Dietary antioxidents and oxidative stress in predialysis chronic kidney disease patients

Association between oxidative balance score in adults with and without chronic kidney disease: 2011-2028 NHANES

Introduction

Oxidative stress status is associated with CKD; however, few studies have investigated this association. The oxidative balance score (OBS) reflects systemic stress status and consists of 16 anti-and pro-oxidant dietary factors and four anti-and pro-oxidant lifestyle factors. Higher OBS implies exposure to more antioxidants. The purpose of this study was to explore the association between OBS and CKD.

Methods

We enrolled 8,134 study participants from the 2011-2018 National Health and Nutrition Examination Survey and obtained OBS by adding the 20 dietary and lifestyle factors. Based on OBS, the participants were divided into three groups. We performed logistic regression, subgroup analyzes, and restricted cubic spline regression to explore the association between OBS and CKD. In addition, we tested the adjusted model.

Results

OBS was negatively associated with CKD (OR: 0.54; 0.66, 0.82). After adjusting for all confounders, when dietary OBS was >20, the prevalence of CKD was reduced by 42% for each unit increase in OBS (p < 0.05). The negative associations of total OBS, dietary OBS, and lifestyle OBS with CKD were more significant in the female group. When the total OBS was ~20, the trend of decreasing prevalence in the female group was more significant.

Conclusion

OBS is negatively associated with chronic kidney disease.

Dietary intakes of total polyphenol and its subclasses in association with the incidence of chronic kidney diseases: a prospective population-based cohort study

Background

As chronic kidney disease (CKD) is amongst the current global health challenges, this study is aiming to evaluate the long-term intake of total polyphenol and its subclasses in association with CKD incidence.

Methods

For the purpose of this study, a sample of 3021 Iranian adults (47 % men, aged 20–79 years) with no CKD diagnosis at baseline, were selected from the Tehran Lipid and Glucose Study population. The total intake of polyphenol and its major subclasses were assessed by a validated food frequency questionnaire and categorized as flavonoids, phenolic acids, stilbenes, and lignans. Although the morphological abnormalities of the kidneys or 3-month persistent urinalysis can distinctively define CKD, the glomerular filtration rate (eGFR) reduction is accepted as a more precise index of renal function. Therefore, eGFR < 60 mL/min/1.73m² was the exclusive index of CKD diagnosis in the current study. The eGFR was calculated by the Modification of Diet in Renal Disease Study equation. Cox-regression analysis was used to assess the hazard ratio and 95 % confidence intervals of CKD in quartiles of the total polyphenols.

Results

In this study, 355 CKD cases over 11,058.464 person-years was reported. The median (IQR) age of participants was 36 years (27–46) at baseline. Moderate intake of lignans (≤ 6.8 mg) was negatively associated with the incidence of CKD in the adjusted model. No significant associations were detected between higher amounts of lignin and total polyphenols (HR: 0.97, 95 % CI 0.67–1.40) and CKD incidence.

Conclusions

Based on the current findings, moderate intake of lignin possess CKD-protective properties by approximately 32 %. No independent associations were observed between higher amounts of lignins and CKD incidence.

Herbal antioxidants in dialysis patients: a review of potential mechanisms and medical implications

The consumption of exogenous antioxidants isolated from herbal extracts has shown beneficial effects on ameliorating dialysis-related complications through debilitating oxidative stress and inflammatory process. Many clinical studies available in public databases have reported the improved consequences of dialysis in patients supplemented with herbal antioxidants. Exploration of such data offers great possibilities for gaining insights into the potential mechanisms and medical implications of herbal antioxidants. In this work, the mechanisms and implications of some famous bioactive substances including silymarin, curcumin, resveratrol, emodin, and quercetin on the consequences of dialysis in chronic kidney disease (CKD) patients were explored. The protective features of silymarin are due to the flavonoid complex silybin. Curcumin is an active element from the root of curcuma longa with extensive beneficial properties, including antioxidant, anti-inflammatory activity, and inhibitory effects on cell apoptosis. Resveratrol can reduce the oxidative stress by neutralization of free radicals. Emodin is known as a natural anthraquinone derivative isolated from Chinese herbs. Finally, quercetin has been reported to exhibit several properties including antioxidant, anti-diabetic, analgesic, antihistaminic, antiviral, cholesterol reducer, and renal hemodynamic modulator. However, potential mechanisms and medical implications of the aforementioned herbal antioxidants seem to be more complicated, that is, more studies are required in this field.

