Plasma Lipoprotein Abnormalities in Hemodialysis Patients—Clinical Implications and Therapeutic Guidelines

Dose-response relationship between lipids and all-cause mortality in the dialysis population: a meta-analysis

BACKGROUND

The use of lipid-lowering drugs in the dialysis population has been controversial and there is no target for the dialysis population.

OBJECTIVES

To elucidate the dose-response relationship between lipids and all-cause mortality in the dialysis population.

METHODS

Computer searches of PubMed, Embase, Web of Science, CNKI, and Wanfang. Data were conducted to collect published cohort studies on lipids and all-cause mortality in the dialysis population from home and abroad up to February 2023. Meta-analysis was applied to calculate the combined effect size (Hazard ratio) and its 95% confidence interval and dose-response relationship by applying Stata17.0.

RESULTS

A total of 11 publications with a cumulative total of 106,808 individuals were included. All-cause mortality was statistically different between the highest dose total cholesterol (TC) group and the low TC group (HR = 0.82, 95% CI = 0.75-0.90, P < 0.05). The TC range for lower all-cause mortality is > 140.5 mg/dL, and on this basis, TC in the range of 180-220 mg/dL may have a better prognosis for dialysis population. There was a nonlinear relationship between Non-high-density lipoprotein cholesterol (NHDL-C) cholesterol and all-cause mortality, with no statistical difference between the high and low dose group. In contrast, Low-density lipoprotein cholesterol (LDL-C) masked its association with all-cause mortality due to changes in death spectrum, differences in relative time risks, and other factors. In the 50-450 mg/dL range, all-cause mortality in the dialysis population was positively associated with triglycerides (TG), with a 2.5% increase in all-cause mortality per 50 mg/dL increase in TG (HR = 1.025, 95% CI = 1.003-1.048, P = 0.01).

CONCLUSION

TC is a target for monitoring the dialysis population, which has the lowest all-cause mortality in the range of 180-220 mg/dL. However, NHDL-C and LDL-C monitoring is not clinically meaningful. Increased TG can contribute to the risk of higher all-cause mortality in dialysis patients.

Pomegranate juice improves cardiometabolic risk factors, biomarkers of oxidative stress and inflammation in hemodialysis patients: a randomized crossover trial

BACKGROUND

Pomegranate has antioxidant, cardioprotective and anti-inflammatory properties. We designed a crossover study aimed at determining if consumption of pomegranate juice (PJ) improves lipid profile and oxidative and inflammatory biomarkers of hemodialysis patients. Forty-one hemodialysis patients were randomly assigned to one of two groups: PJ-treated group receiving 100 mL of natural PJ immediately after their dialysis session three times a week and the control group receiving the usual care. After 8 weeks, a 4-week washout period was established and then the role of the groups was exchanged. Lipid profile, blood pressure and oxidative and inflammatory biomarkers were measured before and after each sequence.

RESULTS

Based on the results of intention-to-treat analysis, triglycerides were decreased in PJ condition and increased in the controls. Conversely, high-density lipoprotein cholesterol was increased in PJ and decreased in the control group. Total and low-density lipoprotein cholesterol did not significantly change in either condition. Systolic and diastolic blood pressure significantly decreased in PJ condition. Total antioxidant capacity increased in PJ condition (P < 0.001) and decreased in the controls (P < 0.001). Conversely, malondialdehyde and interleukin-6 decreased in PJ (P < 0.001) and increased in the control group (P ≤ 0.001). The changes of these biomarkers were significantly different between the two conditions.

CONCLUSIONS

Eight-week PJ consumption showed beneficial effects on blood pressure, serum triglycerides, high-density lipoprotein cholesterol, oxidative stress and inflammation in hemodialysis patients. © 2019 Society of Chemical Industry.

