and calcific aortic valve disease (CAVD). We investigate the association between Hcy levels in patients with CAVD and controls by conducting a systematic review and meta-analysis. We conducted a systematic search of studies published prior to the end of March 2017 in the PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials and the Chinese Biomedical Literature databases. Eligible studies evaluating plasma Hcy levels in CAVD patients and controls were identified by two independent investigators. Standardized mean difference (SMD) and the corresponding 95% confidence intervals (95% CIs) were estimated using the random-effects model. Ten studies involving 6349 participants were included. Pooled analysis demonstrated that Hcy levels were significantly elevated in patients with CAVD compared with controls (pooled SMD: 0.57, 95% CI: 0.36–0.79). This elevation was more obvious in American and Asian populations than in Turkish populations. Furthermore, Hcy levels were significantly elevated in patients with mild-to-moderate CAVD and severe CAVD. Our results demonstrate that CAVD is associated with elevated Hcy levels.

Aortic stenosis: insights on pathogenesis and clinical implications

Aortic stenosis (AS) is a common valvular heart disease in the Western populations, with an estimated overall prevalence of 3% in adults over 75 years. To understand its patho-biological processes represents a priority. In elderly patients, AS usually involves trileaflet valves and is referred to as degenerative calcific processes. Scientific evidence suggests the involvement of an active "atherosclerosis-like" pathogenesis in the initiation phase of degenerative AS. To the contrary, the progression could be driven by different forces (such as mechanical stress, genetic factors and interaction between inflammation and calcification). The improved understanding presents potentially new therapeutic targets for preventing and inhibiting the development and progression of the disease. Furthermore, in clinical practice the management of AS patients implies the evaluation of generalized atherosclerotic manifestations (i.e., in the coronary and carotid arteries) even for prognostic reasons. In counselling elderly patients, the risk stratification should address individual frailty beyond the generic risk scores. In these regard, the co-morbidities, and in particular those linked to the global atherosclerotic burden, should be carefully investigated in order to define the risk/benefit ratio for invasive treatment strategies. We present a detailed overview of insights in pathogenesis of AS with possible practical implications.

Microparticles in patients undergoing transcatheter aortic valve implantation (TAVI)

Degenerative aortic stenosis (AS) is the most frequent form of acquired valvular heart disease. AS is known to entail endothelial dysfunction caused by increased mechanical shear stress leading to elevated circulatory levels of microparticles. Endothelial and platelet microparticles (EMP and PMP) are small vesicles that originate from activated cells and thrombocytes. We sought to evaluate whether transcatheter aortic valve implantation (TAVI) procedure would elicit effects on circulating EMP and PMP. 92 patients undergoing TAVI procedure for severe AS were included in this study. Samples were obtained at each visit before TAVI, 1 week post-procedure and at 1, 3 and after 6 months after TAVI and were evaluated using flow cytometry. A 12 month clinical follow-up was also performed. CD62E+ EMP concentration before TAVI was 21.11 % (±6.6 % SD) and declined to 20.99 % (±6.8 % SD) after 1 week, to 16.63 % (±5.4 % SD, p < 0.0001) after 1 month, to 17.08 % (±4.6 % SD, p < 0.0001) after 3 months and to 15.94 % (±5.4 % SD, p < 0.0001) after 6 months. CD31+/CD42b-, CD31+/Annexin+/- EMP remained unchanged. CD31+/CD41b+ PMP evidenced a slight, but statistically significant increase after TAVI and remained elevated during the entire follow-up. Apart from a procedure-related improvement in echocardiographic parameters, TAVI procedure led also to a decline in CD62E+ EMP. The reduction in pressure gradients with less hemodynamic shear stress seems also to have beneficially affected endothelial homeostasis.

Association of inflammatory, lipid and mineral markers with cardiac calcification in older adults

OBJECTIVE

Calcification of the aortic valve and adjacent structures involves inflammatory, lipid and mineral metabolism pathways. We hypothesised that circulating biomarkers reflecting these pathways are associated with cardiac calcification in older adults.

METHODS

We investigated the associations of various biomarkers with valvular and annular calcification in the Cardiovascular Health Study. Of the 5888 participants, up to 3585 were eligible after exclusions for missing biomarker, covariate or echocardiographic data. We evaluated analytes reflecting lipid (lipoprotein (Lp) (a), Lp-associated phospholipase A₂ (LpPLA₂) mass and activity), inflammatory (interleukin-6, soluble (s) CD14) and mineral metabolism (fetuin-A, fibroblast growth factor (FGF)-23) pathways that were measured within 5 years of echocardiography. The relationships of plasma biomarkers with aortic valve calcification (AVC), aortic annular calcification (AAC) and mitral annular calcification (MAC) were assessed with relative risk (RR) regression.

