Comparison of Fatty Acid Contents of Erythrocyte Membrane in Hemodialysis and Peritoneal Dialysis Patients

The relationship between cognitive impairment and fatty acids and carnitine in hemodialysis patients

BACKGROUND/AIM

The prevalence of cognitive impairment (CI) is high in hemodialysis patients. In this study, the relationship between CI and serum carnitine, plasma omega-3, omega-6 and omega-3/omega-6 fatty acid ratio was evaluated in hemodialysis patients.

MATERIALS AND METHODS

Sixty two patients [male: 40 (64.5%), mean age 51±13 years] were included in this cross-sectional study. Serum total and free-carnitine levels were determined by ELISA. Plasma omega-3 [eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA)] and omega-6 [arachidonic acid (AA), dihomo gamma linoleic acid (DGLA)] levels were measured using LC-ESI-MS/MS. According to the Montreal Cognitive Assessment (MoCA) scores, ≤24 points were considered as CI. MoCA score ≤24 and >24 were determined as Group 1 and Group 2, respectively.

RESULTS

Group 1 had significantly higher AA+DGLA/EPA+DHA ratios and lower free-carnitine, DHA and EPA+DHA levels compared to Group 2 (P=0.008, P=0.040, P=0.032, P=0.032, respectively). Group 1 had a statistically lower education level (P<0.05). Negative correlation was found between MoCA scores and AA+DGLA/EPA+DHA ratios (rs=-0.284, P=0.026). Free-carnitine levels were positively correlated with EPA and EPA+DHA levels (rs=0.278, P=0.030 and rs=0.271, P=0.034, respectively), and negative correlated with AA+DGLA/EPA+DHA ratios (rs=-0.414, P=0.001). In multivariate logistic regression analysis, MoCA scores was associated with AA+DGLA/EPA+DHA ratio (P=0.009) and education level (P<0.001).

CONCLUSION

It was determined that high AA+DGLA/EPA+DHA ratio and low education level could be independent risk factors of the CI. It has been shown that free-carnitine level can have positive effects on plasma EPA+DHA and AA+DGLA distributions. Low omega-3 fatty acid levels may be associated with CI in hemodialysis patients, and low carnitine level may contribute partially to this process. In addition, cognitive education programs may have an effect on preventing CI in hemodialysis patients with low education levels.

Effect of age and dietary habits on Red Blood Cell membrane fatty acids in a Southern Europe population (Basque Country)

The levels of blood eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are very variable and, in general, low in most of the world population. In this study, the effects of age, sex, COVID-19, and dietary habits on the lipid profile of the erythrocyte membranes were assessed in a sub-cohort of healthy population (N = 203) from a large cohort of individuals from the Basque Country, Spain, (AKRIBEA). Sex did not have an effect on RBC lipid profile. COVID-19 infected participants showed higher levels of DGLA. Oldest participants showed higher oleic acid, EPA and DHA levels. Arachidonic acid in RBC correlated positively with the intake of sunflower oil, butter, eggs, processed and red meat, whereas DHA and EPA correlated positively with oily and lean fish. Basque Country population showed lipid profiles similar to other high fish consuming countries, such as Italy and Japan. Baseline levels of the whole lipidomic profile of the RBC including SFA, MUFA and PUFA should be examined to obtain a better description of the health and nutritional status.

LC-MS/MS based metabolomics and proteomics reveal candidate biomarkers and molecular mechanism of early IgA nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN), a globally common primary chronic glomerulopathy, is one of the leading causes of end-stage renal disease. However, the underlying mechanisms of IgAN have yet to be demonstrated. There were no adequate and reliable plasma biomarkers for clinical diagnosis, especially at the early stage. In the present study, integrative proteomics and metabolomics were aimed at exploring the mechanism of IgAN and identifying potential biomarkers.

METHODS

Plasma from IgAN and healthy individuals were collected and analyzed in a randomized controlled manner. Data-independent acquisition quantification proteomics and mass spectrometry based untargeted metabolomics techniques were used to profile the differentially expressed proteins (DEPs) and differentially abundant metabolites (DAMs) between two groups and identify potential biomarkers for IgAN from health at the early stage. Disease-related pathways were screened out by clustering and function enrichment analyses of DEPs and DAMs. And the potential biomarkers for IgAN were identified through the machine learning approach. Additionally, an independent cohort was used to validate the priority candidates by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Proteomic and metabolomic analyses of IgAN plasma showed that the complement and the immune system were activated, while the energy and amino acid metabolism were disordered in the IgAN patients. PRKAR2A, IL6ST, SOS1, and palmitoleic acid have been identified as potential biomarkers. Based on the AUC value for the training and test sets, the classification performance was 0.994 and 0.977, respectively. The AUC of the external validation of the four biomarkers was 0.91.