Cyanate Induces Oxidative Stress Injury and Abnormal Lipid Metabolism in Liver through Nrf2/HO-1

Chronic kidney disease (CKD) is problem that has become one of the major issues affecting public health. Extensive clinical data suggests that the prevalence of hyperlipidemia in CKD patients is significantly higher than in the general population. Lipid metabolism disorders can damage the renal parenchyma and promote the occurrence of cardiovascular disease (CVD). Cyanate is a uremic toxin that has attracted widespread attention in recent years. Usually, 0.8% of the molar concentration of urea is converted into cyanate, while myeloperoxidase (MPO) catalyzes the oxidation of thiocyanate to produce cyanate at the site of inflammation during smoking, inflammation, or exposure to environmental pollution. One of the important physiological functions of cyanate is protein carbonylation, a non-enzymatic post-translational protein modification. Carbamylation reactions on proteins are capable of irreversibly changing protein structure and function, resulting in pathologic molecular and cellular responses. In addition, recent studies have shown that cyanate can directly damage vascular tissue by producing large amounts of reactive oxygen species (ROS). Oxidative stress leads to the disorder of liver lipid metabolism, which is also an important mechanism leading to cirrhosis and liver fibrosis. However, the influence of cyanate on liver has remained unclear. In this research, we explored the effects of cyanate on the oxidative stress injury and abnormal lipid metabolism in mice and HL-7702 cells. In results, cyanate induced hyperlipidemia and oxidative stress by influencing the content of total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), superoxide dismutase (SOD), catalase (CAT) in liver. Cyanate inhibited NF-E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and the phosphorylation of adenosine 5'monophosphate-activated protein kinase (AMPK), activated the mTOR pathway. Oxidative stress on the cells reduced significantly by treating with TBHQ, an antioxidant, which is also an activator of Nrf2. The activity of Nrf2 was rehabilitated and phosphorylation of mTOR decreased. In conclusion, cyanate could induce oxidative stress damage and lipid deposition by inhibiting Nrf2/HO-1 pathway, which was rescued by inhibitor of Nrf2.

Dietary Unsaturated Fatty Acids Modulate Maternal Dyslipidemia-Induced DNA Methylation and Histone Acetylation in Placenta and Fetal Liver in Rats

The present study assessed the role of dietary unsaturated fatty acids in maternal dyslipidemia-induced DNA methylation and histone acetylation in placenta and fetal liver and accumulation of lipids in the fetal liver. Weanling female Wistar rats were fed control and experimental diets for 2 months, mated, and continued on their diets during pregnancy. At gestation days of 18-20, rats were euthanized to isolate placenta and fetal liver. DNA methylation, DNA methyl transferase-1 (DNMT1) activity, acetylation of histones (H2A and H2B), and histone acyl transferase (HAT) activity were evaluated in placenta and fetal liver. Fetal liver lipid accumulation and activation of peroxisome proliferator-activated receptor-α (PPAR-α) were assessed. Maternal dyslipidemia caused significant epigenetic changes in placenta and fetal liver. In the placenta, (1) global DNA methylation increased by 37% and DNMT1 activity by 86%, (2) acetylated H2A and H2B levels decreased by 46% and 24% respectively, and (3) HAT activity decreased by 39%. In fetal liver, (1) global DNA methylation increased by 52% and DNMT1 activity by 78%, (2) acetylated H2A and H2B levels decreased by 28% and 26% respectively, and (3) HAT activity decreased by 37%. Maternal dyslipidemia caused a 4.75-fold increase in fetal liver triacylglycerol accumulation with a 78% decrease in DNA-binding ability of PPAR-α. Incorporation of dietary unsaturated fatty acids in the maternal high-fat diet significantly (p < 0.05) modulated dyslipidemia-induced effects in placenta and fetal liver. Eicosapentaenoic acid (EPA, 20:5n-3) + docosahexaenoic acid (DHA, 22:6n-3) exhibited a profound effect followed by alpha-linolenic acid (ALA, 18:3n-3) than linoleic acid (LNA, 18:2n-6) in modulating the epigenetic parameters in placenta and fetal liver.

What's the Optimal Lipids Level for Dialysis Patients? A Cohort Study from a Chinese Dialysis Center in a University Hospital

BACKGROUND

With lipid level being a major contributing factor for cardiovascular health, the high cardiovascular mortality among dialysis patients has raised substantial concerns in regard to the optimal lipid level in these patient population.

OBJECTIVE

To explore the optimal lipid level for the survival of dialysis patients.

METHODS

The lipid profile was measured for each patient. All participants were followed throughout the course of the study. Cox proportional hazards analysis was performed to analyze the prognostic value of lipid level on the survival of these patients.

