Plasma homocysteine and calcific aortic valve disease

Hyperhomocysteinemia in Adult Patients: A Treatable Metabolic Condition

Hyperhomocysteinemia (HHcy) is recognized as an independent risk factor for various significant medical conditions, yet controversy persists around its assessment and management. The diagnosis of disorders afffecting homocysteine (Hcy) metabolism faces delays due to insufficient awareness of its clinical presentation and unique biochemical characteristics. In cases of arterial or venous thrombotic vascular events, particularly with other comorbidities, it is crucial to consider moderate to severe HHcy. A nutritional approach to HHcy management involves implementing dietary strategies and targeted supplementation, emphasizing key nutrients like vitamin B6, B12, and folate that are crucial for Hcy conversion. Adequate intake of these vitamins, along with betaine supplementation, supports Hcy remethylation. Lifestyle modifications, such as smoking cessation and regular physical activity, complement the nutritional approach to enhance Hcy metabolism. For individuals with HHcy, maintaining a plasma Hcy concentration below 50 μmol/L consistently is vital to lowering the risk of vascular events. Collaboration with healthcare professionals and dietitians is essential for developing personalized dietary plans addressing the specific needs and underlying health conditions. This integrated approach aims to optimize metabolic processes and reduce the associated health risks.

Metabolomics in Severe Aortic Stenosis Reveals Intermediates of Nitric Oxide Synthesis as Most Distinctive Markers

BACKGROUND

Calcific aortic valve disease (CAVD) is a rapidly growing global health problem with an estimated 12.6 million cases globally in 2017 and a 112% increase of deaths since 1990 due to aging and population growth. CAVD may develop into aortic stenosis (AS) by progressive narrowing of the aortic valve. AS is underdiagnosed, and if treatment by aortic valve replacement (AVR) is delayed, this leads to poor recovery of cardiac function, absence of symptomatic improvement and marked increase of mortality. Considering the current limitations to define the stage of AS-induced cardiac remodeling, there is need for a novel method to aid in the diagnosis of AS and timing of intervention, which may be found in metabolomics profiling of patients.

METHODS

Serum samples of nine healthy controls and 10 AS patients before and after AVR were analyzed by untargeted mass spectrometry. Multivariate modeling was performed to determine a metabolic profile of 30 serum metabolites which distinguishes AS patients from controls. Human cardiac microvascular endothelial cells (CMECs) were incubated with serum of the AS patients and then stained for ICAM-1 with Western Blot to analyze the effect of AS patient serum on endothelial cell activation.

RESULTS

The top 30 metabolic profile strongly distinguishes AS patients from healthy controls and includes 17 metabolites related to nitric oxide metabolism and 12 metabolites related to inflammation, in line with the known pathomechanism for calcific aortic valve disease. Nine metabolites correlate strongly with left ventricular mass, of which three show reversal back to control values after AVR. Western blot analysis of CMECs incubated with AS patient sera shows a significant reduction (14%) in ICAM-1 in AS samples taken after AVR compared to AS patient sera before AVR.

CONCLUSION

Our study defined a top 30 metabolic profile with biological and clinical relevance, which may be used as blood biomarker to identify AS patients in need of cardiac surgery. Future studies are warranted in patients with mild-to-moderate AS to determine if these metabolites reflect disease severity and can be used to identify AS patients in need of cardiac surgery.

Uremic Toxins and Vascular Calcification-Missing the Forest for All the Trees

The cardiorenal syndrome relates to the detrimental interplay between the vascular system and the kidney. The uremic milieu induced by reduced kidney function alters the phenotype of vascular smooth muscle cells (VSMC) and promotes vascular calcification, a condition which is strongly linked to cardiovascular morbidity and mortality. Biological mechanisms involved include generation of reactive oxygen species, inflammation and accelerated senescence. A better understanding of the vasotoxic effects of uremic retention molecules may reveal novel avenues to reduce vascular calcification in CKD. The present review aims to present a state of the art on the role of uremic toxins in pathogenesis of vascular calcification. Evidence, so far, is fragmentary and limited with only a few uremic toxins being investigated, often by a single group of investigators. Experimental heterogeneity furthermore hampers comparison. There is a clear need for a concerted action harmonizing and standardizing experimental protocols and combining efforts of basic and clinical researchers to solve the complex puzzle of uremic vascular calcification.

