Oxidative stress in children on hemodialysis: value of autoantibodies against oxidized low-density lipoprotein

Systemic Inflammation, Oxidative Stress and Cardiovascular Health in Children and Adolescents: A Systematic Review

Recent studies indicate that cerebrovascular diseases and processes of atherosclerosis originate in the childhood era and are largely influenced by chronic inflammation. Some features of vascular dysfunction in adulthood may even be programmed prenatally via genetic influences and an unfavorable intrauterine milieu. Oxidative stress, defined by an imbalance between the production and generation of reactive oxygen species (ROS) in cells and tissues and the capability of an organism to scavenge these molecules via antioxidant mechanisms, has been linked to adverse cardiovascular health in adults, yet has not been systematically reviewed in the pediatric population. We performed a systematic search as per the PRISMA guidelines in PubMed/Medline and Cochrane Reviews and detected, in total, 1228 potentially eligible pediatric articles on systemic inflammation, oxidative stress, antioxidant use, cardiovascular disease and endothelial dysfunction. The abstracts and full-text manuscripts of these were screened for inclusion and exclusion criteria, and a total of 160 articles were included. The results indicate that systemic inflammation and oxidative stress influence cardiovascular health in many chronic pediatric conditions, including hypertension, obesity, diabetes mellitus types 1 and 2, chronic kidney disease, hyperlipidemia and obstructive sleep apnea. Exercise and diet may diminish ROS formation and enhance the total serum antioxidant capacity. Antioxidant supplementation may, in selected conditions, contribute to the diminution of the oxidative state and improve endothelial function; yet, in many areas, studies provide unsatisfactory results.

Influence of hypercholesterolemia on serum antibodies against oxidized LDL in children and adolescents

BACKGROUND

The oxidation of low-density lipoprotein (LDL; oxLDL) appears to play a key role in the early development of atherosclerosis. Increased serum antibodies against the oxLDL (anti-oxLDL antibodies) have been found in adults with atherosclerotic disease, as well as in healthy adults. The clinical significance and its precise role (atherogenic or atheroprotective), however, have not yet been clarified. This aim of this study was therefore to evaluate anti-oxLDL antibodies in healthy children and adolescents with and without hypercholesterolemia.

METHODS

The study involved 312 subjects, aged 4-18 years, 141 with LDL cholesterol (LDL-C) ≥130 mg/dL and 171 with acceptable LDL-C (<110 mg/dL). Total anti-oxLDL antibodies, total cholesterol, LDL-C and high-density lipoprotein cholesterol, triglycerides, apolipoproteins A1 and B, lipoprotein (a) and high-sensitivity C-reactive protein were measured in fasting serum. The anti-oxLDL antibodies were measured on enzyme-linked immunosorbent assay.

RESULTS

Anti-oxLDL antibodies were similar in the hypercholesterolemia and non-hypercholesterolemia groups. Girls had significantly higher anti-oxLDL antibodies compared with boys. There was no significant correlation of antibodies with age or body mass index. Increased apolipoprotein B was an important factor for lower anti-oxLDL antibodies, while all other parameters had no significant association with anti-oxLDL antibodies.

CONCLUSION

In children and adolescents with hypercholesterolemia, total anti-oxLDL antibodies cannot serve as a marker for risk for atherosclerosis or for future cardiovascular disease.

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.

Effect of serum FGF-23, MGP and fetuin-A on calcium-phosphate metabolism in maintenance hemodialysis patients

This study was aimed to explore the role of serum fibroblast growth factor (FGF)-23, matrix Gla protein (MGP) and fetuin-A in the calcium-phosphate metabolism and their predicting value in coronary artery calcification in maintenance hemodialysis (MHD) patients. This study included 64 patients who receive hemodialysis in our hospital. The serum FGF-23, MGP and fetuin-A were analyzed by enzyme-linked immunosorbent assay (ELlSA). Coronary artery calcification score (CACS) was evaluated by coronary artery computed tomography scan. The 64 patients (30 males, 34 females, 60.6 ± 11.3 years of age) received an average dialysis vintage of 6.88 ± 2.94 years. We divided the CACS into three levels, and 13 (20.31%), 16 (25%), and 35 (54.69%) exhibited a CACS of 0-100, 100-400, and >400, respectively. Dialysis vintage, serum FGF-23, fetuin-A, phosphorus and high-density lipoprotein-C levels were identified as independent variables of CACS by stepwise multiple regression analysis. The area under receiver operating characteristic curve indicated that serum FGF-23 and fetuin-A were useful for identifying CAC in MHD patients. The cut-off value corresponding to the highest Youden's index was serum FGF-23 ≥ 256 pg/mL and fetuin-A ≤ 85 μg/mL, which was defined as the optimal predictors of CAC. Different combinations of serum FGF-23 and fetuin-A in parallel or in series effectively boosted the identification of CAC. The incidence of CAC is high in MHD patients. Serum FGF-23 and fetuin-A levels are closely correlated with CAC.