CONCLUSION

In this study, we combined proteomics and metabolomics techniques to analyze the plasma of IgAN patients and healthy individuals, constructing a biomarker panel, which could provide new insights and provide potential novel molecular diagnoses for IgAN.

Effect of pravastatin on erythrocyte membrane fatty acid contents in patients with chronic kidney disease

Background

Statin treatment has decreased the risk of cardiovascular events in patients with chronic kidney disease (CKD). Erythrocyte membrane oleic acid level is higher in patients with acute coronary syndrome. This study aimed to evaluate the effect of pravastatin on the erythrocyte membrane fatty acid (FA) contents in patients with CKD.

Methods

Sixty-two patients were enrolled from January 2017 to March 2019 (NCT02992548). Pravastatin was initially administered at a dose of 20 mg for 24 weeks. The pravastatin dose was increased to 40 mg after 12 weeks if it was necessary to control dyslipidemia. The primary outcome was change in erythrocyte membrane FA, including oleic acid, after pravastatin treatment for 24 weeks.

Results

Forty-five patients finished this study, and there was no adverse effect related to pravastatin. Compared with baseline, total cholesterol and low-density lipoprotein cholesterol levels were significantly decreased after pravastatin treatment. Compared with baseline, saturated FA, oleic acid, and arachidonic acid levels were significantly increased and polyunsaturated FA and linoleic acid (LA) levels were significantly decreased after pravastatin treatment. There was also a decrease in eicosapentaenoic acid after pravastatin treatment in CKD patients with estimated glomerular filtration rate < 60 mL/min/1.73 m².

Conclusion

Administration of pravastatin in patients with CKD leads to a decrease in FA known to be protective against the risk of CVD. Omega-3 FA or LA supplementation might be necessary to recover changes in erythrocyte membrane FA contents when pravastatin is used for treating dyslipidemia in patients with CKD.

Comparison of Erythrocyte Membrane Lipid Profiles between NAFLD Patients with or without Hyperlipidemia

Nonalcoholic fatty liver disease (NAFLD) and hyperlipidemia (HL) are common metabolic disorders due to overnutrition and obesity. NAFLD is often associated with hyperlipidemia. The aim of this study was to identify and compare the erythrocyte membrane lipids profile in NAFLD patients with or without HL. Methods. A total of 112 subjects (with similar age and body mass index) were divided into four groups: (1) normal controls, (2) NAFLD alone, (3) HL alone, and (4) NAFLD combined with HL (NAFLD + HL). Lipid was extracted from the erythrocyte membrane, and lipid profiles of subjects were analyzed by liquid chromatography mass spectrometry (LC-MS). Results. Data sets from 103 subjects were adopted for lipidomic analysis. Significant changes of lipid species were observed in patient groups, especially in the HL group and NAFLD + HL group. The HL group showed increased level of most lipid species, and decreased level of most lipid species was observed in the NAFLD + HL group. The weight percent of myristic acid, stearic acid, erucic acid, and docosahexaenoic acid also showed distinct variation between different groups. Conclusions. NAFLD, HL, and NAFLD + HL all had an impact on lipid profiling of the erythrocyte membrane. The influence of NAFLD alone is less important compared with HL. Some lipids should be highlighted because of their specific role in cell function and systemic metabolism.

Supplementary nutrients for prevention of vascular calcification in patients with chronic kidney disease

Vascular calcification (VC) and malnutrition associated with cardiovascular disease are common in patients with chronic kidney disease (CKD) treated with dialysis. VC, which reflects vascular aging, and malnutrition are also encountered in the non-CKD elderly population. This similarity of clinical findings suggests that the progression of CKD is related to aging and the existence of a causal relationship between VC and malnutrition. To retard renal progression, a low- or very-low-protein diet is usually recommended for CKD patients. Dietary education may induce malnutrition and deficiency of important nutrients, such as vitamins K and D. Menaquinone-7, a type of vitamin K2, is under investigation for inhibiting VC in elderly patients without CKD, as well as for prevention of VC in patients with CKD. Nutritional vitamin D, such as cholecalciferol, may be considered to decrease the required dose of active vitamin D, which increases the risk of VC due to increased calcium and phosphate loads. Omega-3 fatty acids are important nutrients and their ability to inhibit VC needs to be evaluated in clinical trials. This review focuses on the ability of supplementary nutrients to prevent VC in patients with CKD, in whom dietary restriction is essential.