Homocysteine and age-associated disorders

There are numerous theories of aging, a process which still seems inevitable. Aging leads to cancer and multi-systemic disorders as well as chronic diseases. Decline in age- associated cellular functions leads to neurodegeneration and cognitive decline that affect the quality of life. Accumulation of damage, mutations, metabolic changes, failure in cellular energy production and clearance of altered proteins over the lifetime, and hyperhomocysteinemia, ultimately result in tissue degeneration. The decline in renal functions, nutritional deficiencies, deregulation of methionine cycle and deficiencies of homocysteine remethylation and transsulfuration cofactors cause elevation of homocysteine with advancing age. Abnormal accumulation of homocysteine is a risk factor of cardiovascular, neurodegenerative and chronic kidney disease. Moreover, approximately 50% of people, aged 65 years and older develop hypertension and are at a high risk of developing cardiovascular insufficiency and incurable neurodegenerative disorders. Increasing evidence suggests inverse relation between cognitive impairment, cerebrovascular and cardiovascular events and renal function. Oxidative stress, inactivation of nitric oxide synthase pathway and mitochondria dysfunction associated with impaired homocysteine metabolism lead to aging tissue degeneration. In this review, we examine impact of high homocysteine levels on changes observed with aging that contribute to development and progression of age associated diseases.

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.

Epigenetic regulation of aortic remodeling in hyperhomocysteinemia

Hyperhomocysteinemia (HHcy) is prevalent in patients with hypertension and is an independent risk factor for aortic pathologies. HHcy is known to cause an imbalance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs), leading to the accumulation of collagen in the aorta and resulting in stiffness and development of hypertension. Although the exact mechanism of extracellular matrix (ECM) remodeling is unclear, emerging evidence implicates epigenetic regulation involving DNA methylation. Our purpose was to investigate whether 5-aza-2'-deoxycytidine (Aza), a DNA methyltransferase (DNMT1) inhibitor, reduces high blood pressure (BP) by regulating aortic ECM remodeling in HHcy. Wild-type and cystathionine β-synthase (CBS)(+/-) HHcy mice were treated with Aza (0.5 mg/kg body weight). In HHcy mice, Aza treatment normalized the plasma homocysteine (Hcy) level and BP. Thoracic and abdominal aorta ultrasound revealed a reduction in the resistive index and wall-to-lumen ratio. Vascular response to phenylephrine, acetylcholine, and sodium nitroprusside improved after Aza in HHcy mice. Histology showed a marked reduction in collagen deposition in the aorta. Aza treatment decreased the expression of DNMT1, MMP9, TIMP1, and S-adenosyl homocysteine hydrolase (SAHH) and upregulated methylene tetrahydrofolate reductase (MTHFR). We conclude that reduction of DNA methylation by Aza in HHcy reduces adverse aortic remodeling to mitigate hypertension.

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.

Dephosphorylation of circulating human osteopontin correlates with severe valvular calcification in patients with calcific aortic valve disease

CONTEXT

Calcific Aortic Valve Disease (CAVD) is an active pathological process leading to biomineralization of the aortic cusps. We characterized circulating and tissue Osteopontin (OPN) as a biomarker for CAVD.

OBJECTIVES

Here we investigate the post-translational modifications of circulating OPN and correlate the phosphorylation status with the ability to prevent calcification.

METHODS

Circulating OPN levels were estimated in CAVD patients (n = 51) and controls (n = 56). In a subgroup of 27 subjects, OPN was purified and the phosphorylation status analyzed.

RESULTS

Plasma OPN levels were significantly elevated in CAVD patients as compared to the controls and correlates with the aortic valve calcium score. Our study demonstrates that phospho-threonine levels of OPN purified from controls were higher when compared to CAVD subjects, whereas phospho-serine and phospho-tyrosine levels were comparable between the two groups.

CONCLUSION

The dephosphorylation of circulating OPN correlates with severe valvular calcification in patients with CAVD.

