Dietary Antioxidant Supplements and Uric Acid in Chronic Kidney Disease: A Review

Nonlinear relationship between oxidative balance score and hyperuricemia: analyses of NHANES 2007-2018

BACKGROUND

Limited data regarding the correlation between oxidative balance score (OBS) and hyperuricemia highlights the necessity for thorough investigations. This study aims to examine the link between OBS, which incorporates dietary and lifestyle factors, and the occurrence of hyperuricemia.

METHODS

We conducted a cross-sectional study involving 13,636 participants from the 2007-2018 National Health and Nutrition Examination Survey (NHANES). The oxidative balance score (OBS) was determined based on four lifestyle factors and sixteen dietary nutrients. We assessed the levels of serum uric acid (SUA) and the occurrence of hyperuricemia as outcomes. Weighted logistic regression and linear models were used for statistical analysis, using Restricted Cubic Splines (RCS) to examine potential nonlinear associations. Subgroup analysis and sensitivity assessments were performed to identify any variations and ensure the robustness of the findings.

RESULTS

Higher OBS was consistently correlated with decreased SUA levels and a reduced prevalence of hyperuricemia. RCS highlighted a significant negative nonlinear association, particularly in females. Subgroup analysis revealed gender-based differences and interactive correlation, providing additional insights regarding OBS and hyperuricemia relationship.

CONCLUSION

This study underscores a robust negative correlation between OBS and SUA levels as well as the incidence of hyperuricemia, emphasizing the importance of dietary and lifestyle factors. Incorporating RCS, subgroup analysis, and sensitivity assessments enhances the depth of our findings, providing valuable insights for further research.

Effects of silymarin supplementation on liver and kidney functions: A systematic review and dose-response meta-analysis

It is suggested that supplementation with silymarin (SIL) has beneficial impacts on kidney and liver functions. This systematic review and dose-response meta-analysis assessed the impact of SIL administration on certain hepatic, renal, and oxidative stress markers. A systematic search was conducted in various databases to identify relevant trials published until January 2023. Randomized controlled trials (RCTs) that evaluated the effects of SIL on kidney and liver markers were included. A random-effects model was used for the analysis and 41 RCTs were included. The pooled results indicated that SIL supplementation led to a significant reduction in serum levels of alkaline phosphatase, alanine transaminase, creatinine, and aspartate aminotransferase, along with a substantial elevation in serum glutathione in the SIL-treated group compared to their untreated counterparts. In addition, there was a nonsignificant decrease in serum levels of gamma-glutamyl transferase, malondialdehyde (MDA), total bilirubin, albumin (Alb), total antioxidant capacity, and blood urea nitrogen. Sub-group analyses revealed a considerable decline in MDA and Alb serum values among SIL-treated participants with liver disease in trials with a longer duration (≥12 weeks). These findings suggest that SIL may ameliorate certain liver markers with potential hepatoprotective effects, specifically with long-term and high-dose supplementation. However, its nephroprotective effects and impact on oxidative stress markers were not observed. Additional high-quality RCTs with longer durations are required to determine the clinical efficacy of SIL supplementation on renal and oxidative stress markers.

Diazoxide and moderate-intensity exercise improve skeletal muscle function by decreasing oxidants and enhancing antioxidant defenses in hypertensive male rats

High sodium intake is decisive in the incidence increase and prevalence of hypertension, which has an impact on skeletal muscle functionality. Diazoxide is an antihypertensive agent that inhibits insulin secretion and is an opener of KATP channels (adosine triphosphate sensitive potasium channels). For this reason, it is hypothesized that moderate-intensity exercise and diazoxide improve skeletal muscle function by reducing the oxidants in hypertensive rats. Male Wistar rats were assigned into eight groups: control (CTRL), diazoxide (DZX), exercise (EX), exercise + diazoxide (EX + DZX), hypertension (HTN), hypertension + diazoxide (HTN + DZX), hypertension + exercise (HTN + EX), and hypertension + exercise + diazoxide (HTN + EX + DZX). To induce hypertension, the rats received 8% NaCl dissolved in water orally for 30 days; in the following 8 weeks, 4% NaCl was supplied to maintain the pathology. The treatment with physical exercise of moderate intensity lasted 8 weeks. The administration dose of diazoxide was 35 mg/kg intraperitoneally for 14 days. Tension recording was performed on the extensor digitorum longus and the soleus muscle. Muscle homogenates were used to measure oxidants using fluorescent probe and the activity of antioxidant systems. Diazoxide and moderate-intensity exercise reduced oxidants and increased antioxidant defenses.

Fructose-induced hyperuricaemia - protection factor or oxidative stress promoter?

Accumulating evidence suggests that dietary fructose may play a role in the hyperuricaemia development, but the precise mechanism remains unclear. Hyperuricaemia is characterised by excessive production and deposition of urate crystals, and the metabolism of fructose has been implicated in the elevation of serum urate levels. The association between fructose intake and the risk of hyperuricaemia is explained by the metabolism of fructose in the liver, small intestine, and kidney. Many studies have confirmed the correlation between fructose consumption and an increased risk of developing hyperuricaemia, but more prospective studies to fully elucidate the role of fructose intake in the pathogenesis of hyperuricaemia are needed. It is important to note that maintaining a balanced diet, and lifestyle is crucial when considering fructose intake. Limiting the consumption of products high in added sugars and maintaining a healthy weight can contribute to reducing the risk of hyperuricaemia and associated health complications.

Interaction between anemia and hyperuricemia in the risk of all-cause mortality in patients with chronic kidney disease

Aim

Both hyperuricemia and anemia are not only the manifestation of chronic kidney disease (CKD) but also related to its occurrence and development. A recent study has found that there was a synergetic effect between hyperuricemia and anemia on new-onset CKD. Herein we aimed to explore the roles of hyperuricemia and anemia in the all-cause mortality in patients with CKD.

Methods

Data of adult patients with CKD were extracted from the National Health and Nutrition Examination Surveys (NHANES) database in 2009-2018 in this retrospective cohort study. Weighted univariate and multivariate COX regression analyses were used to investigate the associations of hyperuricemia and anemia with all-cause mortality, and the evaluation indexes were hazard ratios (HRs) and 95% confidence intervals (CIs). The interaction effect between hyperuricemia and anemia on the risk of all-cause mortality was assessed via relative excess risk due to interaction (RERI) and attributable proportion of interaction (AP). Subgroup analyses of age, gender, CVD, hypertension, DM, and cancer were also performed to assess this interaction effect.

Results

Among 3,678 eligible patients, 819 died from all causes. After adjusting for covariables, we found that CKD patients with anemia (HR = 1.72, 95%CI: 1.42-2.09) or hyperuricemia (HR = 1.21, 95%CI: 1.01-11.45) had a higher risk of all-cause mortality. There was a potential synergetic effect between anemia and hyperuricemia on all-cause mortality, with RERI of 0.630 and AP of 0.291. Moreover, this synergetic effect was also observed in ≥65 years old (AP = 0.330), male (AP = 0.355), hypertension (AP = 0.736), non-hypertension (AP = 0.281), DM (AP = 0.371), and cancer (AP = 0.391) subgroups.

Conclusion

A potential synergetic effect between anemia and hyperuricemia on all-cause mortality was found in patients with CKD. However, further studies are needed to clarify the causal relationship between them.

Catalpol ameliorates fructose-induced renal inflammation by inhibiting TLR4/MyD88 signaling and uric acid reabsorption

Accumulating evidence suggests that excess fructose uptake induces metabolic syndrome and kidney injury. Here, we primarily investigated the influence of catalpol on fructose-induced renal inflammation in mice and explored its potential mechanism. Treatment with catalpol improved insulin sensitivity and hyperuricemia in fructose-fed mice. Hyperuricemia induced by high-fructose diet was associated with increases in the expressions of urate reabsorptive transporter URAT1 and GLUT9. Treatment with catalpol decreased the expressions of URAT1 and GLUT9. Futhermore, treatment with catalpol ameliorated renal inflammatory cell infiltration and podocyte injury, and these beneficial effects were associated with inhibiting the production of inflammatory cytokines including IL-1β, IL-18, IL-6 and TNF-α. Moreover, fructose-induced uric acid triggers an inflammatory response by activiting NLRP3 inflammasome, which then processes pro-inflammatory cytokines. Treatment with catalpol could inhibit the activation of NLRP3 inflammasome as well. Additionally, TLR4/MyD88 signaling was activated in fructose-fed mice, while treatment with catalpol inhibited this activation along with promoting NF-κB nuclear translocation in fructose-fed mice. Thus, our study demonstrated that catalpol could ameliorate renal inflammation in fructose-fed mice, attributing its beneficial effects to promoting uric acid excretion and inhibit the activation of TLR4/MyD88 signaling.

