Lipoprotein Metabolism and Lipid Management in Chronic Kidney Disease

Dyslipidemia in children with CKD: should we treat with statins?

Dyslipidemia has been shown to be a risk factor for increased cardiovascular morbidity and mortality in adult patients with chronic kidney disease (CKD) stages 2-4. In patients on dialysis, a paradoxical correlation has been found between low cholesterol values and increased mortality rates. No data exist in children. Treatment with statins has been convincingly shown to both reduce blood lipid levels and mortality rates from cardiovascular disease in adult patients in CKD stages 2-4. There is no strong literature support for treating patients on dialysis or after having had a transplant. Data on benefits of statin therapy do not exist in children with CKD. There are many differences between adult and paediatric kidney patients, and I caution on extrapolating the findings in adult patients to children. Studies are thus needed to evaluate the benefits and potential problems of statin treatment in children with CKD.

Statins in the management of dyslipidemia associated with chronic kidney disease

The cause of death in the majority of patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) is accelerated cardiovascular disease and not renal failure per se, suggesting a role for statin therapy in this setting. During the past 6 years three large, randomized, placebo-controlled studies of three different statins have been conducted in the dialysis population-but two of these studies did not demonstrate any benefits of statin therapy, and the third study showed only marginally positive results. To understand why statins have failed to reduce cardiovascular events in patients with ESRD, the basic mechanisms underlying the pathogenesis of dyslipidemia in CKD must be critically examined. The observed negative results in the clinical trials of statin therapy might also reflect the biomarkers and targets that were chosen to be evaluated. The characteristics of dyslipidemia in patients with CKD not yet requiring dialysis treatment differ markedly from those of individuals with established ESRD and form the basis for therapeutic recommendations. The potential adverse effects associated with statin therapy are important to consider in the management of dyslipidemia in patients with CKD.

Serum amyloid A in uremic HDL promotes inflammation

Uremia impairs the atheroprotective properties of HDL, but the mechanisms underlying why this occurs are unknown. Here, we observed that HDL isolated from healthy individuals inhibited the production of inflammatory cytokines by peripheral monocytes stimulated with a Toll-like receptor 2 agonist. In contrast, HDL isolated from the majority of patients with ESRD did not show this anti-inflammatory property; many HDL samples even promoted the production of inflammatory cytokines. To investigate this difference, we used shotgun proteomics to identify 49 HDL-associated proteins in a uremia-specific pattern. Proteins enriched in HDL from patients with ESRD (ESRD-HDL) included surfactant protein B (SP-B), apolipoprotein C-II, serum amyloid A (SAA), and α-1-microglobulin/bikunin precursor. In addition, we detected some ESRD-enriched proteins in earlier stages of CKD. We did not detect a difference in oxidation status between HDL isolated from uremic and healthy patients. Regarding function of these uremia-specific proteins, only SAA mimicked ESRD-HDL by promoting inflammatory cytokine production. Furthermore, SAA levels in ESRD-HDL inversely correlated with its anti-inflammatory potency. In conclusion, HDL has anti-inflammatory activities that are defective in uremic patients as a result of specific changes in its molecular composition. These data suggest a potential link between the high levels of inflammation and cardiovascular mortality in uremia.

Hemodialysis alters lipid profiles, total antioxidant capacity, and vitamins A, E, and C concentrations in humans

Although hemodialysis (HD) is essential for end-stage renal disease patients, at the same time it causes oxidative stress and long-term pro-atherosclerotic effects. This study aimed to determine lipid profile as well as the total antioxidant capacity (TAC) and vitamins A, E, and C in HD patients. The study enrolled 31 patients (50.3 ± 14.9 years old) undergoing maintenance 4-hour HD three times per week with a polysulfone membrane dialyzer for a mean of 76.1 months (range, 7-120 months) and 31 healthy individuals (47.8 ± 13.9 years old). Lipid profiles were determined spectrophotometrically using commercially available kits. Total antioxidant capacity was determined by ferric reducing/antioxidant power assay, levels of vitamins A and E were assayed using high-pressure liquid chromatography, and the level of vitamin C was measured by a photometric method. Our results showed that before HD, the levels of TAC and vitamin A were significantly higher than in normal subjects, whereas the levels of high-density lipoprotein (HDL) and vitamin C were lower than in control subjects (P < .001). There was no significant difference between normal subjects and patients before dialysis regarding low-density lipoprotein (LDL) and vitamin E levels (P > .05). After HD, the levels of HDL-cholesterol, vitamins E and C, and TAC decreased significantly (P < .001), but the decreased level of vitamin A still remained higher than controls (P < .05), whereas the levels of LDL were significantly higher than controls (P < .001). In conclusion, alterations in the lipoprotein profiles and antioxidant markers following HD suggest an increased risk of atherosclerosis in these patients.