Aortic valve disease and treatment: the need for naturally engineered solutions

The aortic valve regulates unidirectional flow of oxygenated blood to the myocardium and arterial system. The natural anatomical geometry and microstructural complexity ensures biomechanically and hemodynamically efficient function. The compliant cusps are populated with unique cell phenotypes that continually remodel tissue for long-term durability within an extremely demanding mechanical environment. Alteration from normal valve homeostasis arises from genetic and microenvironmental (mechanical) sources, which lead to congenital and/or premature structural degeneration. Aortic valve stenosis pathobiology shares some features of atherosclerosis, but its final calcification endpoint is distinct. Despite its broad and significant clinical significance, very little is known about the mechanisms of normal valve mechanobiology and mechanisms of disease. This is reflected in the paucity of predictive diagnostic tools, early stage interventional strategies, and stagnation in regenerative medicine innovation. Tissue engineering has unique potential for aortic valve disease therapy, but overcoming current design pitfalls will require even more multidisciplinary effort. This review summarizes the latest advancements in aortic valve research and highlights important future directions.

Insights into the use of biomarkers in calcific aortic valve disease

Calcific aortic valve disease (CAVD) is the most common acquired valvular disorder in developed countries. CAVD ranges from mild thickening of the valve, known as aortic valve sclerosis (AVSc), to severe impairment of the valve motion, which is termed aortic valve stenosis (AVS). The prevalence of CAVD is nearing epidemic status: its preceding stage, in which there is aortic sclerosis without obstruction of the left ventricular outflow, is present in almost 30% of adults aged over 65 years. As there is no existing medical therapy to treat or slow the progression of CAVD, surgery for advanced disease represents the only available treatment. Aortic valve replacement is the second most frequently performed cardiac surgical procedure after coronary artery bypass grafting, and consequently CAVD represents a major societal and economic burden. The pathophysiological development of CAVD is incompletely defined. At the present time, the major methods for its diagnosis are clinical examination, echocardiography, and cardiac catheterization. Yet, due to the multiple biological pathways leading to CAVD, there are many potential biomarkers that might be suitable for deriving clinically useful information regarding the presence, severity, progression, and prognosis of CAVD. Although at the present time the available data do not permit recommendations for clinicians, they do support a paradigm of screening patients based on multiple biomarkers to provide the information necessary to optimize future therapeutic interventions. This review summarizes the results of several studies investigating the value of potential biomarkers that have been used to predict the severity, progression, and prognosis of CAVD.

Validation of plasma biomarkers in degenerative calcific aortic stenosis

BACKGROUND

Calcific aortic stenosis (CAS) is the most common acquired valvular disorder in industrialized countries. This study investigates the correlation of different known biomarkers for CAS as a first step towards the development of a panel of biomarkers that can be used in prognostic staging.

METHODS

Venous blood samples were obtained from both patients with CAS scheduled for surgery and healthy individuals. Plasma levels of fetuin-A, NT-proBNP, BNP, homocysteine and osteopontin were measured by enzyme-linked immunosorbent assay (ELISA). CAS was measured by echocardiography and was defined as an aortic valve area of less than 2.0 cm(2). Non-paired t-tests were used for comparison.

RESULTS

CAS was present in 33 subjects (mean age 75.9 y) and absent in 11 subjects (mean age 55.36 y). Individuals with CAS exhibited higher plasma levels of NT-proBNP (1.33 versus 0.73 pmol/mL, P < 0.05), BNP fragment (1.47 versus 0.34 ng/mL P < 0.05), and osteopontin (60.79 versus 25.42 ng/mL P < 0.05) compared with controls. Fetuin-A levels were lower in individuals with CAS than in healthy controls (0.25 versus 0.34g/L, P < 0.05). Asymmetric dimethylarginine (ADMA) were lower (1.08 versus 1.1 micromol/L, P > 0.05) while homocysteine levels (20.34 +/- 2.14 versus 19.23 +/- 4.19 P > 0.05) were higher in the CAS patients.

CONCLUSION

This study demonstrates a direct correlation of NT-pro-BNP, BNP, and osteopontin and the presence of CAS, while fetuin A showed an inverse correlation. Plasma ADMA and homocysteine levels were comparable in the CAS patients and healthy individuals. This is the first study in which several biomarkers previously studied independently in patients with CAS have been investigated simultaneously in the same study population.