Development and validation of a prediction model for hyperuricemia risk in hypertensive patients

OBJECTIVE

This study aimed to create a predictive model for hyperuricemia (HUA) in patients diagnosed with hypertension and evaluate its predictive accuracy.

METHODS

Employing a retrospective cohort design, this study investigated HUA incidence and clinical data among 228 patients with essential hypertension selected from the Department of Cardiology at a tertiary A-level hospital in Anhui Province, China, between January 2018 and June 2021. The patients were divided randomly into a training group (168 cases) and a validation group (60 cases) at a 7:3 ratio. The training group underwent univariate and multivariate logistic regression analyses to identify risk factors for HUA. Additionally, an R software-generated nomogram model estimated HUA risk in hypertensive patients. The validation group assessed the nomogram model's discriminatory power and calibration using receiver operating characteristic curve analysis and the Hosmer-Lemeshow goodness-of-fit test.

RESULTS

The study found a 29.39% prevalence of HUA among the 228 participants. Logistic regression analyses identified age, body mass index, and concomitant coronary heart disease as independent HUA risk factors (odds ratio [OR] > 1 and P < 0.05). Conversely, high-density lipoprotein cholesterol emerged as an independent protective factor against HUA in hypertensive patients (OR < 1 and P < 0.05). Using these factors, a nomogram model was constructed to assess HUA risk, with an AUC of 0.873 (95% confidence interval [CI]: 0.818-0.928) in the training group and 0.841 (95% CI: 0.735-0.946) in the validation group, indicating a strong discriminatory ability. The Hosmer-Lemeshow goodness-of-fit test showed no significant deviation between predicted and actual HUA frequency in both groups (χ2 = 5.980, 9.780, P = 0.649, 0.281), supporting the nomogram's reliability.

CONCLUSION

The developed nomogram model, utilizing independent risk factors for HUA in hypertensive patients, exhibits strong discrimination and calibration. It holds promise as a valuable tool for cardiovascular professionals in clinical decision-making.

The Association Between the Composite Dietary Antioxidant Index and Frailty Symptoms: Mediating Effects of Oxidative Stress

Background

There is growing evidence that an antioxidant diet is a protective factor against frailty. However, few studies have examined the effect of comprehensive dietary antioxidants on frailty symptoms. The aim of this study was to examine the relationships between the composite dietary antioxidant index (CDAI) and frailty and the underlying mechanisms involved.

Methods

Based on the National Health and Nutrition Survey (NHANES) 2003-2018, this study included 11,277 older persons aged ≥60 years. In this study, frailty was defined as having a total score >0.21 on the 49-item frailty index. Six dietary antioxidants were selected for use in calculating the CDAI. A weighted multiple logistic regression model with subgroup analysis and restricted cubic splines (RCSs) were used to examine the association between the CDAI and frailty. To examine the role of oxidative stress, mediation analyses were also conducted.

Results

The association between the CDAI score and frailty risk was significant according to the multivariate model. Compared with participants in tertile 1, participants in both tertile 2 and tertile 3 had lower odds of developing frailty symptoms (OR=0.86; 95% CI=0.75-0.97; P=0.02; and OR=0.81; 95% CI=0.70-0.93; P=0.003). According to the subgroup analyses, the differences in interactions were not statistically significant. There was also a potential nonlinear relationship between the CDAI score and frailty risk. The serum albumin concentration and uric acid concentration had significant mediating effects on the association between the CDAI score and frailty index, with 19.25% (P=0.002) and 21.26% (P < 0.001) of the total, respectively.

Conclusion

Frailty is negatively associated with the CDAI score, which may be partially mediated by oxidative stress.

Eupatilin inhibits xanthine oxidase in vitro and attenuates hyperuricemia and renal injury in vivo

Uric acid (UA) is the final metabolite of purines in the liver that can cause hyperuricemia at high levels. The kidneys are the main excretory organs for UA. The excessive accumulation of UA in the kidneys causes the development of hyperuricemia that often leads to renal injury. Eupatilin (Eup) is a flavonoid natural product that possesses various pharmacological properties such as antioxidant, anti-cancer, and anti-inflammatory. We were interested in exploring the potential role of Eup in lowering UA and nephroprotective. We initially investigated the effects of Eup on xanthin oxidase (XOD) activity in vitro, followed by investigating its ability to lower UA levels, anti-inflammatory effects, nephroprotective effects, and the underlying mechanisms using hyperuricemia rats sustained at high UA level. The results showed that Eup had an inhibitory effect on XOD activity in vitro and significantly reduced serum UA, creatinine, BUN, IL-1β and IL-6 levels in hyperuricemic rats, ameliorating inflammation, renal oxidative stress and pathological injury. Furthermore, Eup inhibited ADA and XOD enzyme activities in the liver and serum and modulated GLUT9, URAT1 and ABCG2 protein expression in the kidneys and ileum. Our findings provide a scientific basis for suggesting Eup as an option for a potential treatment for hyperuricemia.

Association between the composite dietary antioxidant index and chronic kidney disease: evidence from NHANES 2011-2018

Objectives: There is growing evidence that antioxidant-rich diets protect against chronic kidney disease (CKD). However, the relationship between the Composite Dietary Antioxidant Index (CDAI), an important measure of an antioxidant diet, and CKD has received little attention. Therefore, here we investigated the relationship between the CDAI and CKD through a cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) 2011-2018 data. Methods: The CDAI was calculated based on the intake of six dietary antioxidants. A survey-based multivariate linear regression analysis was performed to analyze the independent relationship between the CDAI and CKD. Weighted multivariate regression and subgroup analyses were conducted to explore the relationship between the CDAI and CKD. Results: A total of 6874 NHANES participants represented 181.9 million non-institutionalized US residents (mean age, 46.43 ± 0.38 years; 49.87% female; 40.62% non-Hispanic white; 20.24% non-Hispanic black; and 13.94% Mexican American). The weighted linear regression model with full adjustment for confounding variables was -0.0155 (-0.0417, 0.0107) for Q2 (P for trend <0.0001), -0.0052 (-0.0346, 0.0242) for Q3 (P for trend <0.0001), and -0.0305 (-0.0491, -0.0120) for Q4 (P for trend = 0.0094) upon comparison with the lowest quartile of the CDAI. None of the interactions in any subgroup analysis were statistically significant except for individuals with a history of diabetes or the aged population (≥60 years) (P for interaction <0.05). Conclusions: The CDAI was positively associated with a lower prevalence of CKD in adults in the United States. Further large-scale prospective studies are required to analyze the role of the CDAI in CKD.

Higher serum uric acid is associated with body fat, retinol-binding protein 4, and antioxidative status in Brazilian children

OBJECTIVE

The aim of this study was to evaluate the association of serum uric acid (SUA) with adiposity, adipokines, and anti- and oxidative markers in Brazilian children.

METHODS

This was a cross-sectional investigation with 378 children ages 8 to 9 y in Viçosa, Minas Gerais, Brazil. Information on sociodemographic and lifestyle characteristics was obtained via questionnaires, and body fat was determined by dual energy x-ray absorptiometry. We compared the distributions of adiposity (total and central), adipokines (adiponectin, chemerin, leptin, and retinol-binding protein 4 [RBP4]), anti- and oxidative markers (plasma ferric reducing antioxidant power [FRAP], superoxide dismutase [SOD], and malondialdehyde [MDA]) by SUA categories using linear regression.

RESULTS

SUA was positively associated with total and central fat. Every standard deviation (SD) of SUA was related, respectively, to a 3.4 (95% confidence interval [CI], 2.4-4.4), 4 (95% CI, 2.8-5.1), 4.2 (95% CI, 2.9-5.5), and 3.5 (95% CI, 2.4-4.6) units higher of total, truncal, android, and gynoid fat. We found a positive association of SUA with RBP4 and FRAP, and a negative association with MDA. Every SD of SUA was related, respectively, to 0.1 (95% CI, 0.01-0.1) and 7.8 (95% CI, 5.5-10.1) units higher of RBP4 and FRAP; and to -0.3 (95% CI, -0.5 to -0.1) units lower of MDA.

CONCLUSIONS

SUA was positively associated with adiposity, RBP4, and antioxidative status in Brazilian children.