The association of mid-regional pro-adrenomedullin and mid-regional pro-atrial natriuretic peptide with mortality in an incident dialysis cohort

High levels of the plasma peptides mid-regional pro-adrenomedullin (MR-proADM) and mid-regional pro-atrial natriuretic peptide (MR-proANP) are associated with clinical outcomes in the general population. Data in patients with chronic kidney disease are sparse. We therefore investigated the association of MR-proANP and MR-proADM levels with all-cause and cardiovascular (CV) mortality, CV events and peripheral arterial disease in 201 incident dialysis patients of the INVOR-Study prospectively followed for a period of up to more than 7 years. The overall mortality rate was 43%, thereof 43% due to CV events. Both baseline MR-proANP and MR-proADM were associated with higher risk of all-cause (HR = 1.44, p = 0.001 and HR = 1.32, p = 0.002, respectively) and CV mortality (HR = 1.75, p<0.001 and HR = 1.41, p = 0.007, respectively) after adjustment for age, sex, previous CV events, diabetes mellitus and time-dependent type of renal replacement therapy. We then stratified patients in high risk (both peptides in the upper tertile), intermediate risk (only one of the two peptides in the upper tertile) and low risk (none in the upper tertile). Although demographic, clinical and laboratory variables were similar among the intermediate and high risk group, to be with both parameters in the upper tertile was associated with a 3-fold higher risk for all-cause (HR = 2.87, p<0.001) and CV mortality (HR = 3.58, p = 0.001). In summary, among incident dialysis patients MR-proANP and MR-proADM were shown to be associated with all-cause and CV mortality, with the highest risk when both parameters were in the upper tertiles.

Unfractionated heparin for hemodialysis: still the best option

Unfractionated heparin (UFH) is the anticoagulant of choice for most maintenance hemodialysis units in the United States. Low molecular weight heparin (LMWH) is the norm in Western Europe, but is not approved for this indication in the United States. UFH is likely to remain the agent of choice in the United States because of its relative ease of use, safety, and low cost. Coating tubing and dialyzers with heparin is now possible, but systemic anticoagulation with heparin is usually still required. The additional cost of this innovation does not yet justify its use. Side effects of both UFH and LMWH include heparin-induced thrombocytopenia, hypertriglyceridemia, and hyperkalemia. It is uncertain whether osteoporosis is an important side effect, as vitamin D deficiency, secondary hyperparathyroidism, age, and debility are confounding factors. When UFH poses a risk or its use is contraindicated, e.g., after development of heparin-induced thrombocytopenia, the use of direct thrombin inhibitors, regional citrate anticoagulation, citrate dialysate, and heparin-free dialysis may be appropriate.

Role of statins in preventing adverse cardiovascular outcomes in patients with chronic kidney disease

PURPOSE OF REVIEW

Cardiovascular disease accounts for the majority of deaths in chronic kidney disease (CKD). Dyslipidemia is a well established cardiovascular risk factor. We summarize key aspects of available evidence relating to beneficial effects of statins in nondialysis-dependent CKD, dialysis-dependent CKD and renal transplant recipients.

RECENT FINDINGS

Previous trials and their meta-analyses suggested that statins reduce lipid levels, the risk of cardiovascular disease and all-cause mortality in nondialysis-dependent CKD. The Study of Heart and Renal Protection (SHARP) study that enrolled both dialysis-dependent and nondialysis-dependent CKD patients showed a 17% decrease in major atherosclerotic events with statins or ezetimibe. Similar cardiovascular benefits are observed in renal transplant recipients. However, such positive effects were not found in two recent clinical trials that enrolled hemodialysis patients alone. This lack of benefit might be attributed to differences in the cause of cardiovascular death seen in dialysis patients and smaller sample size. The overall benefits-harms tradeoff may benefit from meta-analysis and individual patient data meta-analysis in hemodialysis patients including the SHARP data.

SUMMARY

Nondialysis-dependent CKD patients and renal transplant recipients benefit from statins. Statins have also been found to be beneficial in one of the three large trials in hemodialysis patients, a matter which may be further explored.

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.

