Erythrocyte PAF-acetylhydrolase activity in various stages of chronic kidney disease: effect of long-term therapy with erythropoietin

Erythropoiesis-stimulating agents for anaemia in adults with chronic kidney disease: a network meta-analysis

BACKGROUND

Erythropoiesis-stimulating agents (ESAs) are commonly used to treat anaemia in people with chronic kidney disease (CKD). However, their use has been associated with cardiovascular events. This is an update of a Cochrane review first published in 2014.

OBJECTIVES

To compare the efficacy and safety of ESAs (epoetin alfa, epoetin beta, darbepoetin alfa, methoxy polyethylene glycol-epoetin beta, and biosimilar ESAs against each other, placebo, or no treatment) to treat anaemia in adults with CKD.

SEARCH METHODS

In this update, we searched the Cochrane Kidney and Transplant Register of Studies up to 29 April 2022 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that included a comparison of an ESA (epoetin alfa, epoetin beta, darbepoetin alfa, methoxy polyethylene glycol-epoetin beta, a biosimilar epoetin or a biosimilar darbepoetin alfa) with another ESA, placebo or no treatment in adults with CKD were considered for inclusion.

DATA COLLECTION AND ANALYSIS

Two independent authors screened the search results and extracted data. Data synthesis was performed using random-effects pairwise meta-analysis (expressed as odds ratios (OR) and their 95% confidence intervals (CI)) and network meta-analysis. We assessed for heterogeneity and inconsistency within meta-analyses using standard techniques and planned subgroup and meta-regression to explore sources of heterogeneity or inconsistency. We assessed certainty in treatment estimates for the primary outcomes (preventing blood transfusions and death (any cause)) using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Sixty-two new studies (9237 participants) were included in this update, so the review now includes 117 studies with 25,237 participants. Most studies were at high or unclear risk of bias in most methodological domains. Overall, results remain similar in this update compared to our previous review in 2014. For preventing blood transfusion, epoetin alfa (OR 0.28, 95% CI 0.13 to 0.61; low certainty evidence) and epoetin beta (OR 0.19, 95% CI 0.08 to 0.47; low certainty evidence) may be superior to placebo, and darbepoetin alfa was probably superior to placebo (OR 0.27, 95% CI 0.11 to 0.67; moderate certainty evidence). Methoxy polyethylene glycol-epoetin beta (OR 0.33, 95% CI 0.11 to 1.02; very low certainty evidence), a biosimilar epoetin (OR 0.34, 95% CI 0.11 to 1.03; very low certainty evidence) and a biosimilar darbepoetin alfa (OR 0.37, 95% CI 0.07 to 1.91; very low certainty evidence) had uncertain effects on preventing blood transfusion compared to placebo. The comparative effects of ESAs compared with another ESA on preventing blood transfusions were uncertain, in low to very low certainty evidence. Effects on death (any cause) were uncertain for epoetin alfa (OR 0.79, 95% CI 0.51 to 1.22; low certainty evidence), epoetin beta (OR 0.69, 95% CI 0.40 to 1.20; low certainty evidence), methoxy polyethylene glycol-epoetin beta (OR 1.07, 95% CI 0.67 to 1.71; very low certainty evidence), a biosimilar epoetin (OR 0.80, 95% CI 0.47 to 1.36; low certainty evidence) and a biosimilar darbepoetin alfa (OR 1.63, 95% CI 0.51 to 5.23; very low certainty evidence) compared to placebo. There was probably no difference between darbepoetin alfa and placebo on the odds of death (any cause) (OR 0.99, 95% CI 0.81 to 1.21; moderate certainty evidence). The comparative effects of ESAs compared with another ESA on death (any cause) were uncertain in low to very low certainty evidence. Epoetin beta probably increased the odds of hypertension when compared to placebo (OR 2.17, 95% CI 1.17 to 4.00; moderate certainty evidence). Compared to placebo, epoetin alfa (OR 2.10, 95% CI 1.22 to 3.59; very low certainty evidence), darbepoetin alfa (OR 1.88, 95% CI 1.12 to 3.14; low certainty evidence) and methoxy polyethylene glycol-epoetin beta (OR 1.98, 95% CI 1.05 to 3.74; low certainty evidence) may increase the odds of hypertension, but a biosimilar epoetin (OR 1.88, 95% CI 0.96 to 3.67; low certainty evidence) and biosimilar darbepoetin alfa (OR 1.98, 95% CI 0.84 to 4.66; low certainty evidence) had uncertain effects on hypertension. The comparative effects of all ESAs compared with another ESA, placebo or no treatment on cardiovascular death, myocardial infarction, stroke, vascular access thrombosis, kidney failure, and breathlessness were uncertain. Network analysis for fatigue was not possible due to sparse data.  AUTHORS' CONCLUSIONS: The comparative effects of different ESAs on blood transfusions, death (any cause and cardiovascular), major cardiovascular events, myocardial infarction, stroke, vascular access thrombosis, kidney failure, fatigue and breathlessness were uncertain.