RESULTS

In our study that included 311 stable maintenance dialysis patients, 54.98% of the participants had LDL-C level ≥100 mg/dl and 82.91% of the patients with triglycerides ≥200 mg/dl had non-HDL level ≥130 mg/dl. During the follow-up period of 48.0 (18.0, 55.5) months, 149 (47.91%) participants died. Among those who died, 59 patients died of cardiovascular disease (CVD) and 33 patients died of ischemic CVD (12.0, 4.7, and 2.7 events per 100 patient-years, respectively). Patients with LDL-C 100-130 mg/dl or non-HDL 130-160 mg/dl had a lower all-cause mortality rate than those who did not meet these criteria. After adjusting for the traditional and ESRD-related risk factors, non-HDL was found to be the independent risk factor for the all-cause mortality. Compared to those patients with non-HDL 130-160 mg/dl, patients with non-HDL <100 mg/dl, 100-130 mg/dl, 160-190 mg/dl, or ≥190 mg/dl all had higher all-cause mortality: HR (95% CI) 3.207 (1.801, 5.713), 2.493 (1.485, 4.184), 2.476 (1.423, 4.307), and 1.917 (1.099, 3.345), respectively. There were no differences in nutrition, comorbidity, and inflammation indices among the patients with different non-HDL groups. However, patients with non-HDL of 130-160 mg/dl had the lowest corrected calcium and calcium phosphate product values as compared with other non-HDL groups.

CONCLUSION

Our study demonstrated that non-HDL 130-160 mg/dl might be the most appropriate lipid level in our dialysis patients. Our follow-up data also showed that patients with higher lipid level had poorer prognosis, just as in the general population.

Use of vitamin D receptor activator, incident cardiovascular disease and death in a cohort of hemodialysis patients

The use of vitamin D receptor activators (VDRAs) is an independent predictor of a lower risk of death from cardiovascular disease (CVD) in patients with chronic kidney disease (CKD). We examined whether the use of VDRAs and other CKD-mineral bone disorder (MBD)-related factors are associated with incident CVD or death after CVD in hemodialysis patients. This is a historical cohort study of 37 690 prevalent hemodialysis patients without previous history of CVD at the end of 2004 extracted from a nationwide registry in Japan. The key exposure was the use of VDRAs, and the outcomes were incident CVD (myocardial infarction, cerebral infarction, cerebral hemorrhage, and sudden death) and death after CVD during the 1-year follow-up. VDRAs were used in 57% of the subjects at baseline. We identified 2433 patients with incident CVD and 397 deaths after the events. In multivariate logistic regression models, independent predictors of incident CVD were non-use of VDRA, higher intact PTH, non-use of calcium-based phosphate-binder, and non-use of non-calcium-based phosphate binder. Risk of death after CVD was not significantly associated with VDRA, whereas it was lower in those with lower corrected calcium, and the risk was higher in those with higher phosphate and in non-users of calcium-based phosphate binders. The use of VDRAs was associated with a lower risk of incident CVD but not with death after CVD in this large cohort of hemodialysis patients. The CKD-MBD-related predictors of poor outcomes are associated with the risk of incident CVD, the risk of death after CVD, or both.

Oxidised LDL/LDL-cholesterol ratio and coronary artery calcification in haemodialysis patients

BACKGROUND AND AIMS

Serum malondialdehyde-modified low-density lipoprotein (MDA-LDL) and MDA-LDL/LDL-cholesterol (LDL-c) ratio are risk factors for arteriosclerosis and cardiovascular disease (CVD). However, no information is available on these parameters or their associations with coronary artery calcification (CAC) in haemodialysis (HD) patients.

METHODS AND RESULTS

Fifty-seven HD patients and 26 control subjects were included in this cross-sectional study. Serum MDA-LDL concentrations and MDA-LDL/LDL-c ratios were examined. HD patients had significantly higher MDA-LDL/LDL-c ratios than the controls (105.1 ± 27.5 vs. 81.4 ± 18.9 mU/mg, P < 0.001); however, there was no significant difference in serum MDA-LDL levels between the 2 groups. CAC scores were examined only in HD patients and their possible associations with the clinical/laboratory data were analysed. Analysis of HD patients showed that MDA-LDL/LDL-c ratio has an association with presence of CVD, CAC score, HD duration, MDA-LDL, or haemoglobin A1C. In addition, the CAC score was positively correlated with serum MDA-LDL level (P = 0.048) and MDA-LDL/LDL-c ratio (P = 0.006). Furthermore, multivariate logistic regression analysis showed that MDA-LDL/LDL-c ratio (β = 0.04, P = 0.003) and HD duration (β = 0.16, P = 0.007) were independently associated with CAC score.