Composite Dietary Antioxidant Index Is Negatively Associated with Hyperuricemia in US Adults: An Analysis of NHANES 2007-2018

Hyperuricemia and its complications are severe risks to human health. Dietary intervention is considered an essential part of the management of hyperuricemia. Studies have reported that the intake of antioxidants has a positive effect on hyperuricemia. Here, we collected data from 8761 participants of the National Health and Nutrition Examination Survey for this analysis. Daily intakes of vitamins A, C, and E; manganese; selenium; and zinc were calculated as the composite dietary antioxidant index (CDAI). The participants were divided into four groups (Q1, Q2, Q3, and Q4) according to the CDAI. Univariate analysis was used to assess the association of covariates with hyperuricemia. The association between the CDAI and hyperuricemia was evaluated using multinomial logistic regression, and its stability was determined by stratified analysis. Our results revealed that the CDAI has a significant negative association with hyperuricemia (Q2: 0.81 (0.69, 0.95); Q3: 0.75 (0.62, 0.90); Q4: 0.65 (0.51, 0.82); P < 0.01). The results of stratified analysis emphasize that this association between CDAI and hyperuricemia is stable. In conclusion, this study suggested a negative association between the CDAI and hyperuricemia.

Fucoidan from Saccharina japonica Alleviates Hyperuricemia-Induced Renal Fibrosis through Inhibiting the JAK2/STAT3 Signaling Pathway

Fucoidan is a native sulfated polysaccharide mainly isolated from brown seaweed, with diverse pharmacological activities, such as anti-inflammatory and antifibrosis. Hyperuricemia (HUA) is a common metabolic disease worldwide and mainly causes hyperuricemic nephropathy, including chronic kidney disease and end-stage renal fibrosis. The present study investigated the protective function of fucoidan in renal fibrosis and its pharmacological mechanism. The renal fibrotic model was established with the administration of potassium oxonate for 10 weeks. The protein levels of related factors were assessed in HUA mice by an enzyme-linked immunosorbent assay (ELISA) and western blotting. The results showed that fucoidan significantly reduced the levels of serum uric acid, blood urea nitrogen (BUN), α-smooth muscle actin (α-SMA), and collagen I, and improved kidney pathological changes. Furthermore, renal fibrosis had been remarkably elevated through the inhibition of the epithelial-to-mesenchymal transition (EMT) progression after fucoidan intervention, suppressing the Janus kinase 2 (JAK2) signal transducer and activator of transcription protein 3 (STAT3) signaling pathway activation. Together, this study provides experimental evidence that fucoidan may protect against hyperuricemia-induced renal fibrosis via downregulation of the JAK2/STAT3 signaling pathway.

Quantitative, Targeted Analysis of Gut Microbiota Derived Metabolites Provides Novel Biomarkers of Early Diabetic Kidney Disease in Type 2 Diabetes Mellitus Patients

Diabetic kidney disease (DKD) is one of the most debilitating complications of type 2 diabetes mellitus (T2DM), as it progresses silently to end-stage renal disease (ESRD). The discovery of novel biomarkers of early DKD becomes acute, as its incidence is reaching catastrophic proportions. Our study aimed to quantify previously identified metabolites from serum and urine through untargeted ultra-high-performance liquid chromatography coupled with electrospray ionization-quadrupole-time of flight-mass spectrometry (UHPLC-QTOF-ESI+-MS) techniques, such as the following: arginine, dimethylarginine, hippuric acid, indoxyl sulfate, p-cresyl sulfate, L-acetylcarnitine, butenoylcarnitine and sorbitol. The study concept was based on the targeted analysis of selected metabolites, using the serum and urine of 20 healthy subjects and 90 T2DM patients with DKD in different stages (normoalbuminuria-uACR < 30 mg/g; microalbuminuria-uACR 30-300 mg/g; macroalbuminuria-uACR > 300 mg/g). The quantitative evaluation of metabolites was performed with pure standards, followed by the validation methods such as the limit of detection (LOD) and the limit of quantification (LOQ). The following metabolites from this study resulted as possible biomarkers of early DKD: in serum-arginine, dimethylarginine, hippuric acid, indoxyl sulfate, butenoylcarnitine and sorbitol and in urine-p-cresyl sulfate.

Evaluation of anti-hyperuricemic effects of Alocasia longiloba Miq. (Keladi Candik) extracts in potassium oxonate induced rat model

Hyperuricemia has become a significant public-health concern in recent years, and the available treatments have been reported to have an adverse side effect on patients. Alocasia longiloba has been used traditionally in Malaysia for treating gout, inflammation, and wounds. However, the plant has not been investigated for its effects on hyperuricemia. This study investigated the anti-hyperuricemic and anti-inflammatory effects of A. longiloba extracts in hyperuricemic rats induced by potassium oxonate (250 mg/kg body weight). Rats were given A. longiloba extracts or a standard drug for two-week, and blood and tissue samples were collected for analysis. Results show that A. longiloba extracts significantly reduced serum uric acid levels in hyperuricemic rats and inhibited xanthine oxidase (XOD) activity in the liver and kidney, which could be the mechanism underlying the urate-lowering effects. The extracts also significantly (p < 0.05) reduced the levels of proinflammatory cytokines (IL-18 and IL-1β) in serum samples and had hepatoprotective and nephroprotective effects in hyperuricemic rats. The study supports the use of A. longiloba as a complementary therapy for treating hyperuricemia.

Accumulation of Renal Fibrosis in Hyperuricemia Rats Is Attributed to the Recruitment of Mast Cells, Activation of the TGF-β1/Smad2/3 Pathway, and Aggravation of Oxidative Stress

Renal fibrosis is relentlessly progressive and irreversible, and a life-threatening risk. With the continuous intake of a high-purine diet, hyperuricemia has become a health risk factor in addition to hyperglycemia, hypertension, and hyperlipidemia. Hyperuricemia is also an independent risk factor for renal interstitial fibrosis. Numerous studies have reported that increased mast cells (MCs) are closely associated with kidney injury induced by different triggering factors. This study investigated the effect of MCs on renal injury in rats caused by hyperuricemia and the relationship between MCs and renal fibrosis. Our results reveal that hyperuricemia contributes to renal injury, with a significant increase in renal MCs, leading to renal fibrosis, mitochondrial structural disorders, and oxidative stress damage. The administration of the MCs membrane stabilizer, sodium cromoglycate (SCG), decreased the expression of SCF/c-kit, reduced the expression of α-SMA, MMP2, and inhibited the TGF-β1/Smad2/3 pathway, thereby alleviating renal fibrosis. Additionally, SCG reduced renal oxidative stress and mitigated mitochondrial structural damage by inhibiting Ang II production and increasing renal GSH, GSH-Px, and GR levels. Collectively, the recruitment of MCs, activation of the TGF-β1/Smad2/3 pathway, and Ang II production drive renal oxidative stress, ultimately promoting the progression of renal fibrosis in hyperuricemic rats.

Untargeted metabonomic analysis of non-alcoholic fatty liver disease with iron overload in rats via UPLC/MS

BACKGROUND/AIMS

In recent years, many metabolites specific to nonalcoholic fatty liver disease (NAFLD) have been identified thanks to the application of metabolomics techniques. This study aimed to investigate the candidate targets and potential molecular pathways involved in NAFLD in the presence of iron overload.

METHODS

Male Sprague Dawley rats were fed with control or high-fat diet with or without excess iron. After 8,16,20 weeks of treatment, urine samples of rats were collected for metabolomics analysis using ultra-performance liquid chromatography/mass spectrometry (UPLC-MS). Blood and liver samples were also collected.

RESULTS

High-fat, high-iron diet resulted in increased triglyceride accumulation and increased oxidative damage. A total of 13 metabolites and four potential pathways were identified. Compared to the control group, the intensities of adenine, cAMP, hippuric acid, kynurenic acid, xanthurenic acid, uric acid, and citric acid were significantly lower (P < 0.05) and the concentration of other metabolites was significantly higher in the high-fat diet group. In the high-fat, high-iron group, the differences in the intensities of the above metabolites were amplified.

CONCLUSION

Our findings suggest that NAFLD rats have impaired antioxidant system and liver function, lipid disorders, abnormal energy, and glucose metabolism, and that iron overload may further exacerbate these disorders.

Lactobacillus gasseri LG08 and Leuconostoc mesenteroides LM58 exert preventive effect on the development of hyperuricemia by repairing antioxidant system and intestinal flora balance

Introduction

Currently, hyperuricemia has shown a surprisingly rising trend, which attracts widespread attention due to potentially major health risks. Considering the inevitable side effects of long-term medicine, probiotics are emerging as potential therapeutics due to their ability to improve uric acid metabolism and superior safety.