Integrative phosphatidylcholine metabolism through phospholipase A2 in rats with chronic kidney disease

Dysregulation in lipid metabolism is the leading cause of chronic kidney disease (CKD) and also the important risk factors for high morbidity and mortality. Although lipid abnormalities were identified in CKD, integral metabolic pathways for specific individual lipid species remain to be clarified. We conducted ultra-high-performance liquid chromatography-high-definition mass spectrometry-based lipidomics and identified plasma lipid species and therapeutic effects of Rheum officinale in CKD rats. Adenine-induced CKD rats were administered Rheum officinale. Urine, blood and kidney tissues were collected for analyses. We showed that exogenous adenine consumption led to declining kidney function in rats. Compared with control rats, a panel of differential plasma lipid species in CKD rats was identified in both positive and negative ion modes. Among the 50 lipid species, phosphatidylcholine (PC), lysophosphatidylcholine (LysoPC) and lysophosphatidic acid (LysoPA) accounted for the largest number of identified metabolites. We revealed that six PCs had integral metabolic pathways, in which PC was hydrolysed into LysoPC, and then converted to LysoPA, which was associated with increased cytosolic phospholipase A2 protein expression in CKD rats. The lower levels of six PCs and their corresponding metabolites could discriminate CKD rats from control rats. Receiver operating characteristic curves showed that each individual lipid species had high values of area under curve, sensitivity and specificity. Administration of Rheum officinale significantly improved impaired kidney function and aberrant PC metabolism in CKD rats. Taken together, this study demonstrates that CKD leads to PC metabolism disorders and that the dysregulation of PC metabolism is involved in CKD pathology.

Evidence of Blood and Muscle Redox Status Imbalance in Experimentally Induced Renal Insufficiency in a Rabbit Model

Chronic kidney disease (CKD) is accompanied by a disturbed redox homeostasis, especially in end-stage patients, which is associated with pathological complications such as anemia, atherosclerosis, and muscle atrophy. However, limited evidence exists about redox disturbances before the end stage of CKD. Moreover, the available redox literature has not yet provided clear associations between circulating and tissue-specific (muscle) oxidative stress levels. The aim of the study was to evaluate commonly used redox status indices in the blood and in two different types of skeletal muscle (psoas, soleus) in the predialysis stages of CKD, using an animal model of renal insufficiency, and to investigate whether blood redox status indices could be reflecting the skeletal muscle redox status. Indices evaluated included reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione reductase (GR), catalase (CAT), total antioxidant capacity (TAC), protein carbonyls (PC), and thiobarbituric acid reactive substances (TBARS). Results showed that blood GSH was higher in the uremic group compared to the control (17.50 ± 1.73 vs. 12.43 ± 1.01, p = 0.033). In both muscle types, PC levels were higher in the uremic group compared to the control (psoas: 1.086 ± 0.294 vs. 0.596 ± 0.372, soleus: 2.52 ± 0.29 vs. 0.929 ± 0.41, p < 0.05). The soleus had higher levels of TBARS, PC, GSH, CAT, and GR and lower TAC compared to the psoas in both groups. No significant correlations in redox status indices between the blood and skeletal muscles were found. However, in the uremic group, significant correlations between the psoas and soleus muscles in PC, GSSG, and CAT levels emerged, not present in the control. Even in the early stages of CKD, a disturbance in redox homeostasis was observed, which seemed to be muscle type-specific, while blood levels of redox indices did not seem to reflect the intramuscular condition. The above results highlight the need for further research in order to identify the key mechanisms driving the onset and progression of oxidative stress and its detrimental effects on CKD patients.

Oxidative Stress and Cardiovascular Complications in Chronic Kidney Disease, the Impact of Anaemia

Patients with chronic kidney disease (CKD) have significant cardiovascular morbidity and mortality as a result of risk factors such as left ventricular hypertrophy (LVH), oxidative stress, and inflammation. The presence of anaemia in CKD further increases the risk of LVH and oxidative stress, thereby magnifying the deleterious consequence in uraemic cardiomyopathy (UCM), and aggravating progression to failure and increasing the risk of sudden cardiac death. This short review highlights the specific cardio-renal oxidative stress in CKD and provides an understanding of the pathophysiology and impact of uraemic toxins, inflammation, and anaemia on oxidative stress.

The CKD plasma lipidome varies with disease severity and outcome

BACKGROUND

Various alterations in lipid metabolism have been observed in patients with chronic kidney disease (CKD).

OBJECTIVES

To determine the levels of lipid species in plasma from CKD and hemodialysis (HD) patients and test their association with CKD severity and patient outcome.

METHODS

Seventy-seven patients with CKD stage 2 to HD were grouped into classes of CKD severity at baseline and followed-up for 3.5 years for the occurrence of transition to HD or death (combined outcome). Plasma levels of phosphatidylcholines (PCs), lysophosphatidylcholines (LPCs), sphingomyelins (SMs), and fatty acids were analyzed by flow-injection analysis coupled to tandem mass spectrometry or gas chromatography coupled with mass spectrometry. Kruskal Wallis rank tests and Cox regressions were used to analyze the association of lipids with CKD severity and the risk of combined outcome, respectively.