Follistatin Protects Against Glomerular Mesangial Cell Apoptosis and Oxidative Stress to Ameliorate Chronic Kidney Disease

Aims: Interventions to inhibit oxidative stress and apoptosis, important pathogenic contributors toward the progression of chronic kidney disease (CKD), are not well established. Here, we investigated the role of a transforming growth factor beta (TGFβ) superfamily neutralizing protein, follistatin (FST), in the regulation of apoptosis and oxidative stress in glomerular mesangial cells (MCs) and in the progression of CKD. Results: The endoplasmic reticulum (ER) stress inducer thapsigargin (Tg), known to cause MC apoptosis, led to a post-translational increase in the expression of FST. Recombinant FST protected, whereas FST downregulation augmented, Tg-induced apoptosis without affecting Ca²⁺ release or ER stress induction. Although activins are the primary ligands neutralized by FST, their inhibition with neutralizing antibodies did not affect Tg-induced apoptosis. Instead, FST protected against Tg-induced apoptosis through neutralization of reactive oxygen species (ROS) independently of its ability to neutralize activins. Importantly, administration of FST to mice with CKD protected against renal cell apoptosis and oxidative stress. This was associated with improved kidney function, reduced albuminuria, and attenuation of fibrosis. Innovation and Conclusion: Independent of its activin neutralizing ability, FST protected against Tg-induced apoptosis through neutralization of ROS and consequent suppression of oxidative stress, seen both in vitro and in vivo. Importantly, FST also ameliorated fibrosis and improved kidney function in CKD. FST is, thus, a novel potential therapeutic agent for delaying the progression of CKD. Antioxid. Redox Signal. 31, 551-571.

Dietary Oxidative Balance Scores and Biomarkers of Inflammation among Individuals with and without Chronic Kidney Disease

BACKGROUND

Oxidative stress and inflammation are proposed mechanisms of nonspecific kidney injury and progressive kidney failure. Higher dietary oxidative balance scores (OBS) are associated with lower prevalence of chronic kidney disease (CKD).

METHODS

We investigated the association between OBS and biomarkers of inflammation using data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. Nutrient estimates from the Block Food Frequency Questionnaires were used to define tertiles of 11 pro- and antioxidant factors. Points for each OBS component were summed, with a higher score indicating predominance of antioxidant exposures. Multivariable linear regression models were used to estimate the association between OBS and biomarkers of inflammation (interleukin-6 [IL-6], interleukin-8 [IL-8], interleukin-10 [IL-10], fibrinogen, C-reactive protein [CRP], white blood cell count, and cystatin C). An interaction term was included to determine if associations between OBS and inflammatory markers differed between individuals with and without CKD.

RESULTS

Of 682 participants, 22.4% had CKD. In adjusted models, OBS was associated with CRP and IL-6. For every 5-unit increase in OBS, the CRP concentration was -15.3% lower (95% CI: -25.6, -3.6). The association of OBS with IL-6 differed by CKD status; for every 5-unit increase in OBS, IL-6 was -10.7% lower (95% CI: -16.3, -4.7) among those without CKD, but there was no association among those with CKD (p = 0.03).

CONCLUSION

This study suggests that a higher OBS is associated with more favorable levels of IL-6 and CRP, and that the association of OBS and IL-6 may be modified by CKD status.

Effect of serum albumin on the prognosis of elderly patients with stage 3-4 chronic kidney disease

OBJECTIVE

To investigate the influence of serum albumin on the prognosis of elderly patients with stage 3-4 chronic kidney disease (CKD).