Methods

In our study, two strains of probiotics, Lactobacillus gasseri LG08 (LG08) and Leuconostoc mesenteroides LM58 (LM58) isolated from kimchi were evaluated for the prebiotic properties in vitro and uric-lowering effects in vivo. Here, hyperuricemia animal model and 16S rRNA gene amplicons analysis were further studied to investigate whether these probiotics exert different effects in prevention and treatment.

Results

In vivo indicators and intestinal flora immunity revealed that both LG08 and LM58 significantly prevent the development and progression of hyperuricemia, repair the antioxidant system and maintain intestinal flora balance in healthy rats, especially LM58. After hyperuricemia was formed, although the effect of LG08 and LM58 could decrease the level of uric acid, the effect to reverse and repair antioxidant levels in the body was limited.

Discussion

In our study, these findings have important implications for hyperuricemia prevention and therapy, and provided more mechanistic insights into the effect of probiotics in hyperuricemia.

Research on the Efficacy of Ganpu Vine Tea in Inhibiting Uric Acid Production

Ganpu vine tea is a new type of health care citrus fruit tea made from citrus shell, Pu-er tea, and vine tea baked as raw materials. In this study, the in vitro uric acid synthase inhibition system and hyperuric acid cell model were constructed to appraise the uric acid lowering efficacy of Ganpu vine tea, traditional Ganpu tea, and vine tea. Results showed that in the uric acid synthase inhibition system, the aqueous extract can inhibite the puric metabolically related enzymes, such as adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), and xanthine oxidase (XOD). The ability of the aqueous extract to inhibit the above enzyme was as follows: vine tea > Ganpu vine tea > Ganpu tea; all teas had a strong effect on XOD inhibition. The hyperuric acid cell model test showed that the aqueous extract inhibited uric acid production through accumulating inosine and hypoxanthine and hindering xanthine synthesis. The uric acid reductive ability was as follows: Vine tea > Ganpu vine tea > Ganpu tea. The inhibition of enzymes related to uric acid synthesis and the inhibition of uric acid production were significantly enhanced through adding vine tea to Ganpu tea. It also shows that flavonoids are the main factor driving this ability because they are the main active ingredients in these botanical drinks.

Epigallocatechin-3-Gallate Attenuates Myocardial Dysfunction via Inhibition of Endothelial-to-Mesenchymal Transition

Cardiac tissue damage following ischemia leads to cardiomyocyte apoptosis and myocardial fibrosis. Epigallocatechin-3-gallate (EGCG), an active polyphenol flavonoid or catechin, exerts bioactivity in tissues with various diseases and protects ischemic myocardium; however, its association with the endothelial-to-mesenchymal transition (EndMT) is unknown. Human umbilical vein endothelial cells (HUVECs) pretreated with transforming growth factor β2 (TGF-β2) and interleukin 1β (IL-1β) were treated with EGCG to verify cellular function. In addition, EGCG is involved in RhoA GTPase transmission, resulting in reduced cell mobility, oxidative stress, and inflammation-related factors. A mouse myocardial infarction (MI) model was used to confirm the association between EGCG and EndMT in vivo. In the EGCG-treated group, ischemic tissue was regenerated by regulating proteins involved in the EndMT process, and cardioprotection was induced by positively regulating apoptosis and fibrosis of cardiomyocytes. Furthermore, EGCG can reactivate myocardial function due to EndMT inhibition. In summary, our findings confirm that EGCG is an impact activator controlling the cardiac EndMT process derived from ischemic conditions and suggest that supplementation with EGCG may be beneficial in the prevention of cardiovascular disease.

Perinatal Oxidative Stress and Kidney Health: Bridging the Gap between Animal Models and Clinical Reality

Oxidative stress arises when the generation of reactive oxygen species or reactive nitrogen species overwhelms antioxidant systems. Developing kidneys are vulnerable to oxidative stress, resulting in adult kidney disease. Oxidative stress in fetuses and neonates can be evaluated by assessing various biomarkers. Using animal models, our knowledge of oxidative-stress-related renal programming, the molecular mechanisms underlying renal programming, and preventive interventions to avert kidney disease has grown enormously. This comprehensive review provides an overview of the impact of perinatal oxidative stress on renal programming, the implications of antioxidant strategies on the prevention of kidney disease, and the gap between animal models and clinical reality.

Flavonoid extract of saffron by-product alleviates hyperuricemia via inhibiting xanthine oxidase and modulating gut microbiota

Hyperuricemia was associated with the overproduction or inadequate excretion of uric acid, while its association with gut microbiota has emerged although few studies were focused on it. Previously, we have reported a flavonoid extract from saffron floral bio-residues lowered uric acid in potassium oxonate-induced hyperuricemic mice. In this study, the impacts of the flavonoid extract on potassium oxonate-induced hyperuricemic rats were evaluated through its effects on serum, renal, intestinal uric acid, and xanthine oxidase activity. At the same time, the microbial and metabolic features of the flavonoid extract against hyperuricemia were explored using 16S rRNA sequencing techniques and serum metabolomics, respectively. According to the results, the flavonoid extract lowered serum and intestinal uric acid levels in hyperuricemic rats without kidney damage. On the one hand, it inhibited serum and liver xanthine oxidase activities and down-regulated the expression of hepatic xanthine oxidase. On the other hand, it ameliorated the hyperuricemia-associated gut microbiota dysbiosis and alleviated the disturbance of serum metabolome, especially of lipid and amino acid metabolites. The results suggested that the flavonoid extract of saffron floral bio-residues exerts a potent antihyperuricemia effect by inhibiting xanthine oxidase to decrease uric acid production and modulating gut microbiota related to host metabolism.

Citrus Bergamia and Cynara Cardunculus Reduce Serum Uric Acid in Individuals with Non-Alcoholic Fatty Liver Disease

Background and Objectives: Hyperuricemia and liver steatosis are risk factors for cardiovascular diseases and mortality. The use of natural compounds could be a safe and effective alternative to drugs for the treatment of fatty liver and hyperuricemia. Polyphenolic fraction of Citrus Bergamia in association with the extract of Cynara Cardunculus, as nutraceutical, is able to reduce body weight, hepatic steatosis and markers of oxidative stress. Then, we performed a secondary analysis of a double-blind placebo-controlled trial to examine the effects of this nutraceutical on serum uric acid levels in adults with fatty liver. Materials and Methods: The study included 94 individuals with hepatic steatosis. For six weeks, the intervention group was given a nutraceutical (300 mg/day) comprising a Bergamot polyphenol fraction and Cynara Cardunculus extract. The control group received a daily pill of placebo. Serum uric acid, lipids, glucose and anthropometric parameters were assessed at baseline and after 6 weeks. Results: We found a greater reduction in serum uric acid in the participants taking the nutraceutical rather than placebo (−0.1 ± 0.7 mg/dL vs. 0.3 ± 0.7 mg/dL, p = 0.004), and especially in those with moderate/severe hepatic steatosis also after adjustment for confounding variables. In addition, we analysed the two groups according to tertiles of uric acid concentration. Among participants taking the nutraceutical, we found in those with the highest baseline serum uric acid (>5.4 mg/dL) the greater reduction compared to the lowest baseline uric acid (−7.8% vs. +4.9%; adjusted p = 0.04). The stepwise multivariable analysis confirmed the association between the absolute serum uric acid change and nutraceutical treatment (B = −0.43; p = 0.004). Conclusions: A nutraceutical containing bioactive components from bergamot and wild cardoon reduced serum uric acid during 6 weeks in adults with fatty liver. Future investigations are needed to evaluate the efficacy of this nutraceutical in the treatment of hyperuricaemia.

Caffeine and Its Antioxidant Properties-It Is All about Dose and Source

Caffeine is the most frequently used substance with a central nervous system stimulant effect, but its consumption is most often due to the intake of foods and drinks that contain it (coffee, tea, chocolate, food supplements with plant extracts of Guarana, Mate herba, Cola nuts). Due to its innocuity, caffeine is a safe xanthine alkaloid for human consumption in a wide range of doses, being used for its central nervous stimulating effect, lipolytic and diuresis-enhancing properties, but also as a permitted ergogenic compound in athletes. In addition to the mechanisms that explain the effects of caffeine on the targeted organ, there are many proposed mechanisms by which this substance would have antioxidant effects. As such, its consumption prevents the occurrence/progression of certain neurodegenerative diseases as well as other medical conditions associated with increased levels of reactive oxygen or nitrogen species. However, most studies that have assessed the beneficial effects of caffeine have used pure caffeine. The question, therefore, arises whether the daily intake of caffeine from food or drink has similar benefits, considering that in foods or drinks with a high caffeine content, there are other substances that could interfere with this action, either by potentiating or decreasing its antioxidant capacity. Natural sources of caffeine often combine plant polyphenols (phenol-carboxylic acids, catechins) with known antioxidant effects; however, stimulant drinks and dietary supplements often contain sugars or artificial sweeteners that can significantly reduce the effects of caffeine on oxidative stress. The objective of this review is to clarify the effects of caffeine in modulating oxidative stress and assess these benefits, considering the source and the dose administered.

