Uric acid and progression of chronic kidney disease

Highly accessible Fe-N-C single-atom nanozymes with enhanced oxidase-like activity for smartphone-assisted colorimetric detection of uric acid

Fe-N-C single-atom nanozymes (SANzymes), which exhibit the properties of well-defined atomic structures and carefully controlled coordination environments, have become a hot research topic in biomedical fields. Unfortunately, the lower accessibility and intrinsic activity of the FeN4 sites severely limit their enzyme-like activity. Here, a densely exposed surface FeN4 structure was constructed on layered nitrogen-doped hierarchical porous carbon support through two steps of pyrolysis strategy. Using a honeycomb porous carbon support, the Fe-N-C catalyst boasted a high specific surface area with numerous Fe anchoring sites and was equipped with efficiently accessible active FeN4 structures. The Fe edge effect could modulate the electronic structure of individual Fe atoms, thereby boosting the intrinsic oxidase-like activity of the FeN4 molecules. As a result, Fe-N-C SANzymes were efficiently able to catalyze O2 with 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate, achieving higher catalytic kinetic values than previously reported SANzymes. The colorimetric sensor using Fe-N-C SANzymes further detected uric acid (UA) with a wide detection range and a low detection limit. Then the visual sensing of the colorimetric system allowed the smartphone to identify colors by HSV patterns and obtain quantitative analysis. Moreover, the developed Fe-N-C colorimetric method showed satisfactory results in clinical samples, and proved to be a simple-operated and reliable method for detection of UA. This work not only highlights the advantages of the rationally designed edge effect of iron single atoms, but also presents the promising applicability of single-atom nanozymes in clinical diagnosis and related fields.

Anti-Hyperuricemic and Nephroprotective Effects of Hydrolysate Derived from Silkworm Pupae (Bombyx mori): In Vitro and In Vivo Study

BACKGROUND

Hyperuricemia is a prevalent metabolic disorder characterized by elevated serum uric acid (UA) levels.

METHODS

In this study, hydrolysate (SPP) derived from silkworm pupae protein was isolated and identified, demonstrating anti-hyperuricemic activity. The research aimed to investigate its anti-hyperuricemic and nephroprotective effects, along with potential mechanisms, through in vitro assays and in vivo experiments using potassium oxonate/hypoxanthine-induced hyperuricemic mice.

RESULTS

The SPP exhibited significant xanthine oxidase (XOD) inhibitory activity, with an IC50 value of 7.41 mg/mL. Furthermore, SPP administration effectively reduced serum UA, blood urea nitrogen (BUN), creatinine levels, and renal pro-inflammatory cytokines in hyperuricemic mice. Mechanistic studies revealed that the anti-hyperuricemic effects of SPP may involve XOD inhibition and the modulation of renal UA transporters, specifically upregulating organic anion transporter 1 (OAT1) and ATP-binding cassette subfamily G member 2 (ABCG2) expression. Histopathological analysis and inflammatory cytokine profiling further demonstrated that SPP alleviated renal inflammation and pathological damage.

CONCLUSIONS

These findings suggest that SPP possesses a notable urate-lowering efficacy and renal protective properties, highlighting its potential as a therapeutic agent for the management and prevention of hyperuricemia (HUA).

Identification of risk factors for renal progression in adults with IgAV: a retrospective cohort study of a single center in northwest China

OBJECTIVES

This investigation sought to examine the clinical and pathological characteristics, outcomes, and risk factors linked to the progression of renal function in adult-onset immunoglobulin A (IgA) vasculitis within a single center in northwest China.

METHODS

Data were retrospectively gathered from cases of adult-onset IgA vasculitis recorded at a tertiary hospital in northwest China, covering the period from January 2013 to August 2024. During the follow-up, clinical information was compared between patients who advanced to chronic kidney disease (CKD) stage 3 and those who did not.

RESULTS

A sum of 1082 adult-onset IgA vasculitis patients (632 men; median age of 37 years) were included. Among patients with baseline proteinuria >0.5 g/24h (43.9%), 40.7% progressed to chronic kidney disease (CKD) stage 3, while 5.1% developed end-stage renal disease (ESRD). COX regression analysis indicated that older age, renal pathological grade IV, hypertension (HTN), diabetes, hyperlipidemia, and hyperuricemia were independent risk factors for CKD stage 3 progression in individuals with adult-onset IgA vasculitis.