RESULTS

The plasma level of PCs, LPCs, and SMs was decreased in HD patients compared with nondialyzed CKD patients (all P < .05), whereas esterified and/or nonesterified fatty acids level did not change. Thirty-four lipids displayed significantly lower abundance in plasma of HD patients, whereas elaidic acid (C18:1ω9t) level was increased (P < .001). The total amount of LPCs and individual LPCs were associated with better outcome (P < .05). In particular, LPC 18:2 and LPC 20:3 were statistically associated with outcome in adjusted models (P < .05).

DISCUSSION

In HD patients, a reduction in plasma lipids is observed. Some of the alterations, namely reduced LPCs, were associated with the risk of adverse outcome. These changes could be related to metabolic dysfunctions.

Systemic Redox Imbalance in Chronic Kidney Disease: A Systematic Review

Patients with chronic kidney disease (CKD) experience imbalance between oxygen reactive species (ROS) production and antioxidant defenses leading to cell and tissue damage. However, it remains unclear at which stage of renal insufficiency the redox imbalance becomes more profound. The aim of this systematic review was to provide an update on recent advances in our understanding of how the redox status changes in the progression of renal disease from predialysis stages 1 to 4 to end stage 5 and whether the various treatments and dialysis modalities influence the redox balance. A systematic review was conducted searching PubMed and Scopus by using the Cochrane and PRISMA guidelines. In total, thirty-nine studies met the inclusion criteria and were reviewed. Even from an early stage, imbalance in redox status is evident and as the kidney function worsens it becomes more profound. Hemodialysis therapy per se seems to negatively influence the redox status by the elevation of lipid peroxidation markers, protein carbonylation, and impairing erythrocyte antioxidant defense. However, other dialysis modalities do not so far appear to confer advantages. Supplementation with antioxidants might assist and should be considered as an early intervention to halt premature atherogenesis development at an early stage of CKD.

Erythropoiesis-stimulating agents for anaemia in adults with chronic kidney disease: a network meta-analysis

BACKGROUND

Several erythropoiesis-stimulating agents (ESAs) are available for treating anaemia in people with chronic kidney disease (CKD). Their relative efficacy (preventing blood transfusions and reducing fatigue and breathlessness) and safety (mortality and cardiovascular events) are unclear due to the limited power of head-to-head studies.

OBJECTIVES

To compare the efficacy and safety of ESAs (epoetin alfa, epoetin beta, darbepoetin alfa, or methoxy polyethylene glycol-epoetin beta, and biosimilar ESAs, against each other, placebo, or no treatment) to treat anaemia in adults with CKD.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 11 February 2014 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that included a comparison of an ESA (epoetin alfa, epoetin beta, darbepoetin alfa, methoxy polyethylene glycol-epoetin beta, or biosimilar ESA) with another ESA, placebo or no treatment in adults with CKD and that reported prespecified patient-relevant outcomes were considered for inclusion.

DATA COLLECTION AND ANALYSIS

Two independent authors screened the search results and extracted data. Data synthesis was performed by random-effects pairwise meta-analysis and network meta-analysis. We assessed for heterogeneity and inconsistency within meta-analyses using standard techniques and planned subgroup and meta-regression to explore for sources of heterogeneity or inconsistency. We assessed our confidence in treatment estimates for the primary outcomes within network meta-analysis (preventing blood transfusions and all-cause mortality) according to adapted GRADE methodology as very low, low, moderate, or high.

MAIN RESULTS

We identified 56 eligible studies involving 15,596 adults with CKD. Risks of bias in the included studies was generally high or unclear for more than half of studies in all of the risk of bias domains we assessed; no study was low risk for allocation concealment, blinding of outcome assessment and attrition from follow-up. In network analyses, there was moderate to low confidence that epoetin alfa (OR 0.18, 95% CI 0.05 to 0.59), epoetin beta (OR 0.09, 95% CI 0.02 to 0.38), darbepoetin alfa (OR 0.17, 95% CI 0.05 to 0.57), and methoxy polyethylene glycol-epoetin beta (OR 0.15, 95% CI 0.03 to 0.70) prevented blood transfusions compared to placebo. In very low quality evidence, biosimilar ESA therapy was possibly no better than placebo for preventing blood transfusions (OR 0.27, 95% CI 0.05 to 1.47) with considerable imprecision in estimated effects. We could not discern whether all ESAs were similar or different in their effects on preventing blood transfusions and our confidence in the comparative effectiveness of different ESAs was generally very low. Similarly, the comparative effects of ESAs compared with another ESA, placebo or no treatment on all-cause mortality were imprecise.All proprietary ESAs increased the odds of hypertension compared to placebo (epoetin alfa OR 2.31, 95% CI 1.27 to 4.23; epoetin beta OR 2.57, 95% CI 1.23 to 5.39; darbepoetin alfa OR 1.83, 95% CI 1.05 to 3.21; methoxy polyethylene glycol-epoetin beta OR 1.96, 95% CI 0.98 to 3.92), while the effect of biosimilar ESAs on developing hypertension was less certain (OR 1.18, 95% CI 0.47 to 2.99). Our confidence in the comparative effects of ESAs on hypertension was low due to considerable imprecision in treatment estimates. The comparative effects of all ESAs on cardiovascular mortality, myocardial infarction (MI), stroke, and vascular access thrombosis were uncertain and network analyses for major cardiovascular events, end-stage kidney disease (ESKD), fatigue and breathlessness were not possible. Effects of ESAs on fatigue were described heterogeneously in the available studies in ways that were not useable for analyses.