CONCLUSION

The MDA-LDL/LDL-c ratio of HD patients was significantly higher than that of non-HD subjects and was independently associated with the CAC score. Therefore, this ratio could be an important risk factor for CAC in HD patients.

Does methylmercury-induced hypercholesterolemia play a causal role in its neurotoxicity and cardiovascular disease?

Methylmercury (MeHg) is an environmental pollutant that biomagnifies throughout the aquatic food chain, thus representing a toxicological concern for humans subsiding on fish for their dietary intake. Although the developing brain is considered the critical target organ of MeHg toxicity, recent evidence indicates that the cardiovascular system may be the most sensitive in adults. However, data on the mechanisms mediating MeHg-induced cardiovascular toxicity are scarce. Based on the close relationship between cardiovascular disease and dyslipidemia, this study was designed to investigate the effects of long-term MeHg exposure on plasma lipid levels in mice, as well as their underlying mechanisms and potential relationships to MeHg-induced neurotoxicity. Our major finding was that long-term MeHg exposure induced dyslipidemia in rodents. Specifically, Swiss and C57BL/6 mice treated for 21 days with a drinking solution of MeHg (40 mg/l, ad libitum) diluted in tap water showed increased total and non-HDL plasma cholesterol levels. MeHg-induced hypercholesterolemia was also observed in low-density lipoprotein receptor knockout (LDLr⁻/⁻) mice, indicating that this effect was not related to decreased LDLr-mediated cholesterol transport from blood to other tissues. Although the hepatic synthesis of cholesterol was unchanged, significant signs of nephrotoxicity (glomerular shrinkage, tubular vacuolization, and changed urea levels) were observed in MeHg-exposed mice, indicating that the involvement of nephropathy in MeHg-induced lipid dyshomeostasis may not be ruled out. Notably, Probucol (a lipid-lowering drug) prevented the development of hypercholesterolemia when coadministered with MeHg. Finally, hypercholesterolemic LDLr⁻/⁻ mice were more susceptible to MeHg-induced cerebellar glial activation, suggesting that hypercholesterolemia in itself may pose a risk factor in MeHg-induced neurotoxicity. Overall, based on the strong and graded positive association between total as well as LDL cholesterol and risk of cardiovascular diseases, our data support the concept of MeHg-induced cardiovascular toxicity.

Serum non-high-density lipoprotein cholesterol (non-HDL-C) levels and cardiovascular mortality in chronic hemodialysis patients

BACKGROUND

Non-high-density lipoprotein cholesterol (non-HDL-C) has been proposed as a predictor of cardiovascular disease (CVD) in the general population. The aim of this study was to evaluate the utility of non-HDL-C in predicting CV mortality in chronic hemodialysis (HD) patients.

METHODS

We calculated the serum non-HDL-C level of 259 HD patients by subtracting their HDL-C levels from their total cholesterol. Cox proportional hazards models were used to estimate the hazards ratio (HR) for CV mortality and the 95% confidence interval (CI). A receiver-operating characteristic (ROC) analysis was performed to estimate the relationship between sensitivity and specificity of a diagnostic parameter.

RESULTS

There were 44 deaths (17.0%) during the follow-up period, 33 (12.7%) of which were due to CVD. A multivariate Cox analysis with adjustments for age, diabetes, dialysis vintage, systolic blood pressure, serum albumin, and lipid levels showed that non-HDL-C was an independent predictor of CV mortality (HR 1.015, 95% CI 1.004-1.025, p = 0.0083). An ROC analysis showed that the plots of the non-HDL-C levels yielded significant specificity and sensitivity for predicting the risk of CVD mortality in HD patients [area under the curve (AUC) 0.62416; p = 0.0366; cutoff value 111.0 mg/dl]. The Kaplan-Meier survival curves of HD patients showed significant differences in CV mortality according to their tertiles with respect to serum non-HDL-C levels (p = 0.0165).

CONCLUSION

The results of this study suggest that serum non-HDL-C level is a significant CV mortality predictor of chronic HD patients.

Non-high-density lipoprotein cholesterol and its correlation with anthropometric markers of cardiovascular risk in hemodialysis

INTRODUCTION

Non-high-density lipoprotein cholesterol (non-HDL-c) may be a better indicator of atherogenicity in the hemodialysis population.