Effect of Omega-3 Fatty Acid on STAMP2 Expression in the Heart and Kidney of 5/6 Nephrectomy Rat Model

Six transmembrane protein of prostate 2 (STAMP2) is a critical modulator of inflammation and metabolism in adipose tissue. There are no data on the expression of STAMP2 in chronic kidney disease, which is an inflammatory disease related to metabolic disorders. This study aimed to investigate STAMP2 expression in the kidney and heart in 5/6 nephrectomy (Nx) rats, and the effect of omega-3 fatty acid (FA) on STAMP2 expression. Male Sprague Dawley rats were divided into three groups: sham control (0.9% saline), 5/6 Nx (0.9% saline), and 5/6 Nx treated with omega-3 FA (300 mg per kg per day by gastric gavage). The expression of STAMP2 in the kidney and heart were examined by western blotting. Serum creatinine levels were higher in 5/6 Nx rats than in controls. Compared with sham controls, the expression of IκB, NF-κB, NOX4, SREBP-1, and LXR were upregulated and STAMP2 and phosphorylated-AMPK expression were downregulated in the kidney and heart of 5/6 Nx rats. Omega-3 FA supplementation prevented these changes in biomarkers related to inflammation and metabolic lipid disorders. Omega 3-FA supplementation induced the upregulation of STAMP2 protein in 5/6 Nx rats, which was associated with an attenuation of inflammation- and metabolic disease-related markers.

Impact of Blood or Erythrocyte Membrane Fatty Acids for Disease Risk Prediction: Focusing on Cardiovascular Disease and Chronic Kidney Disease

Fatty acids (FAs) are essential nutrients and main constituents of cell membranes that are involved in the signaling pathway and associated with health conditions. We investigated if blood or erythrocyte membrane FAs can predict the risk of cardiovascular disease (CVD), chronic kidney disease (CKD), and related complications. Omega-3 (n-3) FAs are important predictors for metabolic syndrome, diabetes, CVD, and CKD risks, and the n-3 index is also a good biomarker for sudden cardiac death in coronary artery disease. Linoleic acid, which is one of the major n-6 FAs reflecting recent dietary FA intake, may predict CVD risk and mortality in the general population and patients with CKD. Monounsaturated FAs (MUFAs) are also related to diabetes or diabetic nephropathy. Oleic acid, a major MUFA, is an emerging marker that is related to acute coronary syndrome, low glomerular filtration rate, and vascular calcification in patients with CKD, and can be modified by n-3 FA supplementation. Saturated FAs, trans-FAs, and FA desaturation/elongation are associated with CVD risk; however, few studies have been conducted on patients with CKD. In summary, blood or erythrocyte membrane FA measurements are important for CVD and CKD risk prediction and management. Further studies are needed to elucidate the FAs for their risk predictions.

Blood Fatty Acid Status and Clinical Outcomes in Dialysis Patients: A Systematic Review

Blood fatty acids (FAs) are derived from endogenous and dietary routes. Metabolic abnormalities from kidney dysfunction, as well as cross-cultural dietary habits, may alter the FA profile of dialysis patients (DP), leading to detrimental clinical outcomes. Therefore, we aimed to (i) summarize FA status of DP from different countries, (ii) compare blood FA composition between healthy controls and DP, and (iii) evaluate FA profile and clinical endpoints in DP. Fifty-three articles from 1980 onwards, reporting FA profile in hemodialysis and peritoneal DP, were identified from PubMed, Embase, and the Cochrane library. Studies on pediatric, predialysis chronic kidney disease, acute kidney injury, and transplant patients were excluded. Moderate to high levels of n-3 polyunsaturated fatty acids (PUFA) were reported in Japan, Korea, Denmark, and Sweden. Compared to healthy adults, DP had lower proportions of n-3 and n-6 PUFA, but higher proportion of monounsaturated fatty acids. Two studies reported inverse associations between n-3 PUFAs and risks of sudden cardiac death, while one reported eicosapentaenoic acid + docosahexaenoic acid)/arachidonic acid ratio was inversely associated with cardiovascular events. The relationship between all-cause mortality and blood FA composition in DP remained inconclusive. The current evidence highlights a critical role for essential FA in nutritional management of DP.