METHODS

From July 2013 to November 2015, elderly CKD patients (≥60 years), with eGFR ≥15 mL/min/1.73 m² and <60 mL/min/1.73 m², with CKD stage 3-4 in the geriatric nephrology clinic were enrolled. General information and underlying diseases were recorded. Laboratory indices were evaluated. Composite endpoint events (CEE) including renal endpoint events, cardiocerebral vascular endpoint events, and death were elucidated. Based on the ROC curves, the patients were divided into lower and higher serum albumin groups (<42.5 and ≥42.5 g/L).

RESULTS

The occurrence of CEEs was significantly higher in lower serum albumin group than those in the higher group. Also, the patients in the higher group were significantly younger with lower urinary protein, blood urea, brain natriuretic peptide, and cystatin C than those in the lower serum albumin group. Contrastingly, hemoglobin, total serum protein, serum calcium, and superoxide dismutase were remarkably higher. The composite endpoints of multifactor logistic regression analysis indicated that as the serum albumin is increased by every 1 g/L, the probability of CEEs would reduce 14.8%, and the risk occurrence rate of the lower serum albumin group was 4.739 fold than the higher group.

CONCLUSION

The results suggest that patients with higher serum albumin had a better prognosis than those with lower serum albumin. The low level was an independent risk factor influencing the prognosis of elderly patients in stage 3-4 CKD.

Vitamin E-coated dialysis membranes reduce the levels of oxidative genetic damage in hemodialysis patients

End-stage renal disease patients present oxidative stress status that increases when they are submitted to hemodialysis (HD). This increase in oxidative stress can affect their genetic material, among other targets. The objective of this study was to evaluate the effect of using polysulfone membranes coated with vitamin E, during the HD sessions, on the levels of genetic damage of HD patients. Forty-six patients were followed for 6 months, of whom 29 changed from conventional HD to the use of membranes coated with vitamin E. The level of genetic damage was measured using the micronucleus and the comet assays, both before and after the follow-up period. Serum vitamin E concentration was also checked. The obtained results showed that 24% of our patients presented vitamin E deficiency, and this was normalized in those patients treated with vitamin E-coated membranes. Patients with vitamin E deficiency showed higher levels of oxidative DNA damage. After the use of vitamin E-coated membranes we detected a significant decrease in the levels of oxidative damage. Additionally, hemoglobin values increased significantly with the use of vitamin E-coated membranes. In conclusion, the use of vitamin E-coated membranes supposes a decrease on the levels of oxidative DNA damage, and improves the uremic anemia status. Furthermore, the use of this type of membrane was also effective in correcting vitamin E deficiency.

Dietary Modeling of Foods for Advanced CKD Based on General Healthy Eating Guidelines: What Should Be on the Plate?

Chronic kidney disease (CKD) is a major public health problem with significant clinical, societal, and psychosocial burdens. Nutrition therapy has been an integral part of the medical management of patients with CKD for more than a century, with the main goals of preserving kidney function and preventing complications. Nutrition abnormalities may emerge well before dialysis therapy is initiated and are associated with poor outcomes. It is therefore important to revisit nutrition management in the advanced stages of CKD to gain a broader insight into its role and effect on patient outcomes. Traditionally, nutrition recommendations have focused on the prescription of energy (calories) and macro- and micronutrients. Today, dietary modeling also focuses on the evidence for food consumption on health. This review argues that advanced non-dialysis-dependent CKD nutrition requirements to a large extent align with healthy eating guidelines for the general population and should not be based on deprivation or be unusually restrictive. The best currently available evidence for the CKD diet is likely to be derived from CKD nutrition prescriptions in conjunction with evidence underpinning national dietary guidelines and evidence of healthy dietary patterns, such as Mediterranean-style and Dietary Approaches to Stop Hypertension (DASH)-style eating. Positive messages from these dietary patterns should improve acceptance of CKD dietary interventions among patients.

Oxidative Balance Score and Chronic Kidney Disease

BACKGROUND

The oxidative balance score (OBS) is a composite estimate of the overall pro- and antioxidant exposure status in an individual. The aim of this study was to determine the association between OBS and renal disease.