AUTHORS' CONCLUSIONS

In the CKD setting, there is currently insufficient evidence to suggest the superiority of any ESA formulation based on available safety and efficacy data. Directly comparative data for the effectiveness of different ESA formulations based on patient-centred outcomes (such as quality of life, fatigue, and functional status) are sparse and poorly reported and current research studies are unable to inform care. All proprietary ESAs (epoetin alfa, epoetin beta, darbepoetin alfa, and methoxy polyethylene glycol-epoetin beta) prevent blood transfusions but information for biosimilar ESAs is less conclusive. Comparative treatment effects of different ESA formulations on other patient-important outcomes such as survival, MI, stroke, breathlessness and fatigue are very uncertain.For consumers, clinicians and funders, considerations such as drug cost and availability and preferences for dosing frequency might be considered as the basis for individualising anaemia care due to lack of data for comparative differences in clinical benefits and harms.

Erythropoiesis-stimulating agents for anaemia in adults with chronic kidney disease: a network meta-analysis

BACKGROUND

Several erythropoiesis-stimulating agents (ESAs) are available for treating anaemia in people with chronic kidney disease (CKD). Their relative efficacy (preventing blood transfusions and reducing fatigue and breathlessness) and safety (mortality and cardiovascular events) are unclear due to the limited power of head-to-head studies.

OBJECTIVES

To compare the efficacy and safety of ESAs (epoetin alfa, epoetin beta, darbepoetin alfa, or methoxy polyethylene glycol-epoetin beta, and biosimilar ESAs, against each other, placebo, or no treatment) to treat anaemia in adults with CKD.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 11 February 2014 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that included a comparison of an ESA (epoetin alfa, epoetin beta, darbepoetin alfa, methoxy polyethylene glycol-epoetin beta, or biosimilar ESA) with another ESA, placebo or no treatment in adults with CKD and that reported prespecified patient-relevant outcomes were considered for inclusion.

DATA COLLECTION AND ANALYSIS

Two independent authors screened the search results and extracted data. Data synthesis was performed by random-effects pairwise meta-analysis and network meta-analysis. We assessed for heterogeneity and inconsistency within meta-analyses using standard techniques and planned subgroup and meta-regression to explore for sources of heterogeneity or inconsistency. We assessed our confidence in treatment estimates for the primary outcomes within network meta-analysis (preventing blood transfusions and all-cause mortality) according to adapted GRADE methodology as very low, low, moderate, or high.

MAIN RESULTS

We identified 56 eligible studies involving 15,596 adults with CKD. Risks of bias in the included studies was generally high or unclear for more than half of studies in all of the risk of bias domains we assessed; no study was low risk for allocation concealment, blinding of outcome assessment and attrition from follow-up. In network analyses, there was moderate to low confidence that epoetin alfa (OR 0.18, 95% CI 0.05 to 0.59), epoetin beta (OR 0.09, 95% CI 0.02 to 0.38), darbepoetin alfa (OR 0.17, 95% CI 0.05 to 0.57), and methoxy polyethylene glycol-epoetin beta (OR 0.15, 95% CI 0.03 to 0.70) prevented blood transfusions compared to placebo. In very low quality evidence, biosimilar ESA therapy was possibly no better than placebo for preventing blood transfusions (OR 0.27, 95% CI 0.05 to 1.47) with considerable imprecision in estimated effects. We could not discern whether all ESAs were similar or different in their effects on preventing blood transfusions and our confidence in the comparative effectiveness of different ESAs was generally very low. Similarly, the comparative effects of ESAs compared with another ESA, placebo or no treatment on all-cause mortality were imprecise.All proprietary ESAs increased the odds of hypertension compared to placebo (epoetin alfa OR 2.31, 95% CI 1.27 to 4.23; epoetin beta OR 2.57, 95% CI 1.23 to 5.39; darbepoetin alfa OR 1.83, 95% CI 1.05 to 3.21; methoxy polyethylene glycol-epoetin beta OR 1.96, 95% CI 0.98 to 3.92), while the effect of biosimilar ESAs on developing hypertension was less certain (OR 1.18, 95% CI 0.47 to 2.99). Our confidence in the comparative effects of ESAs on hypertension was low due to considerable imprecision in treatment estimates. The comparative effects of all ESAs on cardiovascular mortality, myocardial infarction (MI), stroke, and vascular access thrombosis were uncertain and network analyses for major cardiovascular events, end-stage kidney disease (ESKD), fatigue and breathlessness were not possible. Effects of ESAs on fatigue were described heterogeneously in the available studies in ways that were not useable for analyses.