Exercise serum regulates uric acid transporters in normal rat kidney cells

Hyperuricemia (HUA) refers to a physiological condition of high serum uric acid (SUA) level in the body, which may cause an increased risk of several chronic diseases. The kidney's impaired uric acid (UA) metabolism is an important reason for HUA. In this study, we tested the hypothesis that circulating factors produced during exercise regulate the expression of ABCC4, ABCG2, URAT1, and GLUT9 in normal rat kidneys and normal rat kidney cells (NRK-52E) and their relationship with NF-κB and NRF-2. NRK-52E cells were separately cultured by serum from 10 healthy SD rats who did not exercise (CON) and 10 healthy SD rats who did aerobic treadmill exercise for 6 weeks. Cells cultured by serum from rats who did aerobic treadmill exercise for 6 weeks were separated by without NRF-2 inhibitor (EXE) and with NRF-2 inhibitor (EXE + ML). SUA level of rats was tested by using dry chemical assays, xanthine oxidase (XOD) activity in serum and liver were tested by using enzyme colorimetry assays, protein expression in kidney and NRK-52E cells were tested by using Western-blot, and UA levels in the upper or lower chamber were tested by colorimetry assays. Aerobic exercise reduced SUA levels in rats but did not significantly affect on liver xanthine oxidase. It also increased the expression of some UA transporters in the kidney and NRK-52E cells and increased the cells' ability in UA excretion. When the NRF-2 was inhibited, the NF-κB and ABCG2 increased, and the expression of ABCC4, URAT1, and GLUT9 decreased. In conclusion, this study suggested that 6 weeks of aerobic treadmill exercise intervention may help to improve the excretion of UA in renal cells, suggesting that long-term aerobic exercise may be a means to prevent hyperuricemia.

Establishment and evaluation of a risk-prediction model for hypertension in elderly patients with NAFLD from a health management perspective

Elderly patients with nonalcoholic fatty liver disease are at a higher risk of developing. This study established an effective, individualised, early Hypertension risk-prediction model and proposed health management advice for patients over 60 years of age with NAFLD. Questionnaire surveys, physical examinations, and biochemical tests were conducted in 11,136 participants. The prevalence of NAFLD among 11,136 participants was 52.1%. Risk factors were screened using the least absolute shrinkage and selection operator model and random forest model. A risk-prediction model was established using logistic regression analysis and a dynamic nomogram was drawn. The model was evaluated for discrimination, calibration, and clinical applicability using receiver operating characteristic curves, calibration curves, decision curve analysis, net reclassification index (NRI), and external validation. The results suggested that the model showed moderate predictive ability. The area under curve (AUC) of internal validation was 0.707 (95% CI: 0.688-0.727) and the AUC of external validation was 0.688 (95% CI: 0.672-0.705). The calibration plots showed good calibration, the risk threshold of the decision curve was 30-56%, and the NRI value was 0.109. This Hypertension risk factor model may be used in clinical practice to predict the Hypertension risk in NAFLD patients.

The Effect of Polyphenols on Kidney Disease: Targeting Mitochondria

Mitochondrial function, including oxidative phosphorylation (OXPHOS), mitochondrial biogenesis, and mitochondria dynamics, are essential for the maintenance of renal health. Through modulation of mitochondrial function, the kidneys are able to sustain or recover acute kidney injury (AKI), chronic kidney disease (CKD), nephrotoxicity, nephropathy, and ischemia perfusion. Therapeutic improvement in mitochondrial function in the kidneys is related to the regulation of adenosine triphosphate (ATP) production, free radicals scavenging, decline in apoptosis, and inflammation. Dietary antioxidants, notably polyphenols present in fruits, vegetables, and plants, have attracted attention as effective dietary and pharmacological interventions. Considerable evidence shows that polyphenols protect against mitochondrial damage in different experimental models of kidney disease. Mechanistically, polyphenols regulate the mitochondrial redox status, apoptosis, and multiple intercellular signaling pathways. Therefore, this review attempts to focus on the role of polyphenols in the prevention or treatment of kidney disease and explore the molecular mechanisms associated with their pharmacological activity.

The Role of Antioxidants in the Interplay between Oxidative Stress and Senescence

Cellular senescence is an irreversible state of cell cycle arrest occurring in response to stressful stimuli, such as telomere attrition, DNA damage, reactive oxygen species, and oncogenic proteins. Although beneficial and protective in several physiological processes, an excessive senescent cell burden has been involved in various pathological conditions including aging, tissue dysfunction and chronic diseases. Oxidative stress (OS) can drive senescence due to a loss of balance between pro-oxidant stimuli and antioxidant defences. Therefore, the identification and characterization of antioxidant compounds capable of preventing or counteracting the senescent phenotype is of major interest. However, despite the considerable number of studies, a comprehensive overview of the main antioxidant molecules capable of counteracting OS-induced senescence is still lacking. Here, besides a brief description of the molecular mechanisms implicated in OS-mediated aging, we review and discuss the role of enzymes, mitochondria-targeting compounds, vitamins, carotenoids, organosulfur compounds, nitrogen non-protein molecules, minerals, flavonoids, and non-flavonoids as antioxidant compounds with an anti-aging potential, therefore offering insights into innovative lifespan-extending approaches.

High serum uric acid trajectories are associated with risk of myocardial infarction and all-cause mortality in general Chinese population

Background

Long-term patterns of serum uric acid (SUA) and their association with the risk of myocardial infarction (MI) and mortality are poorly characterized as prior studies measured SUA at a single time point. This study aimed to identify SUA trajectories and determine their associations with incident MI and all-cause mortality.

Methods

We included 85,503 participants who were free of MI in or prior 2012 from the Kailuan study. SUA trajectories during 2006–2012 were identified by group-based trajectory modeling. Cox proportional hazard models were used to assess the association of SUA trajectories with MI and all-cause mortality.

Results

We identified three SUA trajectories during 2006–2012: low-stable (n=44,124, mean SUA: 236–249 μmol/L), moderate-stable (n=34,431, mean SUA: 324–354 μmol/L) and high-stable (n=6,984, mean SUA: 425–463 μmol/L). During a median follow-up of 6.8 years, we documented 817 (0.96%) incident MI and 6498 (7.60%) mortality. Compared with the low-stable group, high-stable group experienced a higher risk of MI (hazard ratio [HR], 1.35; 95% confidence [CI], 1.07–1.71) and all-cause mortality (HR, 1.22; 95% CI, 1.12–1.33). Multiple sensitivity analyses yielded similar results. Additionally, the association of SUA trajectory with MI and all-cause mortality was more pronounced in individuals without a history of hypertension (P-interaction=0.0359) and those aged <60 years (P-interaction<0.0001), respectively.

Conclusions

Higher SUA trajectories were associated with altered risk of MI and all-cause mortality, suggesting that monitoring SUA trajectory may assist in identifying subpopulations at higher risk of MI and all-cause mortality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02812-y.

Vitamin E‑coated dialyzer alleviates erythrocyte deformability dysfunction in patients with end‑stage renal disease undergoing hemodialysis

Patients with end-stage renal disease (ESRD) are characterized by augmented oxidative stress (OS) due to the imbalance between the generation of increased concentrations of oxidative molecules and decreased antioxidant capacity. Vitamin E-coated dialyzer membranes (VEMs) have previously been reported to alleviate the imbalance of redox metabolism in patients with ESRD undergoing hemodialysis (HD); however, their effect on the deformability of red blood cells (RBCs) remains unknown. In the present study, 48 patients with ESRD undergoing HD were enrolled and randomly assigned into two groups: HD with VEMs (VEM group; n=24) and HD with polysulfone dialyzer membranes (PM group; n=24), and another 24 healthy volunteers served as the control group. The present study investigated the morphological changes and deformability of RBCs in patients with ESRD and healthy volunteers. The concentration of serum vitamin E, the parameters of antioxidant stress and OS, and the degree of oxidative phosphorylation and clustering of anion exchanger 1 (Band 3) in RBCs were measured. The results obtained suggested that VEM treatment markedly ameliorated the abnormalities of RBC morphology and deformability in patients with ESRD undergoing HD. Mechanistic studies showed that VEM treatment led to a marked improvement in the concentration of serum vitamin E, which was positively associated with the restored antioxidant capacity, and decreased oxidative phosphorylation and clustering of Band 3 in RBCs of patients with ESRD undergoing HD. Taken together, the results of the present study have demonstrated that VEM treatment effectively restored the imbalance of redox metabolism, and improved the oxidative phosphorylation and clustering of Band 3 in RBCs of patients with ESRD undergoing HD via delivering vitamin E, which may alleviate the abnormal morphological and mechanical properties of RBCs. These findings are anticipated to be useful with respect to improving the nursing care and cure rate of patients with ESRD.