RESULTS

Calcification was prevalent: AVC 59%, AAC 45% and MAC 41%. After adjustment, Lp(a), LpPLA₂ mass and activity and sCD14 were positively associated with AVC. RRs for AVC per SD (95% CI) were as follows: Lp(a), 1.051 (1.022 to 1.081); LpPLA₂ mass, 1.036 (1.006 to 1.066) and LpPLA₂ activity, 1.037 (1.004 to 1.071); sCD14, 1.039 (1.005 to 1.073). FGF-23 was positively associated with MAC, 1.040 (1.004 to 1.078) and fetuin-A was negatively associated, 0.949 (0.911 to 0.989). No biomarkers were significantly associated with AAC.

CONCLUSION

This study shows novel associations of circulating FGF-23 and fetuin-A with MAC, and LpPLA₂ and sCD14 with AVC, confirming that previously reported for Lp(a). Further investigation of Lp and inflammatory pathways may provide added insight into the aetiology of AVC, while study of phosphate regulation may illuminate the pathogenesis of MAC.

Serum and tissue biomarkers in aortic stenosis

Background: Calcific aortic valve stenosis (CAVS) is seen in a large proportion of individuals over 60 years. It is an active process, influenced by lipid accumulation, mechanical stress, inflammation, and abnormal extracellular matrix turnover. Various biomarkers (BMs) are studied, as regards mechanisms, diagnosis and prognosis. Methods: In the calcified valves calcium deposition, elastin fragmentation and disorganization of cellular matrix were assessed, together with expression of OPN, OPG, osteocalcin (OCN) and RL2.

We prospectively studied the following serum BMs in 60 patients with CAVS and compared them to 20 healthy controls, free from any cardiac disease: Matrix metalloproteinases (MMP) 2 and 9 and tissue inhibitor of metalloproteinase 1 (TIMP1), which regulate collagen turnover, inflammatory factors, i.e. tumor necrosis factor a (TNFa), interleukin 2 (IL2), transforming growth factor β1 (TGF-β1) which regulates fibrosis, fetuin-A (fet-A), osteopontin (OPN), osteoprotegerin (OPG), sclerostin (SOST), and relaxin-2 (RL2) which positively or negatively regulate calcification. Monocyte chemoattractant protein 1 (MCP-1) which regulates migration and infiltration of monocytes/macrophages was also studied as well as malondialdehyde (MDA) an oxidative marker. Results: Extent of tissue valve calcification (Alizarin Red stain) was negatively correlated with tissue elastin, and RL2, and positively correlated with tissue OCN and serum TIMP1 and MCP-1 and negatively with MMP9.

Tissue OCN was positively correlated with OPN and negatively with the elastin. Tissue OPN was negatively correlated with elastin and OPG. Tissue OPN OPG and RL2 were not correlated with serum levels In the serum we found in patients statistically lower TIMP1, fet-A and RL2 levels, while all other BMs were higher compared to the healthy group. Positive correlations between SOST and IL2, OPG and MDA but negative with TNFa and OPN were found; also MMP9 was negatively correlated with TNFa and MCP-1 was negatively correlated with TIMP1. Conclusion: We found that many BMs expressing calcification, collagen breakdown, or formation, and inflammation are increased in the valve tissue and in the serum of patients with CAVS as compared with healthy group. Our findings may give new insights towards diagnosis but also therapy. Thus antisclerostin, and antiflammatory agents could be tried for preventing aortic calcification progression.

Osteopontin-CD44v6 interaction mediates calcium deposition via phospho-Akt in valve interstitial cells from patients with noncalcified aortic valve sclerosis

OBJECTIVE

The activation of valve interstitial cells (VICs) toward an osteogenic phenotype characterizes aortic valve sclerosis, the early asymptomatic phase of calcific aortic valve disease. Osteopontin is a phosphorylated acidic glycoprotein that accumulates within the aortic leaflets and labels VIC activation even in noncalcified asymptomatic patients. Despite this, osteopontin protects VICs against in vitro calcification. Here, we hypothesize that the specific interaction of osteopontin with CD44v6, and the related intracellular pathway, prevents calcium deposition in human-derived VICs from patients with aortic valve sclerosis.