AUTHORS' CONCLUSIONS

In the CKD setting, there is currently insufficient evidence to suggest the superiority of any ESA formulation based on available safety and efficacy data. Directly comparative data for the effectiveness of different ESA formulations based on patient-centred outcomes (such as quality of life, fatigue, and functional status) are sparse and poorly reported and current research studies are unable to inform care. All proprietary ESAs (epoetin alfa, epoetin beta, darbepoetin alfa, and methoxy polyethylene glycol-epoetin beta) prevent blood transfusions but information for biosimilar ESAs is less conclusive. Comparative treatment effects of different ESA formulations on other patient-important outcomes such as survival, MI, stroke, breathlessness and fatigue are very uncertain.For consumers, clinicians and funders, considerations such as drug cost and availability and preferences for dosing frequency might be considered as the basis for individualising anaemia care due to lack of data for comparative differences in clinical benefits and harms.

Rapid resolution liquid chromatography coupled with quadrupole time-of-flight mass spectrometry-based metabolomics approach to study the effects of jieduquyuziyin prescription on systemic lupus erythematosus

Jieduquyuziyin prescription (JP), a traditional Chinese medicine (TCM) prescription, has been widely used for the clinical treatment of systemic lupus erythematosus (SLE). However, the complex chemical constituents of JP and the multifactorial pathogenesis of SLE make research on the therapeutic mechanism of JP in SLE challenging. In this paper, a serum metabolomics approach based on rapid resolution liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (RRLC-Q-TOF/MS) was employed to acquire the metabolic characteristics of serum samples obtained from mice in the SLE model group, JP-treated group, prednisone acetate (PA)-treated group and control group. The orthogonal partial least squares (OPLS) was applied to recognize metabolic patterns, and an obvious separation of groups was obtained. Thirteen metabolites, namely, phosphatidylethanolamine (PE 20:3), hepoxilin B3, lyso- phosphatidylethanolamine (lyso-PE 22:6), 12S-hydroxypentaenoic acid (12S-HEPE), traumatic acid, serotonin, platelet-activating factor (PAF), phosphatidylcholine (PC 20:5),eicosapentaenoic acid (EPA), 12(S)-hydroxyei- cosatetraenoic acid (12S-HETE), 14-hydroxy docosahexaenoic acid (14-HDOHE), lyso-phosphatidylcholine (lyso-PC 20:4), and indole acetaldehyde, were identified and characterized as differential metabolites involved in the pathogenesis of SLE. After treatment with JP, the relative content of 12(S)-HETE, PAF, 12(S)-HEPE, EPA, PE (20:3), Lyso-PE(22:6), and 14-HDOHE were effectively regulated, which suggested that the therapeutic effects of JP on SLE may involve regulating disturbances to the metabolism of unsaturated fatty acid, tryptophan and phospholipid. This research also demonstrated that metabolomics is a powerful tool for researching complex disease mechanisms and evaluating the mechanism of action of TCM.

Paricalcitol effects on activities and metabolism of platelet activating factor and on inflammatory cytokines in hemodialysis patients

PURPOSE

Paricalcitol improves the inflammatory status of hemodialysis patients. PAF is a strong inflammatory mediator which is produced during hemodialysis. We studied the effects of paricalcitol on PAF and other inflammatory mediators implicated in chronic kidney disease (CKD).

METHODS

We examined the in vitro effects of paricalcitol on PAF/thrombin-induced aggregation as well as on the activities of PAF-basic metabolic enzymes, lyso-PAF acetyltransferase (Lyso-PAF-AT), DTT-insensitive CDP-choline: 1-alkyl-2-acetyl-sn-glycerol cholinephospho-transferase (PAF-CPT) and PAF-acetylhydrolase (PAF-AH) in blood cells from healthy volunteers. In addition, the in vivo effects of paricalcitol on the above these enzymes were examined in plasma and blood cells of hemodialysis patients who had not received any type of vitamin D treatment during the last three months before and after receiving paricalcitol for a month. Finally, IL-12p70, IL-1β, IL-6, IL-8 and TNF-α were measured.

RESULTS

Paricalcitol inhibited in vitro PAF/thrombin-induced platelet aggregation and the inhibitory effect was comparable with that of PAF/thrombin antagonists. In addition, paricalcitol inhibited in vitro PAF-CPT activity in platelets and leukocytes and increased PAF-AH activity in leukocytes, while much higher concentrations of paricalcitol were needed to inhibit Lyso-PAF-AT activity. Similarly, in hemodialysis patients, paricalcitol treatment reduced PAF-CPT activity in platelets and leukocytes and increased PAF-AH activity in leukocytes, while it could not influence Lyso-PAF-AT activity. On the other hand, paricalcitol therapy reduced IL-8, IL-1β, and TNF-α.

