Oxidized LDL, statin use, morbidity, and mortality in patients receiving maintenance hemodialysis

Head-to-Head Comparison of Oxidative Stress Biomarkers for All-Cause Mortality in Hemodialysis Patients

Oxidative stress (OS) presents even in the early chronic kidney disease (CKD) stage and is exacerbated in patients with end-stage renal disease (ESRD) undergoing maintenance hemodialysis (MHD). There is still a debate over the association between oxidative stress and mortality. Our study aims to compare head-to-head the prognostic value of different oxidative markers for all-cause mortality in hemodialysis (HD) patients. We thus enrolled 347 patients on HD in this prospective study. Four OS biomarkers were measured (carbonyl proteins, myeloperoxidase (MPO), advanced oxidation protein products (AOPPs), and oxidized low-density lipoprotein (ox-LDL)). During the 60-month follow-up period, 9 patients have been lost to follow-up and 168 (48.4%) patients died. Concerning the oxidative stress (ox-stress) byproducts, carbonyl proteins were lower in survivors (105.40 ng/mL (IQR 81.30−147.85) versus 129.65 ng/mL (IQR 93.20−180.33); p < 0.001), with similar results for male patients (103.70 ng/mL (IQR 76.90−153.33) versus 134.55 ng/mL (IQR 93.95−178.68); p = 0.0014). However, there are no significant differences in MPO, AOPP, and ox-LDL between the two groups. Kaplan−Meier survival analysis indicated that patients in the higher carbonyl proteins concentration (>117.85 ng/mL group) had a significantly lower survival rate (log-rank test, p < 0.001). Univariate Cox regression analysis showed a positive correlation between carbonyl proteins and all-cause mortality in the higher and lower halves. Even after adjustment for conventional risk factors, it remained a statistically significant predictor of an increased risk of death in MHD. Univariate Cox regression analysis of MPO showed that continuous MPO and Log MPO were significantly associated with all-cause mortality, except for binary MPO (divided according to the median of MPO). Multivariate Cox analysis for MPO showed that the mortality prediction remains significant after adjusting for multiple factors. In conclusion, not all ox-stress biomarkers predict all-cause mortality in HD patients to a similar extent. In the present study, carbonyl proteins and MPO are independent predictors of all-cause mortality in HD patients, whereas AOPPs and oxLDL are clearly not associated with all-cause mortality in HD patients.

The role of inflammation and the possibilities of inflammation reduction to prevent cardiovascular events

Chronic systemic inflammation is a risk factor for cardiovascular (CV) disease (CVD). Whether this relationship extends to subclinical inflammation, quantified by values of circulating markers associated with inflammation in the high range of the normal interval, remains debatable. This narrative review evaluates evidence exploring this relationship. A review of pharmacological and non-pharmacological interventions, including diet and lifestyle strategies, supplements, nutraceuticals, and other natural substances aimed at reducing inflammation was also conducted, since few reviews have synthesized this literature. PubMed and EMBASE were used to search the literature and several well-studied triggers of inflammation [oxidized LDL, Lp(a), as well as C-reactive protein (CRP)/high-sensitivity CRP (hs-CRP)] were included to increase sensitivity and address the lack of existing reviews summarizing their influence in the context of inflammation. All resulting references were assessed. Overall, there is good data supporting associations between circulating hs-CRP and CV outcomes. However, the same was not seen in studies evaluating triggers of inflammation, such as oxidized LDL or Lp(a). There is also insufficient evidence showing treatments to target inflammation and lead to reductions in hs-CRP result in improvements in CV outcomes, particularly in those with normal baseline levels of hs-CRP. Regarding pharmacological interventions, statins, bempedoic acid, and apabetalone significantly reduce circulating hs-CRP, unlike PCSK-9 inhibitors. A variety of natural substances and vitamins were also evaluated and none reduced hs-CRP. Regarding non-pharmacological interventions, weight loss was strongly associated with reductions in circulating hs-CRP, whereas various dietary interventions and exercise regimens were not, unless accompanied by weight loss.