PURPOSE

To investigate the correlation of non-HDL-c with anthropometric measurements associated to cardiovascular risk, such as body mass index, waist circumference, waist-to-height ratio, waist-to-height(2) ratio, and waist-to-hip circumference ratio.

METHODS

We evaluated anthropometric markers and lipids in 86 hemodialysis patients, and the correlation between them was investigated.

RESULTS

Non-HDL-c had a positive correlation with body mass index (r = 0.273; P = .01), waist circumference (r = 0.375; P = .000), waist-to-height ratio (r = 0.333; P = .002), waist-to-height(2) ratio (r = 0.270; P = .012), and waist-to-hip circumference ratio (r = 0.356; P = .001).

CONCLUSIONS

This study detected a positive and significant correlation between non-HDL-c, but not low-density lipoprotein cholesterol, and the anthropometric cardiovascular risk indexes. We could suggest that non-HDL-c can be used as a cardiovascular risk factor indicator among dialysis patients.

Protein oxidative stress and dyslipidemia in dialysis patients

Our aim was to investigate and determine the associations between oxidative stress (OS), dyslipidemia and inflammation in patients treated with continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis (HD) using observational cross-sectional study. Twenty patients in CAPD and 48 in HD for at least 8 weeks and aged ≥18 years were included in the study. Individuals with malignant or acute inflammatory disease were excluded. A control group of 17 healthy individuals was also recruited. The biochemical parameter evaluations were analyzed using colorimetric kits for albumin, serum glucose, total cholesterol (TC) and lipid fractions. To determine the inflammatory status, CRP, IL-6 and TNF-α were analyzed by automated chemiluminescence kits. Plasma advanced oxidation protein products (AOPP) were determined by spectrophotometry. Mean AOPP levels were significantly higher for the HD group compared to the control, and there was no difference in AOPP concentrations between the control and CAPD groups. Dialysis patients had levels of inflammatory parameters higher than controls, and showed a high prevalence of patients with dyslipidemia, especially in CAPD. In the HD group, AOPP was positively correlated with triglycerides (TG) and inversely associated with HDL. Also the HD group was observed to have negative associations between TNF-α and HDL, LDL and TC. In the CAPD group, CRP was inversely correlated with HDL. Hemodialysis patients had increased protein OS and associations of inflammation and dyslipidemia were also observed in these dialysis groups. A more detailed characterization of the relations between oxidative stress and other more traditional risk factors has therapeutic importance, since cardiovascular diseases are the leading cause of death among dialysis patients.

Polymorphisms of pon1 and pon2 genes in hemodialyzed patients

OBJECTIVES

Q192R, L55M and -108C>T polymorphisms of pon1 gene affect PON1 paraoxonase activity while S311C polymorphism of pon2 gene might be associated with coronary heart disease. The aims of this study were to determine the frequencies of Q192R, L55M, -108C>T and S311C polymorphisms in hemodialyzed patients and to examine the relationship between pon1 gene polymorphisms and PON1 paraoxonase activity in those patients.

DESIGN AND METHODS

The study included 238 control subjects and 263 hemodialyzed patients.

RESULTS

PON1 paraoxonase activity was lower in patients. Genotype frequencies were different between two compared groups only for L55M polymorphism, with control group having higher frequency of MM genotype. Polymorphisms of pon1 gene were associated with significant variation in PON1 paraoxonase activity in both study groups.

CONCLUSION

Our results suggest that Q192R, L55M and -108C>T polymorphisms are not by itself the causal factors leading to the lower PON1 paraoxonase activity in hemodialyzed patients.

Elevated non-high-density lipoprotein cholesterol (non-HDL-C) predicts atherosclerotic cardiovascular events in hemodialysis patients

BACKGROUND AND OBJECTIVES

Dialysis patients show "reverse causality" between serum cholesterol and mortality. No previous studies clearly separated the risk of incident cardiovascular disease (CVD) and the risk of death or fatality after such events. We tested a hypothesis that dyslipidemia increases the risk of incident atherosclerotic CVD and that protein energy wasting (PEW) increases the risk of fatality after CVD events in hemodialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was an observational cohort study in 45,390 hemodialysis patients without previous history of myocardial infarction (MI), cerebral infarction (CI), or cerebral bleeding (CB) at the end of 2003, extracted from a nationwide dialysis registry in Japan. Outcome measures were new onsets of MI, CI, CB, and death in 1 year.