APPROACH AND RESULTS

On informed consent, 23 patients and 4 controls were enrolled through the cardiac surgery and heart transplant programs. Human aortic valves and VICs were tested for osteogenic transdifferentiation, ex vivo and in vitro. Osteopontin-CD44 interaction was analyzed using proximity ligation assay and the signaling pathways investigated. A murine model based on angiotensin II infusion was used to mimic early pathological remodeling of the aortic valves. We report osteopontin-CD44 functional interaction as a hallmark of early stages of calcific aortic valve disease. We demonstrated that osteopontin-CD44 interaction mediates calcium deposition via phospho-Akt in VICs from patients with noncalcified aortic valve sclerosis. Finally, microdissection analysis of murine valves shows increased cusp thickness in angiotensin II-treated mice versus saline infused along with colocalization of osteopontin and CD44 as seen in human lesions.

CONCLUSIONS

Here, we unveil a specific protein-protein association and intracellular signaling mechanisms of osteopontin. Understanding the molecular mechanisms of early VIC activation and calcium deposition in asymptomatic stage of calcific aortic valve disease could open new prospective for diagnosis and therapeutic intervention.

Aortic valve calcification in chronic kidney disease

Several clinical studies reported an increased prevalence and accelerated progression of aortic valve calcification among patients with end-stage renal disease when compared with subjects with normal kidney function. Recently, mechanisms of calcific valve degeneration have been further elucidated and many of the pathways involved could be amplified in patients with decreased renal function. In particular, calcium-phosphate balance, MGP metabolism, OPG/RANK/RANKL triad, fetuin-A mineral complexes and FGF-23/Klotho axis have been shown to be impaired among patients with advanced chronic kidney disease and could play a role during vascular/valve calcification. The scope of the present review is to summarize the clinical data and the pathophysiological mechanisms potentially involved in the link between renal function decline and the progression of aortic valve disease.

Oxidative stress and nitric oxide pathway in adult patients who are candidates for cardiac surgery: patterns and differences

OBJECTIVES

We investigated whether oxidative stress and the arginine/nitric oxide pathway differ in control subjects and in adult patients who are candidates for the three most common cardiac surgical operations: coronary bypass surgery, aortic valve replacement for calcific non-rheumatic aortic stenosis or mitral valve repair for degenerative mitral insufficiency.

METHODS

In this prospective observational study, we studied 165 consecutive patients undergoing surgery from January to June 2011 (coronary bypass surgery, n = 63; aortic valve replacement for calcific non-rheumatic aortic stenosis, n = 51; mitral valve repair for degenerative mitral insufficiency, n = 51). Thirty-three healthy subjects with cardiovascular risk factors similar to surgery patients were also studied (Controls). Oxidative stress (the ratio of reduced and oxidized glutathione and urinary isoprostane), antioxidants (alpha- and gamma tocopherol) and factors involved in nitric oxide synthesis (arginine, symmetric and asymmetric dimethylarginine) were measured before surgery. Analysis of variance general linear models and principal component analysis were used for statistical analysis.

RESULTS

Surgical patients had increased levels of oxidative stress and decreased levels of antioxidants. Increased levels of nitric oxide inhibitor asymmetric dimethylarginine were detected in surgical candidates, suggesting arginine/nitric oxide pathway impairment. Concerning the differences among surgical procedures, higher oxidative stress and a major imbalance of the ratio between substrate and inhibitors of nitric oxide synthesis were evidenced in patients who were candidates for mitral valve repair with respect to coronary bypass surgery patients and patients with calcific non-rheumatic aortic stenosis.

CONCLUSIONS

Patients undergoing cardiac surgery have increased oxidative stress and a trend towards an impaired arginine/nitric oxide pathway with respect to Controls. Patients affected by mitral valve regurgitation show more pronounced perturbations in these pathways. The clinical implications of these findings need to be investigated.

Comparison of transesophageal echocardiographic analysis and circulating biomarker expression profile in calcific aortic valve disease

BACKGROUND AND AIM OF THE STUDY

Aortic valve sclerosis (AVSc), the early asymptomatic stage of calcific aortic valve disease (CAVD), is characterized by a progressive thickening of the aortic cusps without obstruction of the left ventricular outflow. In spite of its high prevalence, there are no molecular markers to characterize the early stages of CAVD before it progresses to a severe, symptomatic stage of aortic valve stenosis (AVS). The study aim was to identify any correlation between circulating biomarkers and transesophageal echocardiography (TEE) evaluation.