CONCLUSIONS

These results further support the beneficial effects of vitamin D treatment in hemodialysis patients, since it strongly affects PAF/thrombin activities, PAF-metabolism, and IL-8, IL-1β and TNF-α circulating levels.

Plasma levels of lipoprotein-associated phospholipase A(2) are increased in patients with β-thalassemia

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is an independent cardiovascular risk factor. We investigated the plasma levels of Lp-PLA(2) activity and mass as a function of plasma lipid levels, LDL subclass profile, and oxidative stress in patients with β-thalassemia. Thirty-five patients with β-thalassemia major (β-TM) and 25 patients with β-thalassemia intermedia (β-TI) participated in the study. Lp-PLA(2) activity and mass were measured in total plasma, in apolipoprotein (apo)B-depleted plasma (HDL-Lp-PLA(2)), and in LDL subclasses. Lp-PLA(2) activity produced and secreted from peripheral blood monocytes in culture was also determined. Patients with β-thalassemia are characterized by a predominance of small-dense LDL particles, increased oxidative stress, and very high plasma levels of Lp-PLA(2) mass and activity, despite low LDL-cholesterol levels. A significant positive correlation between plasma Lp-PLA(2) activity or mass and 8-isoprostane (8-epiPGF2a) and ferritin levels as well as intima-media thickness (IMT) values was observed. An increase in secreted and cell-associated Lp-PLA(2) activity from monocytes in culture was observed in both patient groups. The HDL-Lp-PLA(2) activity and mass as well as the ratio of HDL-Lp-PLA(2)/plasma Lp-PLA(2) were significantly higher in both patient groups compared with the control group. In conclusion, patients with β-thalassemia exhibit high plasma Lp-PLA(2) levels, attributed to increased enzyme secretion from monocytes/macrophages and to the predominance of sdLDL particles in plasma. Plasma Lp-PLA(2) is correlated with carotid IMT, suggesting that this enzyme may be implicated in premature carotid atherosclerosis observed in β-thalassemia.

Effects of Darbepoetin Alfa on plasma mediators of oxidative and nitrosative stress in anemic patients with chronic heart failure secondary to ischemic or idiopathic dilated cardiomyopathy

Increased oxidative and nitrosative stress are important mediators of left ventricular (LV) and vascular dysfunction in patients with chronic heart failure (CHF). This study investigated the effects of darbepoetin alfa on plasma markers of oxidative and nitrosative stress in patients with CHF with anemia. Thirty patients with CHF (LV ejection fraction [LVEF] <40%, hemoglobin <12.5 g/dl, and serum creatinine <2.5 mg/dl) were randomly assigned (1:1) to receive either a 3-month darbepoetin alfa regimen at 1.5 microg/kg every 20 days plus oral iron or placebo plus oral iron. Plasma B-type natriuretic peptide (BNP), markers of oxidative (oxidative, malondialdehyde, carbonyl proteins; antioxidative, glutathione) and nitrosative (nitrotyrosine) stress, LVEF, and 6-minute walked distance were assessed at baseline and after treatment. A significant improvement in LVEF and 6-minute walked distance was observed in only darbepoetin-treated patients. Plasma BNP (F = 14.8, p = 001), malondialdehyde (F = 9.4, p = 0.006), protein carbonyl (F = 9.2, p = 0.006), and nitrotyrosine (F = 4.4, p = 0.045) were significantly decreased, along with an increase in antioxidative glutathione (F = 4.2, p = 0.049) after darbepoetin alfa treatment. These factors were unaffected in placebo-treated patients. Darbepoetin-induced percentages of change in carbonyl protein significantly correlated with respective changes in plasma BNP (r = 0.55, p <0.05) and LVEF (r = -0.46, p <0.05). Finally, a drug-induced percentage of decrease in nitrotyrosine significantly correlated with the respective improvement in 6-minute walked distance (r = -0.63, p <0.05). In conclusion, darbepoetin alfa attenuated deleterious effects of oxidative and nitrosative stress into the cardiovascular system of anemic patients with CHF, improving also cardiac function and exercise capacity.

Increase in oxidative stress but not in antioxidant capacity with advancing stages of chronic kidney disease

BACKGROUND/AIMS

Increased oxidative stress in chronic kidney disease (CKD) was suggested to be both a cause and an effect of renal injury. However, the evolution of oxidant stress from early stages of renal function decline is not fully clear. This study aimed to determine the oxidant-antioxidant balance across the whole range of renal function.

METHODS

A total of 116 patients with CKD (85 predialysis patients divided into groups according to CKD stage, and 31 patients with end-stage renal disease (ESRD) on hemodialysis treatment), as well as 29 healthy subjects were evaluated. Plasma levels of 15-F(2t)-isoprostane (15-F(2t)-IsoP), a valid marker of oxidant stress, as well as total antioxidant capacity (TAC) and serum levels of vitamin E were measured in all participants.