RESULTS

The incidence rates of MI, CI, and CB were 1.43, 2.53, and 1.01 per 100 person-years, and death rates after these events were 0.23, 0.21, and 0.29 per 100 person-years, respectively. By multivariate logistic regression analysis, incident MI was positively associated with non-HDL cholesterol (non-HDL-C) and inversely with HDL cholesterol (HDL-C). Incident CI was positively associated with non-HDL-C, whereas CB was not significantly associated with these lipid parameters. Among the patients who had new MI, CI, and/or CB, death risk was not associated with HDL-C or non-HDL-C, but with higher age, lower body mass index, and higher C-reactive protein levels.

CONCLUSIONS

In this hemodialysis cohort, dyslipidemia was associated with increased risk of incident atherosclerotic CVD, and protein energy wasting/inflammation with increased risk of death after CVD events.

Dyslipidemia associated with chronic kidney disease

Cardiovascular disease is a major cause of morbidity and mortality in patients with impaired renal function. Dyslipidemia has been established as a well-known traditional risk factor for cardiovascular disease (CVD) in the general population and it is well known that patients with chronic kidney disease (CKD) exhibit significant alterations in lipoprotein metabolism. In this review, the pathogenesis and treatment of CKD-induced dyslipidemia are discussed. Studies on lipid abnormalities in predialysis, hemodialysis and peritoneal dialysis patients are analyzed. In addition, the results of the studies that tested the effects of the hypolipidemic drugs on cardiovascular morbidity and mortality in patients with CKD are reported.

Frequency of cardiovascular risk factors and metabolic syndrome in patients with chronic kidney disease

OBJECTIVE

Metabolic syndrome is a clustering of cardio-metabolic risk factors. Cardiovascular disease is the main cause of morbidity and mortality in end-stage renal disease. The aim of this study was to elucidate the frequency of traditional and novel cardiovascular and metabolic syndrome risk factors in patients with chronic kidney disease. Identification of these risk factors will allow for precautions to be taken earlier to prevent cardiovascular diseases and metabolic syndrome in chronic kidney disease patients.

METHODS

A total of 214 patients (91 females, 123 males, mean age 56.1 ± 14.4 years) with chronic kidney disease who were followed in the Nephrology Department of Istanbul Goztepe Training and Research Hospital were included in the study. Anthropometric and biochemical measurements for cardiovascular risk factors and metabolic syndrome parameters were recorded. Glomerular filtration rates (GFR) were estimated using the Cockroft Gault formula. Metabolic syndrome was defined according to International Diabetes Federation criteria.

RESULTS

Thirty-seven percent of patients with chronic renal failure were found to have three or more major cardiovascular risk factors. Seventy percent of patients were found to have metabolic syndrome. The mean numbers of major cardiovascular risk factors and metabolic syndrome parameters in patients with different GFR stages were: 1.8 ± 1.0, 2.6 ± 1.2 (GFR <15 mL/min per 1.73 m(2), n = 102); 2.4 ± 1.0, 3.0 ± 1.0 (GFR 15-29 mL/min per 1.73 m(2), n = 51 ); 2.5 ± 1.1, 3.3 ± 1.0 (GFR 30-59 mL/min per 1.73 m(2), n = 39); 2.4 ± 1.1, 3.5 ± 0.7 (GFR 60-89 mL/min per 1.73 m(2), n = 22), respectively (P = .001).

CONCLUSION

Although the frequency of cardiovascular risk factors and metabolic syndrome were high in patients with chronic kidney disease, they were negatively correlated with the stage of renal failure.

Impact of fibroblast growth factor 23 on lipids and atherosclerosis in hemodialysis patients