Uric Acid and Oxidative Stress-Relationship with Cardiovascular, Metabolic, and Renal Impairment

Background: The connection between uric acid (UA) and renal impairment is well known due to the urate capacity to precipitate within the tubules or extra-renal system. Emerging studies allege a new hypothesis concerning UA and renal impairment involving a pro-inflammatory status, endothelial dysfunction, and excessive activation of renin–angiotensin–aldosterone system (RAAS). Additionally, hyperuricemia associated with oxidative stress is incriminated in DNA damage, oxidations, inflammatory cytokine production, and even cell apoptosis. There is also increasing evidence regarding the association of hyperuricemia with chronic kidney disease (CKD), cardiovascular disease, and metabolic syndrome or diabetes mellitus. Conclusions: Important aspects need to be clarified regarding hyperuricemia predisposition to oxidative stress and its effects in order to initiate the proper treatment to determine the optimal maintenance of UA level, improving patients’ long-term prognosis and their quality of life.

Serum uric acid level and all-cause and cardiovascular mortality in peritoneal dialysis patients: A systematic review and dose-response meta-analysis of cohort studies

BACKGROUND

The association between serum uric acid (SUA) and all-cause and cardiovascular disease (CVD) mortality in peritoneal dialysis (PD) patients is controversial. Therefore, we aimed to determine the relationship between SUA and all-cause and CVD mortality in PD patients.

METHOD

Web of Science, EMBASE, PubMed and the Cochrane Library databases were searched from their inception to 7 April 2021. Effect estimates were presented as hazard ratios (HRs) with 95% confidence intervals (95% CIs) and pooled using random effects model.

RESULT

Thirteen cohort studies with 22418 patients were included in this systematic review, of which 9 were included in the meta-analysis. Before switching the reference group, pooled result for the highest SUA category was significantly greater than the median for all-cause mortality (HR = 2.41, 95% CI: 1.37-4.26). After switching the reference group, the highest SUA category did not demonstrate an increased all-cause (HR = 1.40, 95% CI: 0.95-2.05) or CVD (HR = 1.30, 95% CI: 0.72-2.34) mortality compared with the lowest SUA category. Dose-response analysis suggested a nonlinear association between SUA and all-cause mortality risk (Pnonlinearity = 0.002).

CONCLUSION

This meta-analysis didn't find the relationship between SUA levels and all-cause and CVD mortality risk in PD patients. More rigorously designed studies are warranted in the future.

Association Between Low-Level Blood Cadmium Exposure and Hyperuricemia in the American General Population: a Cross-sectional Study

Heavy metals, including cadmium, are suspected to increase serum uric acid levels and hyperuricemia in both gender, but the evidences about this are inconclusive. To determine whether serum cadmium in American adults(≥19 years old) is associated with uric acid levels and risk of hyperuricemia, 2620 participants from the US National Health and Nutrition Examination Survey were recruited. Hyperuricemia was defined as a serum UA concentration ≥ 416.4 μmol/L for men and ≥ 356.9 μmol/L for women. Regression analyses were used to analyze the association of cadmium with serum UA and hyperuricemia. The threshold effect explored using two-piecewise linear regression model by the smoothing plot. The overall median of blood cadmium was 0.27 μg/L in men and 0.33μg/L in women. After adjusting for the covariates (race; age; education; BMI; smoke status; alcohol consumption; blood lead; hypertension; diabetes mellitus; hemoglobin; eGFR; triglyceride; and cholesterol), a non-linear relationship between hyperuricemia and cadmium among men was detected; and there was a positive line correlation between them for women (OR = 1.58; 95%CI (1.08, 2.31)). No significant association between uric acid and cadmium in either gender was found. Blood cadmium levels in the range currently considered acceptable were positively associated with increased prevalence of hyperuricemia in women, but inversely associated in men (cadmium <0.77μg/L).

Protective Effect of Luminal Uric Acid Against Indomethacin-Induced Enteropathy: Role of Antioxidant Effect and Gut Microbiota

BACKGROUND

Uric acid (UA) has anti- and pro-inflammatory properties. We previously revealed that elevated serum UA levels provide protection against murine small intestinal injury probably via luminal UA secreted in the small intestine. Luminal UA may act as an antioxidant, preventing microbiota vulnerability to oxidative stress. However, whether luminal UA is increased under hyperuricemia and plays a protective role in a dose-dependent manner as well as the mechanism by which luminal UA exerts its protective effects on enteropathy remains unknown.

METHODS

Inosinic acid (IMP) (1000 mg/kg, i.p.) was administered to obtain high serum UA (HUA) and moderate serum UA (500 mg/kg IMP, i.p.) mice. UA concentrations and levels of oxidative stress markers in the serum and intestine were measured. Mice received indomethacin (20 mg/kg, i.p.) to evaluate the effects of UA on indomethacin-induced enteropathy. Reactive oxygen species (ROS) on the ileal mucosa were analyzed. The fecal microbiota of HUA mice was transplanted to investigate its effect on indomethacin-induced enteropathy.

RESULTS

IMP increased luminal UA dose-dependently, with higher levels of luminal antioxidant markers. Indomethacin-induced enteropathy was significantly ameliorated in both UA-elevated groups, with decreased indomethacin-induced luminal ROS. The microbiota of HUA mice showed a significant increase in α-diversity and a significant difference in β-diversity from the control. Fecal microbiota transplantation from HUA mice ameliorated indomethacin-induced enteropathy.

CONCLUSIONS

The protective role of luminal UA in intestinal injury is likely exerted via oxidative stress elimination and microbiota composition modulation, preferably for gut immunity. Therefore, enhancing anaerobic conditions using antioxidants is a potential therapeutic target.

Molecular Mechanistic Pathways Targeted by Natural Antioxidants in the Prevention and Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) is the progressive loss of renal function and the leading cause of end-stage renal disease (ESRD). Despite optimal therapy, many patients progress to ESRD and require dialysis or transplantation. The pathogenesis of CKD involves inflammation, kidney fibrosis, and blunted renal cellular antioxidant capacity. In this review, we have focused on in vitro and in vivo experimental and clinical studies undertaken to investigate the mechanistic pathways by which these compounds exert their effects against the progression of CKD, particularly diabetic nephropathy and kidney fibrosis. The accumulated and collected data from preclinical and clinical studies revealed that these plants/bioactive compounds could activate autophagy, increase mitochondrial bioenergetics and prevent mitochondrial dysfunction, act as modulators of signaling pathways involved in inflammation, oxidative stress, and renal fibrosis. The main pathways targeted by these compounds include the canonical nuclear factor kappa B (NF-κB), canonical transforming growth factor-beta (TGF-β), autophagy, and Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid factor 2-related factor 2 (Nrf2)/antioxidant response element (ARE). This review presented an updated overview of the potential benefits of these antioxidants and new strategies to treat or reduce CKD progression, although the limitations related to the traditional formulation, lack of standardization, side effects, and safety.

The anti-hyperuricemic effect of flavonoid extract of saffron by-product and its pharmacokinetics in rats after oral administration

Only the dried stigma of the saffron, a flower deemed as the most valuable spice globally, is utilized for industrial production. Hence, there exists a growing interest in utilizing saffron floral bio-residues. The anti-hyperuricemic activity of a flavonoid extract from saffron floral bio-residues was assessed in potassium oxonate-induced hyperuricemia mice. In addition, an ultra-high performance liquid chromatography-triple quadrupole mass spectrometry method was established and validated to determine the pharmacokinetics of five main flavonoids and three phase-II metabolites in rat plasma after oral administration of the flavonoid extract for the first time. Compared with pharmacokinetic parameters of kaempferol-3-O-sophoroside, the most abundant flavonoid in the extract, and its aglycone kaempferol, we observed that coexisting compounds significantly reduced the absorption, accelerated the excretion of kaempferol-3-O-sophoroside, while significantly increasing the absorption and prolonging the residence time of kaempferol in the flavonoid extract. These results suggest the promising potential of the flavonoid extract from saffron floral bio-residues as an anti-hyperuricemic agent. Kaempferol was absorbed in plasma at high concentrations owing to the biotransformation of kaempferol glycosides in vivo.

