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

Lipoprotein(a) and Its Autoantibodies in Association with Calcific Aortic Valve Stenosis

Aortic valve stenosis is the most common valvular heart disease in the Western world. Lipoprotein(a) (Lp(a)) is an independent risk factor of coronary heart disease (CHD) and calcific aortic valve stenosis (CAVS). The aim of this study was to assess the role of Lp(a) and its autoantibodies [autoAbs] in CAVS in patients with and without CHD. We included 250 patients (mean age 69 ± 3 years, males 42%) and divided them into three groups. There were two groups of patients with CAVS depending on the presence (group 1) or absence of CHD (group 2). The control group included the patients without CHD or CAVS. According to logistic regression analysis, levels of Lp(a), IgM autoAbs to oxidized Lp(a) (oxLp(a)), and age were independent predictors of CAVS. A concomitant increase in Lp(a) level (≥30 mg/dL) and a decrease in IgM autoAbs concentration (<9.9 lab. Units) are associated with CAVS with an odds ratio (OR) of 6.4, p < 0.01, and with CAVS and CHD with an OR of 17.3, p < 0.001. IgM autoantibodies to oxLp(a) are associated with calcific aortic valve stenosis regardless of Lp(a) concentration and other risk factors. Higher Lp(a) and lower IgM autoantibodies to oxLp(a) levels are associated with a much higher risk of calcific aortic valve stenosis.

The association between aortic valve calcification, cardiovascular risk factors, and cardiac size and function in a general population

To determine the presence and extent of aortic valve calcification (AVC) quantified by non-contrast cardiac computed tomography (NCCT), to determine the association between traditional cardiovascular risk factors and AVC score, and to evaluate the association between AVC and cardiac size and function assessed by echocardiography, in a general population aged 65-75 years. A random sample of 2060 individuals were invited to undergo NCCT through which their AVC score was assessed. Individuals with an AVC score ≥ 300 arbitrary units (AU) were invited for a transthoracic echocardiography together with age-matched controls. Descriptive statistics and multiple regression analyses were performed to identify risk factors associated with AVC and to describe associations between AVC score and echocardiographic findings. Of 2060 individuals invited 664 males and 636 females participated. Among those, 455 (68.5%) of males and 358 (56.3%) of females had AVC scores > 0 AU. The median AVC score was 6 AU (IQR 0-3064). Seventy-seven (11.6%) males and 20 (3.1%) females had an AVC score ≥ 300 AU. In a multiple regression analysis, age, sex, prior cardiovascular disease, smoking, and hypertension were associated with AVC score, while diabetes, hypercholesterolemia and kidney function were not. Individuals with AVC ≥ 300 AU had higher peak and mean aortic valve gradient, smaller indexed aortic valve area, greater left ventricular mass, and larger left atrial (LA) volume. In a random population sample of individuals aged 65-75 years, AVC was common and associated with most known cardiovascular risk factors. AVC ≥ 300 AU was associated with concentric remodeling and LA dilatation.

Aortic Valve Stenosis and Mitochondrial Dysfunctions: Clinical and Molecular Perspectives

Calcific aortic stenosis is a disorder that impacts the physiology of heart valves. Fibrocalcific events progress in conjunction with thickening of the valve leaflets. Over the years, these events promote stenosis and obstruction of blood flow. Known and common risk factors are congenital defects, aging and metabolic syndromes linked to high plasma levels of lipoproteins. Inflammation and oxidative stress are the main molecular mediators of the evolution of aortic stenosis in patients and these mediators regulate both the degradation and remodeling processes. Mitochondrial dysfunction and dysregulation of autophagy also contribute to the disease. A better understanding of these cellular impairments might help to develop new ways to treat patients since, at the moment, there is no effective medical treatment to diminish neither the advancement of valve stenosis nor the left ventricular function impairments, and the current approaches are surgical treatment or transcatheter aortic valve replacement with prosthesis.

Calcific Aortic Valve Stenosis and Atherosclerotic Calcification

PURPOSE OF REVIEW

This review summarizes the pathophysiology of calcific aortic valve stenosis (CAVS) and surveys relevant clinical data and basic research that explain how CAVS arises.

RECENT FINDINGS

Lipoprotein(a) [Lp(a)], lipoprotein-associated phospholipase A2 (Lp-PLA2), oxidized phospholipids (OxPL), autotaxin, and genetic driving forces such as mutations in LPA gene and NOTCH gene seem to play a major role in the development of CAVS. These factors might well become targets of medical therapy in the coming years. CVAS seems to be a multifactorial disease that has much in common with coronary artery disease, mainly regarding lipidic accumulation and calcium deposition. No clinical trials conducted to date have managed to answer the key question of whether Lp(a) lowering and anti-calcific therapies confer a benefit in terms of reducing incidence or progression of CAVS, although additional outcome trials are ongoing.

Oxidized LDL and anti-oxidized LDL antibodies in atherosclerosis - Novel insights and future directions in diagnosis and therapy<sup/>

We provide an up-to-date overview of current topics surrounding oxidized low-density lipoprotein (oxLDL) and its related antibodies in the quest to better identify the individuals at risk of cardiovascular disease and atherosclerotic plaques with unfavorable characteristics. We discuss the potential of oxLDL and anti-oxLDL antibodies as serum biomarkers of cardiovascular disease and emerging studies examining the targeting of arterial oxLDL for imaging and therapeutic delivery.

Low-density lipoprotein oxidation biomarkers in human health and disease and effects of bioactive compounds

Based on the significance of oxidized low-density lipoprotein (LDL) in health and disease, this review focuses on human studies addressing oxidation of LDL, including three lines of biomarkers, (i) ex vivo LDL resistance to oxidation, a "challenge test" model, (ii) circulating oxidized LDL, indicating the "current in vivo status", and (iii) autoantibodies against oxidized LDL as fingerprints of an immune response to oxidized LDL, along with circulating oxysterols and 4-hydroxynonenal as biomarkers of lipid peroxidation. Lipid peroxidation and oxidized LDL are hallmarks in the development of various metabolic, cardiovascular and other diseases. Changes further occur across life stages from infancy to older age as well as in athletes and smokers. Given their responsiveness to targeted nutritional interventions, markers of LDL oxidation have been employed in a rapidly growing number of human studies for more than 2 decades. There is growing interest in foods, which, besides providing energy and nutrients, exert beneficial effects on human health, such as protection of DNA, proteins and lipids from oxidative damage. Any health claim, however, needs to be substantiated by supportive evidence derived from human studies, using reliable biomarkers to demonstrate such beneficial effects. A large body of evidence has accumulated, demonstrating protection of LDL from oxidation by bioactive food compounds, including vitamins, other micronutrients and secondary plant ingredients, which will facilitate the selection of oxidation biomarkers for future human intervention studies and health claim support.