METHODS

A total of 330 patients with various degrees of CAVD was enrolled into the study. Blood was collected from each patient prior to surgery, and analyzed using ELISA kits following the manufacturers' instructions.

RESULTS

Significantly higher plasma osteopontin (OPN) levels were observed in AVSc patients (72.7 +/- 1.8 ng/ml; p < 0.001) and AVS patients (64.3 +/- 5.1 ng/ml; p < 0.001) when compared to controls (30.3 +/- 1.8 ng/ml). Parathyroid hormone (PTH) levels in AVSc and AVS patients (164.1 +/- 16.5 and 134.3 +/- 14.6 pg/ml; p < 0.001 and p = 0.04, respectively) were also significantly higher than in controls (61.8 +/- 4.92 pg/ml). Upon further analysis, plasma levels of OPN (p < 0.001) and PTH (p < 0.001) were found to be significantly higher in asymptomatic AVSc patients, even before calcium deposition was detected on TEE evaluation. Fetuin-A levels were lower at all stages of CAVD when compared to controls (p < 0.001 and p < or = 0.05, respectively), but were comparable among the patient groups. NT-proBNP levels were significantly higher in AVS patients than in controls (p < or = 0.01).

CONCLUSION

Serum levels of OPN, PTH, and fetuin-A showed a significant association with different stages of CAVD, with variations in their levels occurring before calcium nodules are visualized during TEE evaluation. The study results may help not only to provide a better understanding of the progression of CAVD but also to develop new tools that can be used to stage these patients.

Valvular osteoclasts in calcification and aortic valve stenosis severity

BACKGROUND

Bone remodeling in calcified aortic valves is thought to originate from microfractures at multiple sites of the valve, at which osteoclasts and osteoblasts are recruited. The aim of the present study was to assess circulating mediators of bone homeostasis, correlate them to the severity of stenosis and explore the spatio-temporal distribution of bone turnover in different parts of calcified aortic valve tissue.

METHODS AND RESULTS

Plasma and explanted aortic valves were obtained from 46 patients undergoing aortic valve replacement surgery. Plasma levels of tartrate-resistant acid phosphatase (TRAP), receptor activator of nuclear-κB (RANK) ligand and Runt-related transcription factor 2 (Runx2/Cbfa1) exhibited a significant correlation to the severity of aortic stenosis. mRNA levels in normal, thickened and calcified parts of aortic valves assessed by quantitative real-time PCR were significantly elevated in calcified parts of valves for TRAP (5.08 ± 1.6-fold, P<0.001) RANK ligand (8.6 ± 4.2-fold, P<0.001) and RANK (1.98 ± 0.78-fold, P=0.015). In an age, gender and aortic valve anatomy-adjusted multivariable regression analysis the local transcript levels of TRAP correlated significantly with echocardiographic parameters quantifying stenosis severity in early stages, whereas the expression level of Runx2/Cbfa1 was a predictor of the stenosis severity in advanced stages.

CONCLUSIONS

These findings suggest a critical role of bone turnover as a determinant of aortic stenosis severity.

Antioxidant enzymes reduce DNA damage and early activation of valvular interstitial cells in aortic valve sclerosis

OBJECTIVE

Accumulation of reactive oxygen species (ROS) and remodeling of the microstructure of the cusp characterize aortic valve sclerosis, the early phase of calcific aortic valve disease. These events are associated with activation of valvular interstitial cells (VICs) toward an osteogenic-like phenotype. Because ROS cause DNA damage and transcriptional activation we investigated the relationship between ROS, DNA damage response, and transdifferentiation of VICs.

METHODS AND RESULTS

Human aortic valve cusps and patient-matched VICs were collected from 39 patients both with and without calcific aortic valve disease. VICs were exposed to hydrogen peroxide (0.1-1 mmol/L) after cell transduction with extracellular superoxide dismutase/catalase adenoviruses and characterized for DNA-damage response, osteogenic transdifferentiation, and calcification. ROS induce relocalization of phosphorylated γH2AX, MRE11, and XRCC1 proteins with expression of osteogenic signaling molecule RUNX2 via AKT. We report a sustained activation of γH2AX in aortic valve sclerosis-derived VICs suggesting their impaired ability to repair DNA damage. Adenovirus superoxide dismutase/catalase transduction decreases ROS-induced DNA damage and VIC transdifferentiation in aortic valve sclerosis-derived cells. Finally, adenoviral transduction with catalase reverts ROS-mediated calcification and cellular transdifferentiation.