Altered Serum n-6 Polyunsaturated Fatty Acid Profile and Risks of Mortality and Cardiovascular Events in a Cohort of Hemodialysis Patients

OBJECTIVE

Alterations in the balance between serum n-3 and n-6 polyunsaturated fatty acids (PUFAs) is predictive of cardiovascular events among hemodialysis patients, although little is known about the serum ratio of n-6 arachidonic acid (AA) to n-6 dihomo-γ-linoleic acid (DGLA) in renal failure. We hypothesized that AA/DGLA ratio is altered in hemodialysis patients resulting in poor clinical outcomes.

METHODS

This was a single center cohort study in an urban area in Japan with cross-sectional analyses. Subjects were 517 hemodialysis patients and 122 control subjects. The main exposure was serum AA/DGLA ratio, and the main outcome measures were all-cause mortality and cardiovascular events during 5 years.

RESULTS

The hemodialysis patients showed a higher median (interquartile range) AA/DGLA ratio than the control subjects (6.46 [5.22-7.81] versus 4.56 [3.74-6.34], P < .001). In a Cox proportional hazard model adjusted for age, sex, dialysis duration, diabetic nephropathy, prior cardiovascular disease, and the ratio of serum n-3 polyunsaturated fatty acids (eicosapentaenoic acid plus docosahexaenoic acid) to AA, the higher quartiles of AA/DGLA ratio were associated with higher risk for all-cause mortality with hazard ratios (95% confidence interval) of 1.50 (0.84-2.76) for quartile 2, 2.10 (1.18-3.86) for quartile 3, and 2.02 (1.10-3.78) for quartile 4 compared with quartile 1. AA/DGLA ratio showed a similar association with the risk of cardiovascular events.

CONCLUSIONS

AA/DGLA ratio was elevated in patients with end-stage renal disease requiring hemodialysis, and a high AA/DGLA ratio was an independent predictor of poor clinical outcomes in this population.

Diet quality in patients with end-stage kidney disease undergoing dialysis

BACKGROUND

People on haemodialysis (HD) are at risk of consuming a poor quality diet. This includes inadequate intake of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA).

OBJECTIVE

This study aims to investigate diet quality, with a particular focus on n-3 LCPUFA intake, in a population of incentre HD patients.

DESIGN

Dietary intake was measured using three 24 hour recalls; the Polyunsaturated food frequency questionnaire (PUFA FFQ) and the Total Diet Score (TDS). Dietary intake was also compared to evidence based practice guidelines (EBPG). Nutritional status was assessed using the Patient Generated Subjective Global Assessment (PG SGA).

SUBJECTS

A total of 32 dialysis patients were recruited, from two regional HD centres in New South Wales, Australia.

MAIN OUTCOME MEASURE

Diet quality was the main outcome measure.

RESULTS

Diet quality of study participants was poor, with the majority not meeting the EBPG for energy, protein and potassium. All participants exceeded the recommended amount of saturated fat. The mean TDS of the dialysis cohort was 10.2, which was significantly higher than the TDS of 9.3 of a healthy disease free cohort (p < 0.05). Positive correlations were found between TDS and LC omega-3 intake (r = 0.392) and TDS and total omega-6 intake (r = 0.363). Only 22% of participants met the suggested dietary target for n-3 LCPUFA intake.

CONCLUSION

Dialysis patients in this study had suboptimal diet quality. Improvements are required for better adherence to the EBPG. Increased consumption of n-3 LCPUFA fatty acids may also be of benefit.

Suitability of selected chromatographic columns for analysis of fatty acids in dialyzed patients

Gas chromatography-mass spectrometry is a preferred method for fatty acid (FA) analysis in biofluids from patients with metabolic diseases. Complex characteristics of FAs make their analysis particularly challenging. Selection of an appropriate chromatographic column is particularly important component of the process as it provides optimal separation and detection of possibly all FAs present in the sample. However, no accurate protocol for comparative evaluation of capillary columns for the analysis of whole serum FA profile in patients with chronic kidney disease (CKD) has been developed thus far. Therefore, in the present study four columns were examined to select the one providing optimal separation and determination of FA profiles in this group of patients. Moreover, serum FA profiles obtained with the selected column in CKD patients subjected to peritoneal dialysis and healthy controls were compared. Thirty-seven component FAME Mix and sera from CKD patients were used to optimize chromatographic conditions and to select the most appropriate column. The ZB-5 column turned out to be the most appropriate for the analysis of whole FA profile in CKD patients' sera. Then, this column was used to compare FA profiles in patients subjected to peritoneal dialysis and in healthy controls. The analysis demonstrated many abnormalities in the FA profile of CKD patients. Further studies involving larger groups of patients presenting with other stages of CKD are required to explain the impact of the disease progression on composition of serum FAs.