The lipid paradox in neuroprogressive disorders: Causes and consequences

Chronic systemic inflammation is associated with an increased risk of cardiovascular disease in an environment of low low-density lipoprotein (LDL) and low total cholesterol and with the pathophysiology of neuroprogressive disorders. The causes and consequences of this lipid paradox are explored. Circulating activated neutrophils can release inflammatory molecules such as myeloperoxidase and the pro-inflammatory cytokines interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha. Since activated neutrophils are associated with atherosclerosis and cardiovascular disease and with major depressive disorder, bipolar disorder and schizophrenia, it seems reasonable to hypothesise that the inflammatory molecules released by them may act as mediators of the link between systemic inflammation and the development of atherosclerosis in neuroprogressive disorders. This hypothesis is tested by considering the association at a molecular level of systemic inflammation with increased LDL oxidation; increased small dense LDL levels; increased lipoprotein (a) concentration; secretory phospholipase A₂ activation; cytosolic phospholipase A₂ activation; increased platelet activation; decreased apolipoprotein A1 levels and function; decreased paroxonase-1 activity; hyperhomocysteinaemia; and metabolic endotoxaemia. These molecular mechanisms suggest potential therapeutic targets.

Mechanisms and Modulation of Oxidative/Nitrative Stress in Type 4 Cardio-Renal Syndrome and Renal Sarcopenia

Chronic kidney disease (CKD) is a public health problem and a recognized risk factor for cardiovascular diseases (CVD). CKD could amplify the progression of chronic heart failure leading to the development of type 4 cardio-renal syndrome (T4CRS). The severity and persistence of heart failure are strongly associated with mortality risk in T4CRS. CKD is also a catabolic state leading to renal sarcopenia which is characterized by the loss of skeletal muscle strength and physical function. Renal sarcopenia also promotes the development of CVD and increases the mortality in CKD patients. In turn, heart failure developed in T4CRS could result in chronic muscle hypoperfusion and metabolic disturbances leading to or aggravating the renal sarcopenia. The interplay of multiple factors (e.g., comorbidities, over-activated renin-angiotensin-aldosterone system [RAAS], sympathetic nervous system [SNS], oxidative/nitrative stress, inflammation, etc.) may result in the progression of T4CRS and renal sarcopenia. Among these factors, oxidative/nitrative stress plays a crucial role in the complex pathomechanism and interrelationship between T4CRS and renal sarcopenia. In the heart and skeletal muscle, mitochondria, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, uncoupled nitric oxide synthase (NOS) and xanthine oxidase are major ROS sources producing superoxide anion (O2^·−) and/or hydrogen peroxide (H₂O₂). O2^·− reacts with nitric oxide (NO) forming peroxynitrite (ONOO⁻) which is a highly reactive nitrogen species (RNS). High levels of ROS/RNS cause lipid peroxidation, DNA damage, interacts with both DNA repair enzymes and transcription factors, leads to the oxidation/nitration of key proteins involved in contractility, calcium handling, metabolism, antioxidant defense mechanisms, etc. It also activates the inflammatory response, stress signals inducing cardiac hypertrophy, fibrosis, or cell death via different mechanisms (e.g., apoptosis, necrosis) and dysregulates autophagy. Therefore, the thorough understanding of the mechanisms which lead to perturbations in oxidative/nitrative metabolism and its relationship with pro-inflammatory, hypertrophic, fibrotic, cell death and other pathways would help to develop strategies to counteract systemic and tissue oxidative/nitrative stress in T4CRS and renal sarcopenia. In this review, we also focus on the effects of some well-known and novel pharmaceuticals, nutraceuticals, and physical exercise on cardiac and skeletal muscle oxidative/nitrative stress in T4CRS and renal sarcopenia.

Oxidized Low-Density Lipoprotein Serum Concentrations and Cardiovascular Morbidity in End Stage of Renal Disease