CONCLUSIONS

Older age and comorbidities such as hypertension and diabetes significantly increase the risk of renal progression in adult-onset IgAV. Early management of these comorbidities may mitigate the risk of CKD progression.

Associations of low-carbohydrate diets patterns with the risk of hyperuricemia: a national representative cross-sectional study in Korea

BACKGROUND

The association between low-carbohydrate diets and hyperuricemia risk, a significant risk factor for gout and cardiometabolic morbidities, remains inconclusive, partly due to differing effects of replacing carbohydrates with animal- or plant-based macronutrients. This study examined associations between low-carbohydrate diet patterns and hyperuricemia risk in 39,880 adults in the Korea National Health and Nutritional Examination Study 2016-2022.

METHODS

Diet was assessed via a 24-hour dietary recall. The overall, animal-rich, and plant-rich low-carbohydrate diet score (LCDS) was calculated based on percent energy derived from protein and fat in animal and plant food sources. Hyperuricemia was defined as serum uric acid levels > 7.0 mg/dL for men and > 6.0 mg/dL for women. Multivariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression models to estimate the risk of hyperuricemia across quintiles of LCDS.

RESULTS

A significantly greater risk of hyperuricemia was observed among individuals with higher overall LCDS (OR for quintile 5 vs. quintile 1 [Q5vs.Q1]: 1.41, 95%CI:1.22-1.63, P-trend: <0.001) and animal-rich LCDS (ORQ5vs.Q1: 1.28, 95%CI:1.12-1.47, P-trend: <0.001), but not with plant-rich LCDS (ORQ5vs.Q1: 1.00, 95%CI: 0.87-1.16). These positive associations for overall LCDS and animal-rich LCDS were evident in overweight individuals (ORQ5vsQ1: 1.53, 95%CI: 1.29-1.82 for overall LCDS; and 1.39, 95%CI: 1.19-1.63 for animal-rich LCDS; all P-trends < 0.001), but not in non-overweight individuals (all P-interactions: <0.001).

CONCLUSIONS

In our study, animal-based low-carbohydrate diets were associated with a greater risk of hyperuricemia, while no association was observed for plant-based low-carbohydrate diets. Larger cohort studies are warranted to replicate these findings.

Overview of pharmacodynamical research of traditional Chinese medicine on hyperuricemic nephropathy: from the perspective of dual-regulatory effect on the intestines and kidneys

Uncontrolled hyperuricemia contributes to chronic kidney disease, characterized by renal inflammatory cell infiltration and tubulointerstitial fibrosis, eventually leading to renal failure. In addition to liver and kidney, the intestine tract plays a vital role in the development and progression of hyperuricemia and hyperuricemic nephropathy (HN) through various mechanisms. The conventional therapeutic strategy for HN is uric acid-lowering therapy (ULT) and renal protection; however, unsatisfactory results are often obtained in clinical practice. Growing evidence has demonstrated that traditional Chinese medicines (TCMs) achieve an anti-HN effect by modulating multiple targets and approaches with fewer side effects. Therefore, this paper reviews the pathogenesis of HN, including the role of soluble and insoluble urates in kidney and intestine, and the role of intestinal tract in the progression of HN. Meanwhile, the recent advancements in TCMs for the treatment of HN are summarized and analyzed, with a focus on their modulation of intestinal flora and metabolites, urate-related transporters, immuno-inflammation and barrier function in the intestines. Notably, for the first time, we propose the perspective that TCMs treat HN through a dual-regulatory effect on the intestines and kidneys. Additionally, the problems existing in current research and the feasible research strategies combined with emerging technologies such as fermentation and nanotechnology are discussed, thus providing novel ideas for HN management.

A comparative metabolomic analysis reveals the metabolic variations among cartilage of Kashin-Beck disease and osteoarthritis

Aims

The metabolic variations between the cartilage of osteoarthritis (OA) and Kashin-Beck disease (KBD) remain largely unknown. Our study aimed to address this by conducting a comparative analysis of the metabolic profiles present in the cartilage of KBD and OA.