Long chain n-3 polyunsaturated fatty acids and vascular function in patients with chronic kidney disease and healthy subjects: a cross-sectional and comparative study

Background

Patients with chronic kidney disease have a markedly increased cardiovascular mortality compared with the general population. Long chain n-3 polyunsaturated fatty acids have been suggested to possess cardioprotective properties. This cross-sectional and comparative study evaluated correlations between hemodynamic measurements, resistance artery function and fish consumption to the content of long chain n-3 polyunsaturated fatty acids in adipose tissue, a long-term marker of seafood intake.

Methods

Seventeen patients with chronic kidney disease stage 5 + 5d and 27 healthy kidney donors were evaluated with hemodynamic measurements before surgery; from these subjects, 11 patients and 11 healthy subjects had vasodilator properties of subcutaneous resistance arteries examined. The measurements were correlated to adipose tissue n-3 polyunsaturated fatty acids. Information on fish intake was obtained from a dietary questionnaire and compared with adipose tissue n-3 polyunsaturated fatty acids.

Results

Fish intake and the content of n-3 polyunsaturated fatty acids in adipose tissue did not differ between patients and controls. n-3 polyunsaturated fatty acid levels in adipose tissue were positively correlated to systemic vascular resistance index; (r = 0.44; p = 0.07 and r = 0.62; p < 0.05, chronic kidney disease and healthy subjects respectively) and negatively correlated to cardiac output index (r = −0.69; p < 0.01 and r = −0.50; p < 0.05, chronic kidney disease and healthy subjects respectively). No correlation was observed between n-3 polyunsaturated fatty acid levels in adipose tissue and vasodilator properties in resistance arteries. n-3 PUFA content in adipose tissue increased with increasing self-reported fish intake.

Conclusions

The correlations found, suggest a role for n-3 polyunsaturated fatty acids in hemodynamic properties. However, this is apparently not due to changes in intrinsic properties of the resistance arteries as no correlation was found to n-3 polyunsaturated fatty acids.

Global survey of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid in the blood stream of healthy adults

Studies reporting blood levels of the omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were systematically identified in order to create a global map identifying countries and regions with different blood levels. Included studies were those of healthy adults, published in 1980 or later. A total of 298 studies met all inclusion criteria. Studies reported fatty acids in various blood fractions including plasma total lipids (33%), plasma phospholipid (32%), erythrocytes (32%) and whole blood (3.0%). Fatty acid data from each blood fraction were converted to relative weight percentages (wt.%) and then assigned to one of four discrete ranges (high, moderate, low, very low) corresponding to wt.% EPA+DHA in erythrocyte equivalents. Regions with high EPA+DHA blood levels (>8%) included the Sea of Japan, Scandinavia, and areas with indigenous populations or populations not fully adapted to Westernized food habits. Very low blood levels (≤4%) were observed in North America, Central and South America, Europe, the Middle East, Southeast Asia, and Africa. The present review reveals considerable variability in blood levels of EPA+DHA and the very low to low range of blood EPA+DHA for most of the world may increase global risk for chronic disease.

Plasma and erythrocyte membrane phospholipids and fatty acids in Italian general population and hemodialysis patients

Background

Dyslipidemia and abnormal phospholipid metabolism are frequent in uremic patients and increase their risk of cardiovascular disease (CVD): ω-3 polyunsaturated fatty acids (PUFAs) may reduce this risk in the general population. In this study we compared the plasma and erythrocyte cell membrane composition of PUFAs in a group of Caucasian hemodialysis (HD) patients and in a control group of healthy subjects and evaluated the erythrocyte/cell membrane fatty acid ratio as a marker of the dietary intake of phospholipids. The relationship between ω-3 and ω-6 fatty acids and the possible differences in PUFAs concentrations were also investigated.

Methods and results

After obtaining a fully informed consent, a total of ninety-nine HD patients and 160 non uremic control subjects from “Tor Vergata” University Hospital were enrolled into the study. None of them took antioxidant drugs or dietary supplements for at least 90 days prior to the observation. Blood samples were analysed by gas-chromatographic coupled to a mass spectrometric detector.

The daily intake of total calories, proteins, lipids and carbohydrates is significantly lower in HD patients than in controls (p < 0.001). Most plasma and erythrocyte PUFA were also reduced significantly in HD patients (p < 0.001).