RESULTS

Plasma 15-F(2t)-IsoP levels were higher in predialysis and ESRD patients compared to healthy subjects and were progressively increasing with advancing CKD stages (p < 0.001). In contrast, plasma TAC was similar between healthy subjects and predialysis patients, and presented a small reduction in ESRD patients (p < 0.001). Vitamin E levels were higher in healthy subjects compared to any other group (p < 0.001) and slightly higher in ESRD patients compared to predialysis patients (p < 0.01), but did not differ significantly between the groups of predialysis patients. Plasma 15-F(2t)-IsoP levels were inversely correlated with estimated glomerular filtration rate in predialysis patients (r = -0.65, p < 0.001).

CONCLUSIONS

This study shows that 15-F(2t)-IsoP levels increase progressively with advancing CKD stages, whereas TAC and vitamin E levels remain rather stable with the loss of renal function and change only in patients with ESRD.

Administration of exogenous erythropoietin beta affects lipid peroxidation and serum paraoxonase-1 activity and concentration in predialysis patients with chronic renal disease and anaemia

1. Patients with advanced chronic renal disease and anaemia have decreased serum paraoxonase-1 (PON1) activity and an increased degree of oxidative stress compared with normal subjects. The present study investigated the effects of treatment of anaemia with exogenous recombinant erythropoietin (EPO) beta and iron on levels of antibodies against oxidized low-density lipoproteins (ox-LDL), as well as on serum PON1 activity and concentration, in predialysis patients with chronic renal disease. 2. Forty-nine patients with chronic renal failure and haemoglobin (Hb) < 11 g/dL were treated over a period of 6 months with EPObeta (80-120 U/kg per week, s.c.) and variable doses of iron. Selected biochemical variables were determined before and after treatment. 3. Treatment with EPObeta and iron was associated with a significant increase in mean (+/-SD) blood Hb concentration compared with pretreatment values (12.8 +/- 1.5 vs 9.9 +/- 0.6 g/dL, respectively; P < 0.001). The average dose of EPObeta was 6160 +/- 3000 U/week. After 6 months of treatment, compared with pretreatment values, the median levels (95% confidence intervals) of antibodies against ox-LDL were decreased (17.5 (10.6-24.4) vs 24.8 (11.5-38.1) U/mL, respectively; P < 0.001), serum PON1 activity was slightly but significantly increased (123.6 (76.1-343.6) vs 101.0 (50.0-332.5) U/L, respectively; P = 0.016) and the concentration of PON1 was significantly decreased (37.3 (11.8-76.2) vs 46.7 (24.6-98.0) mg/L, respectively; P < 0.001). There were no significant changes in total cholesterol, triglycerides or cholesterol fraction concentrations before and after treatment. 4. We suggest that EPObeta and iron treatment of anaemia promotes significant changes in serum PON1 activity and concentration and has a beneficial effect on oxidative stress in predialysis patients with chronic renal disease.

Oxidative stress is progressively enhanced with advancing stages of CKD

BACKGROUND

Oxidative stress appears to have a central role in the pathophysiological process of uremia and its complications, including cardiovascular disease. However, there is little evidence to suggest how early oxidative stress starts developing during the progression of chronic kidney disease (CKD). The aim of this study is to assess oxidative stress activity in a cross-sectional study of patients with CKD stages 1 to 4.

METHODS

Eighty-seven steady patients (47 men, 40 women) with a median age of 62 years (range, 28 to 84 years) and mean estimated glomerular filtration rate (eGFR) of 57 mL/min (0.95 mL/s) were studied. Levels of plasma 8-isoprostanes (8-epiPGF2a) and serum total antioxidant status (TAS) were used as markers of oxidative stress. 8-epiPGF2a levels were determined by using an enzyme-linked immunosorbent assay method, whereas a chromatometric method was used to determine TAS.

RESULTS

Plasma 8-epiPGF2a levels increased significantly as CKD stages advanced (P < 0.001). There was a highly significant inverse correlation between 8-epiPGF2a level and GFR (P < 0.01). Serum TAS levels also increased in a similar fashion (P < 0.009) and showed a significant inverse correlation with GFR (P < 0.01). 8-epiPGF2a and TAS levels showed a positive correlation (P < 0.05). Multiple regression analysis showed that the most significant predictor variable for 8-epiPGF2a level was eGFR, whereas the association between eGFR and TAS was affected strongly by confounding variables, mainly uric acid level.

CONCLUSION

Oxidative stress appears to increase as CKD progresses and correlates significantly with level of renal function. Increased TAS seems to be dependent on several confounding variables, including increased uric acid levels, and therefore does not seem to be a reliable method for assessing the antioxidant capacity of patients with CKD. These results suggest that larger studies using the correct markers to assess the timing and complex interplay of oxidative stress and other risk factors during the progression of CKD should be carried out.