Methods

Cartilage samples from patients with KBD (n = 10) and patients with OA (n = 10) were collected during total knee arthroplasty surgery. An untargeted metabolomics approach using liquid chromatography coupled with mass spectrometry (LC-MS) was conducted to investigate the metabolomics profiles of KBD and OA. LC-MS raw data files were converted into mzXML format and then processed by the XCMS, CAMERA, and metaX toolbox implemented with R software. The online Kyoto Encyclopedia of Genes and Genomes (KEGG) database was used to annotate the metabolites by matching the exact molecular mass data of samples with those from the database.

Results

A total of 807 ion features were identified for KBD and OA, including 577 positive (240 for upregulated and 337 for downregulated) and 230 negative (107 for upregulated and 123 for downregulated) ions. After annotation, LC-MS identified significant expressions of ten upregulated and eight downregulated second-level metabolites, and 183 upregulated and 162 downregulated first-level metabolites between KBD and OA. We identified differentially expressed second-level metabolites that are highly associated with cartilage damage, including dimethyl sulfoxide, uric acid, and betaine. These metabolites exist in sulphur metabolism, purine metabolism, and glycine, serine, and threonine metabolism.

Conclusion

This comprehensive comparative analysis of metabolism in OA and KBD cartilage provides new evidence of differences in the pathogenetic mechanisms underlying cartilage damage in these two conditions.

Association of time-averaged serum uric acid level with clinicopathological information and long-term outcomes in patients with IgA nephropathy

Objective

Whether serum uric acid (SUA) at baseline could been identiûed as a risk factor for progression in IgA nephropathy (IgAN) patients remains unclear, therefore, long- term SUA control levels must be monitored. We aimed to investigate the relevant factors affecting time-averaged SUA (TA-SUA) and to assess the prognostic value of TA-SUA in IgAN.

Methods

This retrospective study included 152 patients with IgAN. The relationships between TA-SUA and clinicopathological features and renal outcomes (defined as the doubling of the baseline serum creatinine level or end-stage renal disease) were analyzed in groups divided by quartiles of TA-SUA levels, the presence of hyperuricemia, and sex.

Results

Patients with high TA-SUA levels had higher levels of baseline SUA, blood urea nitrogen (BUN), triglycerides, serum C3 and serum C4 and were more likely to be male and have hypertension, proteinuria, poor renal function, and pathological injuries including high grades of tubular atrophy/interstitial fibrosis (T1-T2). These patients had a poorer prognosis compared with patients with low TA-SUA levels. The TA-SUA level was positively correlated with baseline age and BUN, triglycerides, serum C3, and serum C4 levels, and negatively correlated with baseline eGFR. Survival curve analysis indicated that persistent hyperuricemia was associated with significantly poorer renal outcomes than normo-uricemia in both men and women. The TA-SUA level also was an independent predictor of renal outcome in patients with IgAN, with optimal cutoû values of 451.38 µmol/L (area under the curve (AUC) = 0.934) for men and 492.83 µmol/L (AUC = 0.768) for women.

Conclusions

The TA-SUA level is associated with triglyceride level, complement component levels, renal function, and pathological severity of IgAN, and it may be a prognostic indicator in male and female patients with IgAN.

Risk stratification for worsening renal function and renal decline in heart failure patients with reduced ejection fraction after sacubitril/valsartan treatment

BACKGROUND

In the real-world setting, data regarding renal decline following sacubitril/valsartan treatment are lacking. This study aimed to develop a scoring system to predict renal outcome in sacubitril/valsartan-treated patients.

METHODS

Between 2017 and 2018, a total of 1505 heart failure patients with reduced ejection fraction (HFrEF) undergoing sacubitril/valsartan treatment were consecutively enrolled from 10 hospitals to serve as the derivation cohort. Another 1620 HFrEF patients receiving sacubitril/valsartan were included as the validation cohort. Worsening renal function (WRF) was defined as a serum creatinine increase of >0.3 mg/dL and/or >25 % at 8 months of sacubitril/valsartan treatment. The derivation cohort was used to identify independent predictive factors for WRF through multivariate analysis, which were then used to develop the risk score system.