The Prognostic Value of Serum Uric Acid in Hospitalized Patients with Acute Cerebral Infarction

Background

Previous studies reported that the level of serum uric acid (SUA) was an important risk factor for acute cerebral infarction (ACI). However, the prognostic value of SUA levels in hospitalized patients with ACI has not been fully elucidated. The aim of this study was to investigate whether the SUA level on admission was associated with subsequent mortality in hospitalized patients with ACI.

Methods

The clinical data of ACI patients obtained from December 2017 to December 2019 were retrospectively reviewed. χ² and Kaplan–Meier methods were used to compare the clinical differences and overall survival between patients with or without hyperuricemia, respectively. Univariate and multivariate analyses were used to identify independent prognoses.

Results

In the total population, the in-hospital mortality of the hyperuricemia group was significantly higher than that of the normal uric acid group (P = 0.006). In the abnormal renal function group, the in-hospital mortality among the hyperuricemia group was significantly higher than the normal uric acid group (P = 0.002). However, there was no statistical difference of in-hospital mortality between the two groups in the normal renal function group (P = 0.321). Univariate and multivariate analyses showed that a previous history of diabetes (P = 0.018), hyperuricemia (P = 0.001), and National Institutes of Health Stroke Scale (NIHSS) score on admission (P ≤ 0.001) were independent factors for all samples. The hyperuricemia (P = 0.003) on admission were independent factors for patients with abnormal renal function.

Conclusions

In ACI patients with abnormal renal function, hyperuricemia may be associated with higher in-hospital mortality than patients with normal uric acid, and hyperuricemia may be an independent associated factor for in-hospital death in the subgroup patients.

Sonneratia apetala seed oil attenuates potassium oxonate/hypoxanthine-induced hyperuricemia and renal injury in mice

Sonneratia apetala seeds are considered as prospective nutraceuticals with a high content of unsaturated fatty acids (UFAs) which are mainly distributed in the oil. It is well-known that UFAs could exhibit urate-lowering potency and protect against renal injury, indicating that S. apetala seed oil (SSO) may possess hypouricemic and nephroprotective effects. Consequently, the present work attempted to probe into the effects and mechanisms of SSO on potassium oxonate/hypoxanthine-induced hyperuricemia and associated renal injury. The results indicated that SSO treatment prominently inhibited the increase of serum uric acid (UA), creatinine (CRE), and urea nitrogen (BUN) levels and hepatic xanthine oxidase (XOD) activity in hyperuricemia mice. Kidney indexes and histopathological lesions were also remarkably ameliorated. Additionally, SSO treatment improved the renal anti-oxidant status in hyperuricemia mice by significantly reversing the increase in ROS and MDA levels as well as the decline in SOD, CAT and GSH-Px activities. SSO dramatically downregulated the expression and secretion of pro-inflammatory factors involving MCP-1, IL-1β, IL-6, IL-18 and TNF-α elicited by hyperuricemia. Furthermore, after SSO treatment, increased protein expressions of GLUT9, URAT1 and OAT1 in the hyperuricemia mice were obviously reversed. SSO treatment enormously restored Nrf2 activation and subsequent translation of related anti-oxidative enzymes in the kidneys. TXNIP/NLRP3 inflammasome activation was also obviously suppressed by SSO. In conclusion, SSO exerted favorable hypouricemic effects owing to its dual functions of downregulating the XOD activity and modulating the expressions of renal urate transport-associated proteins, and it also could alleviate hyperuricemia-induced renal injury by restoring the Keap1-Nrf2 pathway and blocking the TXNIP/NLRP3 inflammasome activation.

Could Antioxidant Supplementation Delay Progression of Cardiovascular Disease in End-Stage Renal Disease Patients?

In end-stage renal disease patients, the leading causes of mortality are of cardiovascular (CV) origin. The underlying mechanisms are complex, given that sudden heart failure is more common than acute myocardial infarction. A contributing role of oxidative stress is postulated, which is increased even at early stages of chronic kidney disease, is gradually augmented in parallel to progression to endstage renal disease and is further accelerated by renal replacement therapy. Oxidative stress ensues when there is an imbalance between reactive pro-oxidants and physiologically occurring electron donating antioxidant defence systems. During the last decade, a close association of oxidative stress with accelerated atherosclerosis and increased risk for CV and all-cause mortality has been established. Lipid peroxidation has been identified as a trigger for endothelial dysfunction, the first step towards atherogenesis. In order to counteract the deleterious effects of free radicals and thereby ameliorate, or delay, CV disease, exogenous administration of antioxidants has been proposed. Here, we attempt to summarize existing data from studies that test antioxidants for CV protection, such as vitamins E and C, statins, omega-3 fatty acids and N-acetylcysteine.

Flacourtia indica fruit extract modulated antioxidant gene expression, prevented oxidative stress and ameliorated kidney dysfunction in isoprenaline administered rats

This study evaluated the effect of Flacourtia indica fruit extract against isoprenaline (ISO) induced renal damage in rats. This investigation showed that ISO administration in rats increased the level oxidative stress biomarkers such as malondialdehyde (MDA), nitric oxide (NO), advanced protein oxidation product (APOP) in kidneys followed by a decrease in antioxidant enzymes functions. Flacourtia indica fruit extract, which is rich in strong antioxidants, also reduced the MDA, NO and APOP level in kidney of ISO administered rats. Inflammation and necrosis was also visible in kidney section of ISO administered rats which was significantly prevented by atenolol and Flacourtia indica fruit extract. Moreover, atenolol and Flacourtia indica fruit extract also modulated the genes expressions related to inflammation and oxidative stress in kidneys. The beneficial effects could be attributed to the presence of a number of phenolic antioxidants. This study suggests that Flacourtia indica fruit extract may prevent kidney dysfunction in ISO administered rats, probably by preventing oxidative stress and inflammation.

Effects of Eucommia ulmoides extract against renal injury caused by long-term high purine diets in rats

Diets of overloaded purine-rich foods for a long time are one of the important reasons to cause renal lesions. Eucommia ulmoides is one of the traditional Chinese medicine herbs, which has been used to recover functions of the kidney. However, its mechanism remains unclear. The aim of this study was to explore the effects and protective mechanism of Eucommia ulmoides extract on renal injury caused by long-term high purine diets in rats. SD rats underwent an intragastric adenine (200 mg kg^-1 d^-1) administration for 9 weeks and were treated for 15 weeks. The results demonstrated that Eucommia ulmoides extract significantly reduced serum Cre and BUN levels in rats. H&E and Masson's trichrome stains showed notable lowering of the infiltration of inflammatory cells, the formation of fibrous tissues and collagen fibers, and improvement in the pathological morphology of kidneys. It also suppressed the protein and mRNA expressions of TGF-β1 and α-SMA and enhanced E-cadherin expression. Meanwhile, Eucommia ulmoides extract prominently inhibited the mRNA expression of Col I, Col III, Col IV, TIMP-1, and TIMP-2 and promoted expressions of MMP-1, MMP-2 and MMP-9. Through our study, it is the first time to prove that Eucommia ulmoides extract could ameliorate renal interstitial fibrosis and may involve in the regulation of the extracellular matrix (ECM) degradation enzyme (MMPs/TIMPs) system, promotion of the expression of E-cadherin, and suppression of expressions of TGF-β1 and α-SMA. The results provide a significant implication for the utilization of Eunomia Ulmoides extract as functional foods to enhance renal functions and improve renal injury caused by high purine diets.