Conclusions

Our results suggest that many classes of PUFAs are lacking in HD patients, due to the removal of nutrients during the dialysis and to persistent malnutrition. A dietary treatment addressed to increase plasma ω-3 PUFAs and to optimize ω-6/ω-3 ratio may exert a protective action and reduce the risk of CVD in HD patient.

Omega-3 index and cardiovascular health

Recent large trials with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the cardiovascular field did not demonstrate a beneficial effect in terms of reductions of clinical endpoints like total mortality, sudden cardiac arrest or other major adverse cardiac events. Pertinent guidelines do not uniformly recommend EPA + DHA for cardiac patients. In contrast, in epidemiologic findings, higher blood levels of EPA + DHA were consistently associated with a lower risk for the endpoints mentioned. Because of low biological and analytical variability, a standardized analytical procedure, a large database and for other reasons, blood levels of EPA + DHA are frequently assessed in erythrocytes, using the HS-Omega-3 Index® methodology. A low Omega-3 Index fulfills the current criteria for a novel cardiovascular risk factor. Neutral results of intervention trials can be explained by issues of bioavailability and trial design that surfaced after the trials were initiated. In the future, incorporating the Omega-3 Index into trial designs by recruiting participants with a low Omega-3 Index and treating them within a pre-specified target range (e.g., 8%-11%), will make more efficient trials possible and provide clearer answers to the questions asked than previously possible.

Comparison of plasma and erythrocyte membrane fatty acid compositions in patients with end-stage renal disease and type 2 diabetes mellitus

BACKGROUND

In this study, we aimed to compare the serum lipid profile and fatty acid (FA) compositions of erythrocyte membrane (EM) and plasma in three different patient groups (group 1: type 2 diabetes mellitus (T2DM)+end-stage renal disease (ESRD), group 2: ESRD, group 4: T2DM) and healthy controls (group 3) simultaneously.

METHODS

40 ESRD patients treated with hemodialysis (HD) in Gulhane School of Medicine (20 with T2DM) and 32 controls (17 with T2DM, 15 healthy controls) were included in the study. Plasma and EM FA concentrations were measured by gas chromatography-flame ionization detector (GC-FID).

RESULTS

Plasma and EM palmitic acid (PA) and stearic acid (SA) levels were significantly higher in T2DM patients compared to controls (p=0.040 and p=0.002 for plasma, p=0.001 and p=0.010 for EM, respectively). EM docosahexaenoic acid (DHA) levels were also significantly lower in patients with ESRD+T2DM and ESRD compared to controls (p=0.004 and p=0.037, respectively).

CONCLUSIONS

Patients with insulin resistance display a pattern of high long chain saturated FAs (PA, SA and arachidic acids). However, while there are no recognized standards for normal EM DHA content, decreased levels of EM DHA in ESRD patient groups (groups 1 and 2) suggest that there may be reduced endogenous synthesis of DHA in HD subjects, due to the decreased functionality of desaturase and elongase enzymes. Because membrane PUFA content affects membrane fluidity and cell signaling, these findings are worthy of further investigation.

Cardioprotective effects of ω -3 PUFAs in chronic kidney disease

The prevalence rate of chronic kidney disease (CKD) is increasing worldwide, and cardiovascular disease (CVD) is a main cause of death in patients with CKD. The high incidence of CVD in CKD patients is related to chronic inflammation, dyslipidemia, malnutrition, atherosclerosis, and vascular calcification. Omega-3 polyunsaturated fatty acids ( ω -3 PUFAs) have been shown to reduce the risk of CVD. In this paper, we review the beneficial effects of ω -3 PUFAs on CVD and the possible cardioprotective mechanisms of ω -3 PUFAs in CKD patients by determining the effect of ω -3 PUFAs in the general population. ω -3 PUFAs have several cardioprotective benefits, such as reducing inflammation, decreasing oxidative stress, inhibiting platelet activity, exerting antiarrhythmic effects, and improving triglyceride levels, in the general population and patients with CKD. Modifications of erythrocyte membrane fatty acid content, including an increased ω -3 index and decreased oleic acid, after ω -3 PUFAs supplementation are important changes related to CVD risk reduction in the general population and patients with CKD. Further basic and clinical studies are essential to confirm the effects of ω -3 PUFAs on vitamin D activation, vascular calcification prevention, cardiovascular events, and mortality in CKD patients.