Glucose concentration in the dialysate does not contribute to lipid profiles in patients undergoing CAPD

The aim of this study was to investigate lipid profiles in patients with end-stage renal disease receiving hemodialysis (HD), continuous ambulatory peritoneal dialysis (CAPD), or no dialysis (nondialytic treatment group, NT), and to analyze the association between dyslipidemia in CAPD patients with glucose-containing dialysate dosages. Lipid profiles were determined in 64 NT patients, 62 HD patients, and 180 CAPD patients at a single time point. NT patients' samples were collected following hospitalization due to renal failure. HD and CAPD patients' samples were collected after 3 months of dialysis. The association between lipid profiles of 180 CAPD patients and glucose-containing dialysate was analyzed using Pearson methods; 76.56% of NT patients, 66.13% of HD patients, and 72.22% of CAPD patients had dyslipidemia. Compared with NT patients, CAPD patients had significantly altered levels of cholesterol, triglycerides, high-density lipoprotein, apolipoproein (Apo)-A1, and Apo-E (p < 0.05), but unchanged levels of low-density lipoprotein or Apo-B. There was no correlation between the three different concentrations of glucose in the dialysate with the lipid profile of CAPD patients. We concluded that patients on CAPD exhibit dyslipidemia, and that different concentrations of glucose in the dialysate do not affect lipid profiles in these patients.

Cardiorenal syndrome type 4-cardiovascular disease in patients with chronic kidney disease: epidemiology, pathogenesis, and management

The term cardiorenal syndrome refers to the interaction between the heart and the kidney in disease and encompasses five distinct types according to the initial site affected and the acute or chronic nature of the injury. Type 4, or chronic renocardiac syndrome, involves the features of chronic renal disease (CKD) leading to cardiovascular injury. There is sufficient epidemiologic evidence linking CKD with increased cardiovascular morbidity and mortality. The underlying pathophysiology goes beyond the highly prevalent traditional cardiovascular risk burden affecting renal patients. It involves CKD-related factors, which lead to cardiac and vascular pathology, mainly left ventricular hypertrophy, myocardial fibrosis, and vascular calcification. Risk management should consider both traditional and CKD-related factors, while therapeutic interventions, apart from appearing underutilized, still await further confirmation from large trials.

Pharmacotherapy of end-stage renal disease

IMPORTANCE OF THE FIELD

The incidence and prevalence of end-stage renal disease (ESRD) requiring renal replacement therapy (RRT) continues to grow worldwide. ESRD causes significant morbidity and mortality and has enormous financial and personal costs.

AREAS COVERED IN THIS REVIEW

Major electronic databases (including the Cochrane Library, MEDLINE and EMBASE) were searched from 1989 to September 2009 to summarize current pharmacotherapy of ESRD-associated complications in adults receiving maintenance dialysis (hemodialysis or continuous ambulatory peritoneal dialysis). Current guidelines for the treatment of ESRD (e.g., NKF-K/DOQI, KDIGO, and the ERA-EDTA's European Renal Best Practice Guidelines) were included.

WHAT THE READER WILL GAIN

Commonly used pharmacological treatment strategies for chronic arterial hypertension, anemia, iron management, dyslipidemia, hyperglycemia, and for disturbances of bone and mineral metabolism, including hyperphosphatemia and secondary hyperparathyroidism in ESRD, are presented. In addition, the reader will learn that nonadherence to oral medication in ESRD can contribute significantly to excess morbidity and mortality of the dialysis population.

TAKE HOME MESSAGE

Improvements in pharmacotherapy of ESRD may be at least in part counteracted by continuously increasing age and comorbid disease of the dialysis population. Individualized and tailor-made pharmacological management of the ESRD patient remains a challenge for the future.

Biochemistry and biomarkers of inflamed patients: why look, what to assess

Specific laboratory tests and physical findings are available to the practicing clinician that should raise the suspicion of inflammation. Inflammation is related to specific clinical outcomes. Once identified, changes in clinical practice may affect the level of inflammation in individual and or groups of dialysis patients with the hope that these changes may in turn affect outcome in a positive manner. Standard clinical tests and observations associated with inflammation are hypoalbuminemia, erythropoietin resistance, decreased iron saturation accompanied by high ferritin, frailty, low serum creatinine, reduced total and LDL-cholesterol, and increased C reactive protein (CRP). Inflammation is strongly associated with loss of physical function, dyslipidemia (low LDL- and HDL-cholesterol, increased triglycerides), and anemia that is unresponsive to erythropoietin. Inflammation is associated with cardiovascular events, increased hospitalization, and death. Correctible causes of inflammation are tunneled dialysis catheters, arteriovenous grafts, catheter infection, periodontal disease, poor water quality, and dialyzer incompatibility. Obesity also is a source of cytokines but may be less amenable to treatment. Inflammation is multifactorial in dialysis patients. Some sources are recognizable and correctable, such as vascular access type, clinical infection, and water quality, and some are not. Inflammation is strongly associated with outcome.

Hypercholesterolaemia induces early renal lesions characterized by upregulation of MMP-9 and iNOS and ETAR: alleviated by a dual endothelin receptor antagonist CPU0213 and simvastatin

Objectives

We aimed to investigate hypercholesterolaemia-induced early renal lesions which result in abnormal expression of endothelin A receptor (ETAR), induced nitric oxide synthase (iNOS) and matrix metalloproteinase 9 (MMP-9). We hypothesized that this is due to an upregulated endothelin (ET) pathway consequent to hypercholesterolaemia and that CPU0213, a dual ET antagonist, could mitigate these changes.