Hyperlipidemia, oxidative stress, and intima media thickness in children with chronic kidney disease

BACKGROUND

The roles of dyslipidemia and oxidative stress in the early phases of atherosclerosis were tested in children with chronic kidney disease (CKD). Intima media thickness of common carotid arteries (cIMT) is used as a measure of early atherosclerosis.

METHODS

Fifty-two pediatric CKD patients were enrolled in the study (10 with chronic renal failure [CRF], 22 with a renal transplant [RT], 20 with chronic hemodialysis (cHD) patients, and 36 healthy children (control group, CG). Lipid status, oxidative stress, and paraoxonase 1 (PON1) status were assessed. cIMT was measured by ultrasound, adjusted for age and sex, and presented as standard deviation scores (SDS).

RESULTS

Children with CKD had disturbed lipid content, which was most pronounced in cHD children, with higher free cholesterol and triglycerides compared with healthy children. Oxidative stress was markedly increased (malodialdehyde [MDA, μmol/L]: CRF 1.50 ± 0.26, RT 1.55 ± 0.40, cHD 1.77 ± 0.34, CG 0.97 ± 0.33, p < 0.001) and antioxidative defense was compromised (superoxide dismutase [SOD, U/L]: CG 120 ± 21, CRF 84 ± 25, RT 93 ± 12, cHD 119 ± 37, p < 0.001). Multiple linear regression analysis showed that a model that included disease duration, blood pressure, urea, lipid, and oxidative status parameters accounted for more than 90% of the variability of cIMT-SDS.

CONCLUSIONS

Early atherosclerosis in CKD children is caused, at least in part, by dyslipidemia and oxidative stress. Monitoring of vessel wall changes, along with assessment of oxidative stress status and high density lipoprotein (HDL) functionality is necessary to ensure better therapeutic strategies for delaying atherosclerotic changes in their asymptomatic phase.

High prevalence of anti-apolipoprotein/A-1 autoantibodies in maintenance hemodialysis and association with dialysis vintage

Autoantibodies to apolipoprotein/A-1 (anti-ApoA-1 IgG) have pro-atherogenic properties in patients at high cardiovascular risk, but its prevalence in patients with end-stage kidney disease is unknown. The aims of this single-center, cross-sectional study were to assess the prevalence of anti-ApoA-1 antibodies in patients on maintenance hemodialysis (MHD), and to examine its correlation with inflammatory biomarkers related to atherosclerotic plaque vulnerability and dialysis vintage. To this purpose, anti-ApoA-1 IgG levels and the concentrations of interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), metalloproteinase-9 (MMP-9), tumor necrosis factor-α, and C-reactive protein (CRP) were assessed in the sera of 66 MHD patients (mean age: 68 ± 14 years, 36% women, 32% diabetics). Anti-ApoA-1 IgG positivity (defined as a blood value ≥ 97.5(th) percentile of the normal distribution as assessed in healthy blood donors) was 20%. Circulating levels of anti-ApoA-1 IgG correlated positively with dialysis vintage, but not with cardiovascular risk factors or previous cardiovascular events; no significant correlations were found between the anti-ApoA1 IgG levels and circulating levels of IL-6, IL-8, MCP-1, MMP-9, CRP, or low-density lipoprotein-cholesterol. In multivariable linear regression, adjusted for age and sex, only dialysis vintage remained positively and independently associated with anti-ApoA-1 titers (β = 0.05, 95% CI: 0.006; 0.28, P = 0.049). In conclusion, the prevalence of anti-ApoA-1 IgG is raised in the MHD-population, and positively associated with dialysis vintage, a major determinant of cardiovascular outcome. Whether antiApoA-1 antibodies play a role in the pathophysiology of accelerated atherosclerosis in the MHD-population merits further study.