METHODS

Using the Reasons for Geographic and Racial Differences in Stroke cohort study, OBS was calculated by combining 13 a priori-defined pro- and antioxidant factors by using baseline dietary and lifestyle assessment. OBS was divided into quartiles (Q1-Q4) with the lowest quartile, Q1 (predominance of pro-oxidants), as the reference. Multivariable logistic regression and Cox proportional hazards models were used to estimate adjusted ORs for albuminuria defined as urine albumin/creatinine ratio (ACR)>30 mg/g, macroalbuminuria defined as ACR>300 mg/g and chronic kidney disease (CKD) defined as estimated glomerular filtration rate<60 ml/min/1.73 m2 according to the Chronic Kidney Disease Epidemiology Collaboration and hazards ratios for end-stage renal disease (ESRD), respectively.

RESULTS

Of the 19,461 participants analyzed, 12.9% had albuminuria and 10.1% had CKD at baseline; over a median follow-up of 3.5 years (range 2.14-4.32 years), 0.46% developed ESRD. Higher OBS quartiles were associated with lower prevalence of CKD (OR vs. Q1: Q2=0.93 [95% CI 0.80-1.08]; Q3=0.90 [95% CI 0.77-1.04] and Q4=0.79 [95% CI 0.67-0.92], p for trend<.01). The associations between OBS and albuminuria (p for trend 0.31) and incident ESRD (p for trend 0.56) were not significant in the fully adjusted models.

CONCLUSIONS

These findings suggest that higher OBS is associated with lower prevalence of CKD. Lack of association with ESRD incidence in the multivariable analyses indicates that temporal relation between OBS and renal damage remains unclear.

Effect of omega-3 supplementation on inflammatory parameters in patients on chronic ambulatory peritoneal dialysis

Background:

End stage renal disease (ESRD) is a state of micro inflammation that attenuates patient's life span and quality of life. Inflammatory markers like interlukin 6 (IL-6) and C- reactive protein (CRP) can predict inflammatory state in ESRD patients. Dietary limitations are risk factors for omega-3 deficiency in these patients. Omega-3 supplementation is an attractive material that proposed in inflammation modulation. The aim of this study is evaluation of effect of omega-3 supplementation on IL-6 and CRP level in chronic ambulatory peritoneal dialysis (CAPD) patients.

Materials and Methods:

This randomized controlled double-blind clinical trial is performed in 40 CAPD patients in two academic hospitals in Isfahan, Iran. One group received 1000 mg omega-3 capsule (each capsule contains 180 mg Eicosapentanoic and 120 mg Dosahexanoic acid) three times a day orally for 8 weeks (n = 20) and the other matched group by placebo (n = 20). Serum level of IL-6 and quantitative CRP (Q-CRP) were measured in beginning and the end of the study. Finally all data were analyzed by SPSS version 18.

Results:

Mean age of patients was 53 years old in omega-3 group patients and 54 years old in placebo group. There were not any differences in CRP and IL-6 level in the beginning and the end of study between two groups (P: 0.81 and 0.10 for CRP and 0.26 and 0.23 for IL-6, respectively).

Conclusion:

Omega-3 supplementation did not effect on inflammatory markers (Q-CRP and IL-6) in CAPD patients after 8 weeks.

Chronic kidney disease influences multiple systems: describing the relationship between oxidative stress, inflammation, kidney damage, and concomitant disease

Chronic kidney disease (CKD) is characterized by increased levels of oxidative stress and inflammation. Oxidative stress and inflammation promote renal injury via damage to molecular components of the kidney. Unfortunately, relationships between inflammation and oxidative stress are cyclical in that the inflammatory processes that exist to repair radical-mediated damage may be a source of additional free radicals, resulting in further damage to renal tissue. Oxidative stress and inflammation also have the ability to become systemic, serving to injure tissues distal to the site of original insult. This review describes select mediators in the exacerbatory relationship between oxidative stress, inflammation, and CKD. This review also discusses oxidative stress, inflammation, and CKD as they pertain to the development and progression of common CKD-associated comorbidities. Lastly, the utility of several widely accessible and cost-effective lifestyle interventions and their ability to reduce oxidative stress and inflammation are discussed and recommendations for future research are provided.