Anti-hyperuricemic potential of stevia (Stevia rebaudiana Bertoni) residue extract in hyperuricemic mice

Hyperuricemia (HUA) is considered a potent risk factor for the development of gout, renal failure, and cardiovascular disease. The current project was designed to use stevia (Stevia rebaudiana Bertoni) byproduct, named stevia residue extract (STVRE), for the treatment of HUA. Male Kunming mice were divided into six groups: normal control, model control, positive control (allopurinol, 5 mg per kg body weight [bw]), STVRE-1 (75 mg per kg bw), STVRE-2 (150 mg per kg bw), and STVRE-3 (300 mg per kg bw). HUA was induced by the administration of potassium oxonate (100 mg per kg bw), fructose (10% w/v), and yeast extract (100 mg per kg bw) for 8 weeks. STVRE significantly (p < 0.05) decreased uric acid (UA) production and ameliorated UA excretion by interacting with urate transporters. The STVRE remarkably attenuated oxidative stress mediated by UA and downregulated inflammatory-related response markers such as COX-2, NF-κB, PGE2, IL-1β, and TNF-α. Furthermore, STVRE also reversed HUA-induced abnormalities in kidneys compared with the MC group. The results of our study suggest that STVRE has potential to attenuate hyperuricemia and renal protective effects, and may be used as a natural supplement for the possible treatment of UA-related disorders.

Strength Training Reduces Cardiac and Renal Oxidative Stress in Rats with Renovascular Hypertension

Fundamento

O treino de força tem efeitos benéficos em doenças renais, além de ajudar a melhorar a defesa antioxidante em animais saudáveis.

Objetivo

Verificar se o treino de força reduz o dano oxidativo ao coração e rim contralateral para cirurgia de indução de hipertensão renovascular, bem como avaliar as alterações na atividade das enzimas antioxidantes endógenas superóxido dismutase (SOD), catalase (CAT) e glutationa peroxidase (GPx).

Métodos

Dezoito ratos machos foram divididos em três grupos (n=6/grupo): placebo, hipertenso e hipertenso treinado. Os animais foram induzidos a hipertensão renovascular através da ligação da artéria renal esquerda. O treino de força foi iniciado quatro semanas após a indução da hipertensão renovascular, teve 12 semanas de duração e foi realizada a 70% de 1RM. Depois do período de treino, os animais foram submetidos a eutanásia e o rim esquerdo e o coração foram retirados para realizar a quantificação de peróxidos de hidrogênio, malondialdeído e grupos sulfidrílicos, que são marcadores de danos oxidativos. Além disso, foram medidas as atividades das enzimas antioxidantes superóxido dismutase, catalase e glutationa peroxidase. O nível de significância adotado foi de 5% (p < 0,05).

Resultados

Depois do treino de força, houve redução de danos oxidativos a lipídios e proteínas, como pode-se observar pela redução de peróxidos de hidrogênio e níveis sulfidrílicos totais, respectivamente. Além disso, houve um aumento nas atividades das enzimas antioxidantes superóxido dismutase, catalase e glutationa peroxidase.

Conclusão

O treino de força tem o potencial de reduzir danos oxidativos, aumentando a atividades de enzimas antioxidantes. (Arq Bras Cardiol. 2021; 116(1):4-11)

Are Nutraceuticals Beneficial in Chronic Kidney Disease?

Chronic kidney disease (CKD) is a worldwide health problem in which prevalence is constantly rising. The pathophysiology of CKD is complicated and has not been fully resolved. However, elevated oxidative stress is considered to play a vital role in the development of this disease. CKD is also thought to be an inflammatory disorder in which uremic toxins participate in the development of the inflammatory milieu. A healthy, balanced diet supports the maintenance of a good health status as it helps to reduce the risk of the development of chronic diseases, including chronic kidney disease, diabetes mellitus, and hypertension. Numerous studies have demonstrated that functional molecules and nutrients, including fatty acids and fiber as well as nutraceuticals such as curcumin, steviol glycosides, and resveratrol not only exert beneficial effects on pro-inflammatory and anti-inflammatory pathways but also on gut mucosa. Nutraceuticals have attracted great interest recently due to their potential favorable physiological effects on the human body and their safety. This review presents some nutraceuticals in which consumption could exert a beneficial impact on the development and progression of renal disease as well cardiovascular disease.

Geniposide Improves Diabetic Nephropathy by Enhancing ULK1-Mediated Autophagy and Reducing Oxidative Stress through AMPK Activation

Diabetic nephropathy (DN) is a common pathological feature in patients with diabetes and the leading cause of end-stage renal disease. Although several pharmacological agents have been developed, the management of DN remains challenging. Geniposide, a natural compound has been reported for anti-inflammatory and anti-diabetic effects; however, its role in DN remains poorly understood. This study investigated the protective effects of geniposide on DN and its underlying mechanisms. We used a C57BL/6 mouse model of DN in combination with a high-fat diet and streptozotocin after unilateral nephrectomy and treated with geniposide by oral gavage for 5 weeks. Geniposide effectively improves DN-induced renal structural and functional abnormalities by reducing albuminuria, podocyte loss, glomerular and tubular injury, renal inflammation and interstitial fibrosis. These changes induced by geniposide were associated with an increase of AMPK activity to enhance ULK1-mediated autophagy response and a decrease of AKT activity to block oxidative stress, inflammation and fibrosis in diabetic kidney. In addition, geniposide increased the activities of PKA and GSK3β, possibly modulating AMPK and AKT pathways, efficiently improving renal dysfunction and ameliorating the progression of DN. Conclusively, geniposide enhances ULK1-mediated autophagy and reduces oxidative stress, inflammation and fibrosis, suggesting geniposide as a promising treatment for DN.

Probiotics, Prebiotics and Synbiotics-A Promising Strategy in Prevention and Treatment of Cardiovascular Diseases?

Recent evidence suggests that probiotics, prebiotics and synbiotics may serve as important dietary components in the prevention (especially) and treatment of cardiovascular diseases (CVD), but the recommendations for their use are often based on brief reports and small clinical studies. This review evaluates the current literature on the correlation between CVD and probiotics, prebiotics and synbiotics. Although research on probiotics, prebiotics and synbiotics has grown exponentially in recent years, particularly regarding the effect of probiotics on CVD, their mechanisms have not been clearly defined. It has been proposed that probiotics lower cholesterol levels, and may protect against CVD, by increasing bile salt synthesis and bile acid deconjugation. Similar effects have also been observed for prebiotics and synbiotics; however, probiotics also appear to have anti-oxidative, anti-platelet and anti-inflammatory properties. Importantly, probiotics not only have demonstrated effects in vitro and in animal models, but also in humans, where supplementation with probiotics decreases the risk factors of CVD. In addition, the properties of commercial probiotics, prebiotics and synbiotics remain undetermined, and further experimental research is needed before these substances can be used in the prevention and treatment of CVD. In particular, well-designed clinical trials are required to determine the influence of probiotics on trimethylamine-N-oxide (TMAO), which is believed to be a marker of CVDs, and to clarify the long-term effects, and action, of probiotic, prebiotic and synbiotic supplementation in combination with drug therapy (for example, aspirin). However, while it cannot be unequivocally stated whether such supplementation yields benefits in the prevention and treatment of CVDs, it is important to note that clinical studies performed to date have not identified any side-effects to use.

Combined Effects of Radiofrequency Electromagnetic Fields and X-Ray in Renal Tissue and Function

PURPOSE

Biochemical and histopathological properties of renal tissues were reported to be affected by both radiofrequency electromagnetic fields (RF-EMF) and ionizing radiation. The radiation-induced changes in the kidney, including the serum levels of blood urea nitrogen (BUN) and creatinine (Cr), could lead to adverse health outcomes such as chronic kidney disease. These complications signify the importance of the research in this field. Thus, in this study, the effects of ionizing and non-ionizing radiations, as well as their combination, were assessed by evaluating the alteration in BUN, Cr, and histopathological changes in kidney tissue.

MATERIALS AND METHODS

Ninety-six male Wistar rats were randomly divided into six groups and were exposed to either 900/1800MHz (mobile phone) or 2.4 GHz RF-EMF (Wi-Fi) radiation for 14 days, 8Gy x-ray, or their combination. Sera were collected from 2 mL of rat blood, then BUN and Cr levels were determined. Also, renal samples were stained with hematoxylin and eosin and evaluated histopathologically.

RESULTS

Both BUN and Cr levels raised non-significantly after exposure to 8 Gy x-rays. Moreover, all measurements in the samples of x-ray groups were in borderline or higher than normal values. The BUN levels of control, Wi-Fi, x-ray, and Wi-Fi+x-ray groups were not significantly different. However, Cr levels in the Wi-Fi group were significantly higher than those of the controls, and BUN to Cr ratio levels were significantly lower than those of the controls. Also, tubular atrophy and vessel wall thickening were associated with these exposures.

CONCLUSION

Exposure to 900/1800MHz, 2400 MHz EMF can alter the kidney function. However, pre-exposure to 900/1800MHz EMF could modulate the acute adverse effects of lethal x-ray dose, which addresses the adaptive response in the kidney.