Methods

Rats were randomly divided into four groups: (1), control; (2), high-fat diet for 60 days (HFD); HFD rats medicated in the last 15 days with either (3) CPU0213 (30 mg/kg daily, s.c.) or (4) simvastatin (4 mg/kg daily, p.o.).

Key findings

Body weight, serum triglycerides, total cholesterol and low-density-lipoprotein cholesterol were significantly increased, whereas high-density lipoprotein cholesterol decreased in the HFD group, relative to normal. Meanwhile, these changes were associated with upregulation of mRNA and protein of ETAR, iNOS and MMP-9 in the kidney. The lipid-lowering effect of simvastatin was predominant, lessening abnormal expression of these molecules in the kidney dramatically. Interestingly, CPU0213 significantly normalized expression of mRNA and protein of ETAR, iNOS and MMP-9, comparable with simvastatin, leaving no changes in hyperlipidaemia.

Conclusions

CPU0213 relieves renal lesions by blunting hypercholesterolaemia caused by the upregulated ET system, iNOS and MMP-9 in the kidney. This indicates that CPU0213 is promising in treating patients with end stage renal disease.

Dyslipidemia of kidney disease

PURPOSE OF REVIEW

Chronic kidney disease is associated with specific alterations of lipoprotein metabolism that may be linked to accelerated atherosclerosis and cardiovascular disease. This review summarizes current knowledge of the pathophysiology of renal dyslipidemia and the therapeutic options.

RECENT FINDINGS

The renal dyslipidemia is characterized by accumulation of intact and partially metabolized triglyceride-rich apoB-containing and apoC-containing lipoproteins. Increased concentrations of atherogenic apoC-III rich lipoproteins, the hallmark of renal dyslipidemia, may result from disturbances of insulin metabolism and action in chronic kidney disease. Novel findings strongly suggest that apoC-III triggers a cascade of pro-inflammatory events, which ultimately can result in endothelial dysfunction and vascular damage. Disappointingly, recently reported intervention trials with statins have failed to show any benefit on cardiovascular disease in patients with advanced renal failure.

SUMMARY

During recent years, our understanding of the character and biological significance of the dyslipidemia of chronic kidney disease, and its link to cardiovascular disease, has increased. However, our knowledge about its proper management is still very limited.

Cardiovascular risk and management in chronic kidney disease

Chronic kidney disease (CKD) is associated with accelerated progression of cardiovascular disease, perhaps because patients with CKD have a high burden of traditional cardiovascular risk factors in addition to a range of nontraditional risk factors such as inflammation and abnormal metabolism of calcium and phosphate. Although the cardiovascular burden of CKD is well documented, potentially beneficial therapies are sometimes underused in patients with stage 3-4 CKD and are rarely studied in patients on dialysis. In this Review, we describe the epidemiology of cardiovascular disease in patients with stage 3-5 CKD (excluding kidney transplant recipients) and outline cardiovascular risk factors that are relevant in this population; we then discuss the implications of this knowledge for the optimal management of cardiovascular risk in this setting. Finally, we highlight opportunities for further research.

Amelioration of renal ischemia-reperfusion injury by inhibition of IL-6 production in the poloxamer 407-induced mouse model of hyperlipidemia

It is largely unknown whether hyperlipidemia is involved in the pathobiology of renal ischemia-reperfusion (I/R) injury that is an important cause of acute kidney injury. Here we studied the effect of experimental dyslipidemia on renal I/R injury. Renal I/R injury was less severe in hyperlipidemic mice treated with poloxamer 407 than in the control mice. Cytokine analyses revealed decreased levels of renal and serum IL-6 in the hyperlipidemic mice after renal I/R. Protection from renal I/R injury in the hyperlipidemic mice was diminished by administration of recombinant IL-6. Concanavalin A-induced IL-6 release from cultured splenocytes derived from the hyperlipidemic mice was lower than that from splenocytes of normal mice. In hypercholesterolemic apolipoprotein E-knockout mice, in which renal I/R injury is less severe than in control mice, renal I/R-induced IL-6 production was also less than that in controls. In angiopoietin-like 3-deficient mice, which were hypolipidemic, renal dysfunction and renal IL-6 level after I/R were similar to those of control mice. Our data indicate that the presence of experimental hyperlipidemia may be associated with a decreased risk of renal I/R injury, possibly mediated by reduced renal IL-6 production after the insult and extend the notion that an anti-IL6 agent would be useful for the treatment of acute kidney injury.