Levels of fibroblast growth factor (FGF) 23, a phosphatonin, are frequently elevated in patients with end-stage renal disease (ESRD) who are on maintenance hemodialysis (MHD). However, the role of FGF23 remains unclear because renal FGF receptor function might be impaired. The present cross-sectional study examines a cohort of patients (n = 196) on MHD who were not undergoing therapy with lipid-lowering drugs including sevelamer. Non-fasting venous blood samples were withdrawn before the hemodialysis (HD) session on the third day after the previous HD session to measure serum levels of albumin, calcium (Ca), phosphate (P), alkaline phosphatase, intact parathyroid hormone (PTH), total cholesterol (C), high-density lipoprotein (HDL)-C, low-density lipoprotein(LDL)-C, oxidative LDL-C, high-sensitivity C-reactive protein (HsCRP), interleukin-6 (IL-6), and FGF23. Nutritional status was assessed using the geriatric nutritional risk index (GNRI). Carotid intima-medial thickness (CIMT) was assessed using a B-mode ultrasound scanner. FGF23 was positively correlated with P, Ca(alb)xP product, and intact PTH, and inversely correlated with C and non-HDL-C. In the higher FGF23 tertile, levels of both non-HDL-C and C were significantly decreased and CIMT was less elevated compared to the lower FGF23 tertile. Multivariate analysis showed that the higher FGF23 tertile was independently associated with decreases in C (adjusted r(2) = 0.14) and non-HDL-C (adjusted r(2) = 0.20) levels and with a less-pronounced increase in CIMT (adjusted r(2) = 0.14). High FGF23 appears to be an independent biomarker of a decrease in C and non-HDL-C that is negatively associated with atherosclerosis in patients on MHD.

Efficacy and safety of ezetimibe in patients undergoing hemodialysis

Patients with dyslipidemia and advanced renal failure are at markedly increased risk of cardiovascular morbidity and mortality. We evaluated the efficacy and safety of ezetimibe administration to patients with endstage renal failure (ESRF) who are undergoing hemodialysis. Ezetimibe at 10 mg/day was given to 20 patients for 12 weeks. Efficacy was determined by monitoring lipids, and safety was determined by monitoring clinical and laboratory parameters. We also evaluated the effects of ezetimibe on surrogate markers of cholesterol absorption and synthesis. Compared to baseline values, LDL-cholesterol (LDL-C) was reduced by 24.9% (p<0.005) after 12 weeks of ezetimibe administration. Treatment with ezetimibe did not change HDL-cholesterol, triglyceride and HbA1c values but caused a significant reduction in remnant like particles-cholesterol (RLP-C, p<0.05) and high-sensitive C-reactive protein (hsCRP, p<0.05). Ezetimibe therapy decreased cholesterol absorption markers (campesterol and sitosterol) and increased a marker of cholesterol synthesis (lathosterol). A highly significant correlation was observed between alterations in LDL-C and campesterol levels in response to ezetimibe therapy. No patients reported musculoskeletal symptoms. None of the patients experienced elevations in their creatine kinase or liver transaminase levels. Ezetimibe not only reduced serum LDL-C, but also RLP-C and hsCRP, in ESRF patients. Inhibition of cholesterol absorption by ezetimibe is an important therapeutic option in these patients due to its efficacy and safety.

Decreased peroxisome proliferator-activated receptor alpha gene expression is associated with dyslipidemia in a rat model of chronic renal failure

The transcription factor peroxisome proliferator-activated receptor (PPAR) alpha plays an important role in lipid homeostasis. In this study, we examined whether the down-regulation of PPAR-alpha gene expression is associated with dyslipidemia in a rat model of chronic renal failure (CRF). Rats with laboratory-induced uremia by 5/6 nephrectomy were bled at 2 weeks and 10 weeks after the nephrectomy to produce conditions. For the sake of convenience, the rats observed at postoperative week 2 were defined as acute renal failure (ARF) and those observed at week 10 were defined as CRF. Lipids in lipoprotein fractions were measured by high-performance liquid chromatography. The abundance of PPAR-alpha messenger RNA (mRNA) in the liver was measured by reverse transcriptase-polymerase chain reaction. Serum creatinine and blood urea nitrogen levels rose with the progression of renal failure, but the total protein levels remained constant. Serum triglyceride in ARF rats remained unchanged from the level in sham-operated control rats, whereas that in CRF rats was 66% higher than the control level. Serum cholesterol was elevated 1.5-fold in ARF rats and 2-fold in CRF rats compared with the sham-operated counterparts. As with triglyceride, very low-density lipoprotein remained unchanged in ARF rats but rose substantially in CRF rats. All of the major lipoprotein fractions were elevated in CRF rats. These lipid and lipoprotein changes were significantly associated with creatinine and blood urea nitrogen levels. The PPAR-alpha mRNA expression in the liver was unchanged in ARF rats but was 44% lower in CRF rats. The PPAR-alpha mRNA expression was inversely correlated with serum creatinine and lipids in the overall rats. Our results indicate that PPAR-alpha mRNA expression is down-regulated in the liver of CRF rats and that this down-regulation may play a crucial role in the development of dyslipidemia.