Clinical determinants and mortality predictability of stearoyl-CoA desaturase-1 activity indices in dialysis patients

BACKGROUND

Stearoyl-CoA desaturase-1 (SCD-1) converts dietary saturated fatty acids to monounsaturated fatty acids. Elevated SCD-1 activity thus signifies impaired fatty acid metabolism and excess saturated fat intake. In the general population, increased SCD-1 activity is associated with cardiovascular disease and mortality. The determinants and implications of SCD-1 activity in dialysis patients are unknown.

SUBJECTS

A total of 222 dialysis patients (39% women) with prospective follow-up, median age of 57 years and an average of 12 months of dialysis.

DESIGN

Fatty acid compositions in plasma phospholipids and free fatty acids (FFAs) were assessed by gas-liquid chromatography. SCD-1 activity indices were calculated as the product-to-precursor fatty acid ratio (palmitoleic acid/palmitic acid) in each fraction to reflect SCD-1 activities in the liver and adipose tissue.

RESULTS

Median hepatic and adipose tissue SCD-1 activity indices were 0.016 and 0.150, respectively. In multivariate analyses, SCD-1 was positively associated with age, female sex and serum interleukin-6 level. During 18.4 (interquartile range 5.5-37.3) months of follow-up, there were 61 deaths and 115 kidney transplants. The cut-off level for high SCD-1 indices was determined by receiver operating characteristic curve analyses. In fully adjusted competing risk models, patients with high SCD-1 indices in both phospholipids and FFAs had more than twofold increased mortality risk before kidney transplantation [hazard ratio (HR) 2.29, 95% confidence interval (CI) 1.28-4.11 and HR 2.36, 95% CI 1.38-4.03, respectively], compared with patients with low SCD-1 indices.

CONCLUSIONS

Both hepatic and adipose tissue SCD-1 activity indices independently predict mortality in dialysis patients. Further studies are warranted to determine whether reducing SCD-1 activity by dietary intervention (limiting saturated fat) could improve survival in dialysis patients.

Comparison of erythrocyte membrane fatty acid contents in renal transplant recipients and dialysis patients

BACKGROUND

Alterations of erythrocyte membrane fatty acid (FA) composition play important roles in cellular function because they change the membrane microenvironment, including transmembrane receptors. The erythrocyte membrane oleic acid content is higher among patients with acute coronary syndrome and also in dialysis patients. However, available data are limited concerning erythrocyte membrane FA content in kidney transplant recipients (KTP). We sought to test the hypothesis that erythrocyte membrane FA content among KTP were different from those in dialysis patients.

METHODS

In this cross-sectional study, we recruited 35 hemodialysis, 33 peritoneal dialysis 49 KTP, and 33 normal control subjects (CTL). Their erythrocyte membrane FA content were measured by gas chromatography.

RESULTS

The mean ages of the enrolled dialysis patients, KTP, and CTL were 56.4 ± 10.1, 48.9 ± 10.4, and 49.5 ± 8.3 years, respectively. Mean kidney transplant duration was 89.8 ± 64.8 months and mean dialysis duration, 49.0 ± 32.6 months. The intakes of vegetable lipid and vegetable protein including total calories were significantly increased among KTP versus dialysis patients. Total cholesterol (P < .001) and high density lipoprotein cholesterol (HDL; P < .001) levels were significantly higher and C-reactive protein was significantly lower among KTP compared with dialysis patients. The erythrocyte membrane content of palmitoleic acid (P < .001) was significantly higher but oleic acid (P < .001) significantly lower in KTP compared with dialysis patients. The erythrocyte membrane contents of arachidonic acid and docosahexaenoic acid were significantly higher, and linoleic acid and the omega-6 FA to omega-3 FA ratio (P < .001) significantly lower in KTP compared with dialysis patients. The erythrocyte membrane content of oleic acid was independently associated with monounsaturated fatty acid (beta = 0.771, P < .001), eicosapentaeonic acid (beta = -0.244, P = .010), and HDL (beta = -0.139, P = .049) in KTP.

CONCLUSIONS

FA contents of erythrocyte membranes were significantly different in KTP compared with dialysis patients. These differences may have been associated with improved dietary intake and immunosuppression after kidney transplantation.

Essential polyunsaturated fatty acids, inflammation and mortality in dialysis patients

BACKGROUND

Polyunsaturated fatty acids (PUFA) are essential nutrients with anti-inflammatory and cardioprotective properties. We investigated the association of essential dietary PUFA intake, reflected by plasma fatty acid composition, with inflammation and mortality in dialysis patients.