Introduction: Oxidized low-density lipoprotein (ox-LDL) is considered a main biomarker of oxidative stress, a common characteristic in end stage renal disease. We examined the relationship between ox-LDL serum concentrations and cardiovascular disease in permanent hemodiafiltration therapy patients. Methods: Ox-LDL values were measured by ELISA and were corrected for LDL-cholesterol (LDL-C) in 96 participants and in 45 healthy control subjects. We performed chi-square tests and adjusted models for the role of ox-LDL on cardiovascular morbidity including coronary artery disease, left ventricular hypertrophy, systolic, diastolic dysfunction and peripheral arterial disease. Results: ox-LDL/LDL-C values were significantly higher in patients than in control group (p = 0.02), due to increased ox-LDL serum levels rather than to low LDL-C. The unadjusted relationship between high ox-LDL/LDL-C and low ejection fraction was found significant (x2 = 9.04, p = 0.003), although the association with the other cardiovascular manifestations was found non-significant. In the adjusted model for the prediction of systolic cardiac dysfunction, high ox-LDL/LDL-C, old age and non-administration of vitamin D supplementation during dialysis session were found to be significant predictors after adjustment to the confounder. Moreover, the association between systolic cardiac dysfunction and non-administration of vitamin D derivatives during dialysis sessions was found significant (x2 = 6.9, p = 0.008). Conclusions: This study showed a significant association between high ox-LDL and systolic cardiac dysfunction in permanent hemodiafiltration therapy patients. This relationship seems to be influenced by aging and pharmaceutical therapy during dialysis sessions, including vitamin D derivatives.

Oxidized Low-Density Lipoprotein Serum Concentrations and Cardiovascular Morbidity in End Stage of Renal Disease

INTRODUCTION

Oxidized low-density lipoprotein (ox-LDL) is considered a main biomarker of oxidative stress, a common characteristic in end stage renal disease. We examined the relationship between ox-LDL serum concentrations and cardiovascular disease in permanent hemodiafiltration therapy patients.

METHODS

Ox-LDL values were measured by ELISA and were corrected for LDL-cholesterol (LDL-C) in 96 participants and in 45 healthy control subjects. We performed chi-square tests and adjusted models for the role of ox-LDL on cardiovascular morbidity including coronary artery disease, left ventricular hypertrophy, systolic, diastolic dysfunction and peripheral arterial disease.

RESULTS

ox-LDL/LDL-C values were significantly higher in patients than in control group (p = 0.02), due to increased ox-LDL serum levels rather than to low LDL-C. The unadjusted relationship between high ox-LDL/LDL-C and low ejection fraction was found significant (x² = 9.04, p = 0.003), although the association with the other cardiovascular manifestations was found non-significant. In the adjusted model for the prediction of systolic cardiac dysfunction, high ox-LDL/LDL-C, old age and non-administration of vitamin D supplementation during dialysis session were found to be significant predictors after adjustment to the confounder. Moreover, the association between systolic cardiac dysfunction and non-administration of vitamin D derivatives during dialysis sessions was found significant (x² = 6.9, p = 0.008).

CONCLUSIONS

This study showed a significant association between high ox-LDL and systolic cardiac dysfunction in permanent hemodiafiltration therapy patients. This relationship seems to be influenced by aging and pharmaceutical therapy during dialysis sessions, including vitamin D derivatives.

Oxidative Stress in Kidney Diseases: The Cause or the Consequence?

Exaggerated oxidative stress (OS) is usually considered as a disturbance in regular function of an organism. The excessive levels of OS mediators may lead to major damage within the organism’s cells and tissues. Therefore, the OS-associated biomarkers may be considered as new diagnostic tools of various diseases. In nephrology, researchers are looking for alternative methods replacing the renal biopsy in patients with suspicion of chronic kidney disease (CKD). Currently, CKD is a frequent health problem in world population, which can lead to progressive loss of kidney function and eventually to end-stage renal disease. The course of CKD depends on the primary disease. It is assumed that one of the factors influencing the course of CKD might be OS. In the current work, we review whether monitoring the OS-associated biomarkers in nephrology patients can support the decision-making process regarding diagnosis, prognostication and treatment initiation.

Statin treatment in dialysis patients after acute myocardial infarction improves overall mortality

While statins are widely accepted as a keystone for secondary prevention of cardiovascular disease in the general population, statin treatment in chronic renal failure is still debated. Statins have shown no benefit on cardiovascular outcomes in 4D, AURORA, and SHARP trials conducted in patients on dialysis. However, no study has yet compared statin treatment after acute myocardial infarction in end-stage renal disease (ESRD) patients. Statin treatment significantly decreases overall mortality in ESRD patients with acute myocardial infarction compared to the non-statin group. This is more prominent in the cardiac shock patient subgroup. The results are compatible with other studies, supporting a measurable benefit from statins in ESRD patients. There is no clear consensus on statin treatment in dialysis patients. The study by Chung et al. published in this issue of Atherosclerosis was conducted in a large patients' pool, with a long follow-up period [1]. Authors have reported an important result supporting statin treatment in dialysis patients after acute myocardial infarction.