CONCLUSIONS

We conclude that the ROS-induced DNA damage response is dysfunctional in early asymptomatic stages of calcific aortic valve disease. We unveiled an association among ROS, DNA-damage response, and cellular transdifferentiation, reversible by antioxidant enzymes delivery.

Matricellular proteins in cardiac adaptation and disease

The term matricellular proteins describes a family of structurally unrelated extracellular macromolecules that, unlike structural matrix proteins, do not play a primary role in tissue architecture, but are induced following injury and modulate cell-cell and cell-matrix interactions. When released to the matrix, matricellular proteins associate with growth factors, cytokines, and other bioactive effectors and bind to cell surface receptors transducing signaling cascades. Matricellular proteins are upregulated in the injured and remodeling heart and play an important role in regulation of inflammatory, reparative, fibrotic and angiogenic pathways. Thrombospondin (TSP)-1, -2, and -4 as well as tenascin-C and -X secreted protein acidic and rich in cysteine (SPARC), osteopontin, periostin, and members of the CCN family (including CCN1 and CCN2/connective tissue growth factor) are involved in a variety of cardiac pathophysiological conditions, including myocardial infarction, cardiac hypertrophy and fibrosis, aging-associated myocardial remodeling, myocarditis, diabetic cardiomyopathy, and valvular disease. This review discusses the properties and characteristics of the matricellular proteins and presents our current knowledge on their role in cardiac adaptation and disease. Understanding the role of matricellular proteins in myocardial pathophysiology and identification of the functional domains responsible for their actions may lead to design of peptides with therapeutic potential for patients with heart disease.

Fetuin-A and the cardiovascular system

Fetuin was first isolated from bovine serum in 1944. It is now most commonly known as either fetuin-A or alpha-2-HS-glycoprotein (AHSG), the protein product of Ahsg gene. A prominent feature of this protein is the functional diversity exerted in human physiology and pathophysiology. Fetuin-A plays a role in bone metabolism, metabolic disorders such as insulin resistance and diabetes mellitus (DM), and central nervous system (CNS) disorders such as ischemic stroke (IS) and neurodegenerative diseases. In addition, emerging evidence suggests involvement of fetuin-A in the cardiovascular system. However, there are many discordant findings on the associations between fetuin-A and vascular diseases. In other words, it is unknown whether fetuin-A is an exacerbating or a protective factor in the cardiovascular system. One reason for the seemingly inconsistent behavior is the dual functionality of fetuin-A in vascular diseases where it can act as an atherogenic factor or as a vascular calcification inhibitor. In addition, the existence of confounding factors such as DM and renal dysfunction can veil the primary association between fetuin-A and clinical parameters. Considering these issues, we discuss the role of fetuin-A for atherosclerosis and vascular calcification in this review.

Myocardial remodeling with aortic stenosis and after aortic valve replacement: mechanisms and future prognostic implications

Aortic valve stenosis is a common cause of left ventricular pressure overload, a pathologic process that elicits myocyte hypertrophy and alterations in extracellular matrix composition, both of which contribute to increases in left ventricular stiffness. However, clinical and animal studies suggest that increased myocardial extracellular matrix fibrillar collagen content occurs later in the time course of left ventricular pressure overload at a time coincident with severe abnormalities in diastolic function followed by the development of symptomatic heart failure. Aortic valve replacement remains the most effective treatment for elimination of chronic pressure overload secondary to aortic stenosis but has traditionally been recommended only after the onset of clinical symptoms. Long-term follow-up of patients with symptomatic aortic stenosis after aortic valve replacement suggests that valve replacement may not result in complete reversal of the maladaptive changes that occur within the myocardial extracellular matrix secondary to the pressure overload state. To the contrary, residual left ventricular extracellular matrix abnormalities such as these are likely responsible for persistent abnormalities in diastolic function and increased morbidity and mortality after aortic valve replacement. Defining the mechanisms and pathways responsible for regulating the myocardial extracellular matrix during the natural history of aortic stenosis may provide a means by which to detect crucial structural milestones and thereby permit more precise identification of the development of maladaptive left ventricular remodeling.