Suppressive impact of anethum graveolens consumption on biochemical risk factors of atherosclerosis in hypercholesterolemic rabbits

BACKGROUND

We aimed to determine the effects of Anethum graveolens (Dill) powder on postprandial lipid profile, markers of oxidation and endothelial activation when added to a fatty meal.

METHODS

In an experimental study, 32 rabbits were randomly designated into four diet groups: normal diet, high cholesterol diet (1%), high cholesterol diet plus 5% (w/w) dill powder and high cholesterol diet plus lovastatin (10 mg/kg, bw). The concentrations of glucose, total cholesterol (TC), low-density lipoproteins-cholesterol (LDL-C), alanine aminotransferase (alt), aspartate aminotransferase (ast), fibrinogen, factor VII, apolipoprotein B (ApoB), nitrite and nitrate were measured in blood samples following 15 h of fasting and 3 h after feeding.

RESULTS

Concurrent use of A. graveolens powder or lovastatin significantly decreased ALT, TC, glucose, fibrinogen and LDL-C values in comparison with hypercholesterolemic diet group (P < 0.05). Consumption of A. graveolens or lovastatin did not change factor VII, ApoB, nitrite and nitrate levels significantly in comparison with hypercholesterolemic diet group. Intake of A. graveolens significantly decreased serum AST compared to hypercholesterolemic diet.

CONCLUSIONS

A. graveolens might have some protective values against atherosclerosis and that it significantly affects some biochemical risk factors of this disease. Our findings also confirm the potential harmful effects of oxidized fats and the importance of dietary polyphenols in the meal.

Significance of extracapillary proliferation in IgA-nephropathy patients with regard to clinical and histopathological variables

BACKGROUND AND AIM

Extracapillary proliferation (crescent) was not included in the Oxford classification, although previous attempts to correlate the crescent with clinical outcomes have produced conflicting results. In this study, we investigated the clinical and morphological significance of extracapillary proliferation in a group of IgA nephropathy (IgAN) patients with regard to the Oxford classification.

PATIENTS AND METHODS

In an observational study conducted on IgAN patients, we collected a total of 114 biopsies. We diagnosed IgAN by light and immunofluorescence for all patients.

RESULTS

Of the 114 patients, 70.2% were male. The mean age of the patients was 37.7 ± 13.6 years. The mean proteinuria was 1742 ± 1324 mg/day. The mean serum creatinine was 1.6 ± 1.5 mg/dL. Twenty-five (21.9%) patient kidney biopsies had extracapillary proliferation. We found a significant positive correlation between the number of crescents and serum creatinine (p<0.001). Furthermore, we found a positive association between the nephrotic syndrome and the total number of crescents (p<0.05). Additionally, we observed a significant positive correlation between the amount of sclerosed glomeruli and extracapillary proliferation (p=0.028).

CONCLUSION

Our findings confirm that extracapillary proliferation has a significant association with proteinuria and sclerotic glomeruli. We anticipate that extracapillary proliferation will be included in a revision of the Oxford classification of IgAN to widen the scope of the classification.

Renoprotective effects of metformin

Metformin as a biguanid drug entered to the market 50 years ago and now is generally recommended as the first-line treatment in type 2 diabetes, especially in overweight patients, however in recent years new indications for its use have emerged . It improves peripheral and liver sensitivity to insulin, reduces basal hepatic glucose production, increases insulin-stimulated uptake and utilization of glucose by peripheral tissues, decreases hunger and causes weight reduction.Recently, much attention has been made toward the possible kidney protective efficacy of metformin. Recent studies have proven that metformin, possesses antioxidant properties, too.

Association of proteinuria with various clinical findings and morphologic variables of oxford classification in immunoglobulin a nephropathy patients

BACKGROUND

Immunoglobulin A nephropathy (IgAN) with nephrotic syndrome is an uncommon form of IgAN. Clinical and morphological characteristics of proteinuria in IgAN, especially when is in nephrotic range have not yet been fully examined. This study was aimed to correlate morphologic variables of the Oxford classification, and various clinical data with proteinuria in IgAN patients. We also aimed to demonstrate the significance of prevention of proteinuria as one of the important factors in progression of this disease.