METHODS

We recruited 222 Swedish dialysis subjects (39% women) with median age of 57 years and average 12 months of dialysis vintage. Plasma phospholipid PUFA were assessed by gas-liquid chromatography. Overall mortality was assessed after 18.4 (10th-90th percentiles: 2.3-60) months of follow-up.

RESULTS

Linoleic acid (LA), Mead acid (MA), α-linolenic acid (ALA) and long-chain n-3 PUFA (LC n-3; the sum of eicosapentaenoic, docosapentaenoic and docosahexaenoic acids) represented 19.7, 0.26, 0.26 and 7.64% of all fatty acids in plasma, respectively. This may reflect an adequate n-3 PUFA intake. LA was negatively (β = - 0.21, P = 0.004) but MA positively (β = 0.25, P < 0.001) associated with interleukin (IL)-6 in multivariate analyses. Neither ALA nor LC n-3 were independently associated with IL-6. During follow-up, 61 deaths and 115 kidney transplants occurred. Fully adjusted competing risk models showed that every percent increase in the proportion of plasma LA was associated with 12% reduction in mortality risk before transplantation (hazard ratio 0.88, 95% confidence interval 0.79-0.99). MA was directly associated with mortality. Neither ALA nor LC n-3 predicted outcome.

CONCLUSIONS

The proportion of plasma phospholipid LA is inversely associated with IL-6 and all-cause mortality in Swedish dialysis patients. We raise the hypothesis that dialysis patients could benefit from increased intake of vegetable oils, the primary source of LA in the Western-type diet.

Effect of omega-3 fatty acids on the modification of erythrocyte membrane fatty acid content including oleic acid in peritoneal dialysis patients

Erythrocyte membrane fatty acids (FA), such as oleic acid, are related to acute coronary syndrome. There is no report about the effect of omega-3 FA on oleic acid in peritoneal dialysis (PD) patients. We hypothesized that omega-3 FA can modify erythrocyte membrane FA, including oleic acid, in PD patients. In a double-blind, randomized, placebo-controlled study, 18 patients who were treated with PD for at least 6 months were randomized to treatment for 12 weeks with omega-3 FA or placebo. Erythrocyte membrane FA content was measured by gas chromatography at baseline and after 12 weeks. The erythrocyte membrane content of eicosapentaenoic acid and docosahexaenoic acid was significantly increased and saturated FA and oleic acid were significantly decreased in the omega-3 FA supplementation group after 12 weeks compared to baseline. In conclusion, erythrocyte membrane FA content, including oleic acid, was significantly modified by omega-3 FA supplementation for 12 weeks in PD patients.

Association between vascular calcification scores on plain radiographs and fatty acid contents of erythrocyte membrane in hemodialysis patients

OBJECTIVE

Vascular calcification (VC) scores determined by using simple plain radiographic films are known to be associated with coronary artery disease and mortality in patients undergoing hemodialysis (HD). Omega-3 fatty acid (FA) has been shown to reduce ectopic calcifications in an animal model, and it has also been shown that erythrocyte membrane omega-3 FA content is an independent discriminator of coronary artery disease. The present study was designed to demonstrate relations between VC scores and erythrocyte membrane FA contents in patients undergoing HD.

DESIGN

A cross-sectional study was carried out.

SETTING

The study was carried out at an outpatient hemodialysis unit at Dong-A University Hospital, Busan, Republic of Korea.

PATIENTS

A total of 31 patients undergoing HD were recruited. Patients with significant malnutrition, a short duration of dialysis (<12 months), a history of recent infection, malignancy, or liver disease were excluded.

MAIN OUTCOME MEASURES

Plain radiographic films of the feet, hands, pelvis, and lateral lumbar spine were examined and VC scores were determined using previously reported methods. Erythrocyte membrane FA contents were analyzed by gas chromatography.

RESULTS

The erythrocyte membrane contents of eicosapentaenoic acid and docosahexaenoic acid were not found to be related with VC on simple plain radiographic films. However, erythrocyte membrane contents of oleic acid and total monounsaturated FA (MUFA) were significantly higher in patients with significant VC scores. Furthermore, erythrocyte membrane contents of MUFA and oleic acid were found to be negatively associated with high-density lipoprotein cholesterol level and positively associated with triglyceride level.

CONCLUSION

Erythrocyte membrane contents of MUFA and oleic acid were found to be associated with VC scores determined using plain radiographs and with dyslipidemia in patients undergoing HD.