Erythropoietin and the cardiorenal syndrome: cellular mechanisms on the cardiorenal connectors

We have recently proposed severe cardiorenal syndrome (SCRS), in which cardiac and renal failure mutually amplify progressive failure of both organs. This frequent pathophysiological condition has an extremely poor prognosis. Interactions between inflammation, the renin-angiotensin system, the balance between the nitric oxide and reactive oxygen species and the sympathetic nervous system form the cardiorenal connectors and are cornerstones in the pathophysiology of SCRS. An absolute deficit of erythropoietin (Epo) and decreased sensitivity to Epo in this syndrome both contribute to the development of anemia, which is more pronounced than renal anemia in the absence of heart failure. Besides expression on erythroid progenitor cells, Epo receptors are present in the heart, kidney, and vascular system, in which activation results in antiapoptosis, proliferation, and possibly antioxidation and anti-inflammation. Interestingly, Epo can improve cardiac and renal function. We have therefore reviewed the literature with respect to Epo and the cardiorenal connectors. Indeed, there are indications that Epo can diminish inflammation, reduce renin-angiotensin system activity, and shift the nitric oxide and reactive oxygen species balance toward nitric oxide. Information about Epo and the sympathetic nervous system is scarce. This analysis underscores the relevance of a further understanding of clinical and cellular mechanisms underlying protective effects of Epo, because this will support better treatment of SCRS.

Long-term treatment with EPO increases serum levels of high-density lipoprotein in patients with CKD

BACKGROUND

Among lipid abnormalities observed in patients with chronic kidney disease (CKD) is a significant decrease in serum high-density lipoprotein cholesterol (HDL-C) levels. In a previously published randomized control trial, we showed that early erythropoietin (EPO) administration in a predialysis population slowed the progression of CKD. In the present nested substudy, we examine whether EPO has an influence on serum HDL-C levels in comparison to other lipid parameters in this population.

METHODS

Eighty-eight patients with CKD stages 3 and 4 were enrolled in the study. Forty-five patients (group 1) were treated with EPO (50 U/kg/wk), targeting to increase hemoglobin levels to 13 g/dL or greater (>or=130 g/L). The other patients (group 2) remained without treatment until hemoglobin levels decreased to less than 9 g/dL (<90 g/L). The duration of the study was 12 months.

RESULTS

At the end of the study, we observed a statistically significant decrease in serum levels of total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides in both groups. However, serum HDL-C levels significantly increased in only group 1 (from 42.5 +/- 10.4 to 55.9 +/- 8.1 mg/dL [1.10 +/- 0.27 to 1.45 +/- 0.21 mmol/L]; P < 0.001), whereas they were unchanged in group 2. In addition, a significant decrease in atherogenic LDL-C/HDL-C ratio was observed in only group 1. Importantly, the increase in serum HDL-C levels correlated positively with the increase in hemoglobin values in EPO-treated patients.

CONCLUSION

Our results show that EPO treatment of predialysis patients with CKD significantly increases serum HDL-C levels, which may represent an important antiatherogenic effect of this hormone.

Recombinant human erythropoietin for chronic renal failure anaemia in pre-dialysis patients

BACKGROUND

Treatment with recombinant human erythropoietin (rHu EPO) in dialysis patients has been shown to be highly effective in terms of correcting anaemia and improving quality of life. There is debate concerning the benefits of rHu EPO use in pre-dialysis patients which may accelerate the deterioration of renal function. However the opposing view is that if rHu EPO is as effective in pre-dialysis patient's, improving the patients sense of well-being may result in the onset of dialysis being delayed.

OBJECTIVES

To assess the effects of rHu EPO use in pre-dialysis patients with renal anaemia.

SEARCH STRATEGY

The initial search included 13 electronic databases (1980 to May 2001) an internet search (August 1997), handsearching of Kidney International (1983 to May 1997), contact with known investigators and biomedical companies, and reference list of relevant articles. For this update we searched the Cochrane Renal Group's specialised register (June 2004) and The Cochrane Library (Issue 3, 2004).

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-RCTs comparing the use of rHu EPO with no treatment or placebo in pre-dialysis patients.

DATA COLLECTION AND ANALYSIS

Only published data were used. Quality assessment was performed by two assessors independently. Data were abstracted by a single author onto a standard form, a sample of which was checked by another author. Results were expressed as relative risk (RR) or weighted mean difference (WMD) with 95% confidence intervals (CI).

MAIN RESULTS

Fifteen trials (461 participants) were included. There was a marked improvement in haemoglobin (WMD 1.82 g/dL, 95% CI 1.35 to 2.28) and haematocrit (WMD 9.85%, 95% CI 8.35 to 11.34) with treatment and a decrease in the number of patients requiring blood transfusions (RR 0.32, 95% CI 0.12 to 0.83). The data from studies reporting quality of life or exercise capacity demonstrated an improvement in the treatment group. Most of the measures of progression of renal disease showed no statistically significant difference. No significant increase in adverse events was identified.

AUTHORS' CONCLUSIONS

Treatment with rHu EPO in pre-dialysis patients corrects anaemia, avoids the requirement for blood transfusions and also improves quality of life and exercise capacity. We were unable to assess the effects of rHu EPO on progression of renal disease, delay in the onset of dialysis or adverse events. Based on the current evidence, decisions on the putative benefits in terms of quality of life are worth the extra costs of pre-dialysis rHu EPO need careful evaluation.