METHODS

In an observational study conducted on IgAN patients, total of 114 biopsies were entered in the study. IgAN was diagnosed by light and immunofluorescence study.

RESULTS

Of 114 patients 70.2% were male. Mean age of patients was 37.7 ± 13.6 years. The mean of proteinuria was 1742 ± 1324 mg/day. Also mean of serum creatinine (Cr) was 1.6 ± 1.5 mg/dL. Of 114 patients, 11(9.6%) had nephrotic range proteinuria. In this study, there was a positive correlation between proteinuria and serum Cr, peri-glomerular fibrosis or interstitial fibrosis. There was a positive association between proteinuria and totally sclerotic glomeruli too. There was also a positive association between the amount of fibrous crescents and the level of proteinuria. Nephrotic proteinuria could just be seen in male patients. Also, nephrotic syndrome had a positive association with the number of crescents.

CONCLUSIONS

Our findings firstly support the prognostic value of crescent due to its association with proteinuria and secondly imply the importance of treatment of proteinuria to prevent progression of IgAN.

Efficacy of Co-administration of Garlic Extract and Metformin for Prevention of Gentamicin-Renal Toxicity in Wistar Rats: A Biochemical Study

BACKGROUND

Gentamicin (GM) nephrotoxicity has been related to oxidative stress. Garlic and metformin (MF) have anti-oxadant activity and therefore, this study was aimed to evaluate the preventive and curative effects of garlic, MF and their combination on GM indeced tubular toxicity in Wistar rats.

METHODS

In a pre-clinical study, 70 male Wistar rats were randomly designated into 7 groups of 10 and treated as follows: Group 1: Received saline for 20 days. Group 2: Were injected 100 mg/kg/d of GM intraperitoneally (ip), for 10 days and saline for 10 more days. Group 3: Received GM for 10 days then 20 mg/kg garlic ip for the next 10 days. Group 4: Received GM for 10 days and MF (100 mg/kg) orally for the next 10 days. Group 5: Received GM for 10 days and a combination of MF and garlic for the next 10 days (100 and 20 mg/kg, respectively). Group 6: The same as group 5but with half-doses of MF and Garlic. Group 7: Received GM for 10 days together with a combination ofMF and garlic. On 20(th) day of the experiment the serum blood urea nitrogen (BUN) and creatinine (Cr) were measured and compared in different groups.

RESULTS

GM injection significantly increased the serum BUN and Cr (P < 0.05). Administration of MF, garlic or their combination with or after injection of GM (high doses) could atenuate BUN and Cr.

CONCLUSIONS

The results indicate that MF and garlic or their combination have curative and protective activity against GM nephrotoxicity.

Association of serum uric acid with proteinuria in type 2 diabetic patients

BACKGROUND

Various findings suggest that uric acid is an inflammatory factor and may have a role in endothelial dysfunction and act as a mediator of diabetic nephropathy. The objective of this study was to evaluate the relationships between serum uric acid level and level of proteinuria in type 2 diabetic (T2D) patients.

MATERIALS AND METHODS

A cross-sectional analytical study was conducted in 60 patients with T2D without a history of gout. None was treated with allopurinol. Venous blood samples were obtained in fasting state for determinations of serum creatinine, uric acid, and hemoglobin A1c (HbA1c) (reference range 3.8-5.5%); 24-h urine proteinuria was also measured.

RESULTS

Mean age of the patients was 57 ± 8.3 years. Mean ± standard error (SE) of serum creatinine was 0.98 ± 0.028 mg/dL, mean ± SE of serum uric acid was 4.5 ± 0.15 mg/dL, and mean ± SE of proteinuria was 388 ± 28.7 mg/day (median = 303.5 mg/day). There was no significant difference in serum uric acid, HbA1c, and creatinine level between males and females (P > 0.05). There was a significant positive association between body mass index (BMI) and serum uric acid levels (r = 0.428, P = 0.001). After adjustment for weight, a significant positive association of serum uric acid with level of proteinuria was seen (r = 0.47, P < 0.001).

CONCLUSION

Serum uric acid had a significant positive association with diabetic nephropathy. It might be hypothesized that serum uric acid plays a role in diabetic nephropathy in T2D.