RESULTS

Among the 3125 HFrEF patients, 689 (22.0 %) patients had WRF at 8 months following sacubitril/valsartan treatment. In the derivation cohort, six prognostic factors (age, functional class, history of peripheral arterial disease, diabetes mellitus, gout or hyperuricemia, and serum albumin level) were independently associated with WRF, and were combined into a risk predicting score. This score showed accurate discrimination in the derivation and validation cohorts (Harrell's concordance indexes 0.74 and 0.71, 95 % confidence intervals 0.71-0.78 and 0.69-0.74, respectively). Patients with a higher risk score experienced a more rapid decline in renal function, poorer clinical outcomes, and a higher rate of discontinuation of sacubitril/valsartan treatment.

CONCLUSIONS

This study developed a score for WRF after sacubitril/valsartan treatment, which may assist clinicians with risk stratification and therapeutic decision-making.

Role of hypertension in progression of pediatric CKD

Hypertension is frequent in children with chronic kidney disease (CKD). Its prevalence varies according to CKD stage and cause. It is relatively uncommon in children with congenital kidney disease, while acquired kidney disease is associated with a higher prevalence of hypertension. Studies in children with CKD utilizing ambulatory blood pressure monitoring also showed a high prevalence of masked hypertension. Uncontrolled and longstanding hypertension in children is associated with progression of CKD. Aggressive treatment of high blood pressure should be an essential part of care to delay CKD progression in children.

Association between multiple metal(loid)s exposure and renal function: a cross-sectional study from southeastern China

In the real world, humans are exposed to multiple metal(loid)s (designated hereafter metals) that contain essential metals as well as toxic metals. Exposure to the metal mixture was assumed to be associated with renal function impairment; however, there is no consensus on available studies. Therefore, we here explored the association between multiple metals exposure and indicators of renal function in the general population from southeastern China. A total of 11 metals with 6 human essential metals and 5 toxic metals were determined in the selected 720 subjects. In addition, serum uric acid (SUA), serum creatinine (SCR), and the estimated glomerular filtration rate (eGFR) were measured or calculated as indicators of renal function. Using multiple flexible statistical models of generalized linear model, elastic net regression, and Bayesian kernel machine regression, the joint as well as the individual effect of metals within the mixture, and the interactions between metals were explored. When exposed to the metal mixture, the statistically non-significantly increased SUA, the significantly increased SCR, and the significantly declined eGFR were observed. In addition, the declined renal function may be primarily attributed to lead (Pb), arsenic (As), and nickel (Ni) exposure. Finally, interactions, such as the synergistic effect between Pb and Mo on SUA, whereas the antagonistic effect between Ni and Cd on SCR and eGFR were identified. Our finding suggests that combined exposure to multiple metals would impair renal function. Therefore, reducing exposure to toxic heavy metals of Pb, As, and Cd and limiting exposure to the human essential metal of Ni would protect renal function.

The association between serum uric acid and creatine phosphokinase in the general population: NHANES 2015-2018

BACKGROUND

The association between serum creatine phosphokinase (CPK), a standard biochemical measure of acute myocardial infarction, and serum uric acid (sUA) has not been studied. This study aimed to determine the association between sUA and CPK in the general population of the US.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES) 2015-2018 were used, including a total of 8,431 subjects aged ≥ 30 years. Weighted multiple regression analysis was used to estimate the independent relationship between sUA and CPK. Fitted smoothing curves and weighted generalized additive models were also performed.

RESULTS

We found a positive relationship between sUA and CPK after adjusting for potential confounders. In subgroup analyses stratified by sex and race/ethnicity, sUA was positively correlated with CPK in each subgroup. The association between sUA and CPK followed an inverted U-shaped curve in females (turning point: sUA = 428.3 μmol/L).

CONCLUSIONS

Our study suggested that sUA level was positively correlated with CPK in the general population of the US. However, CPK increased with sUA until the turning point (sUA = 428.3 μmol/L) in females. Fundamental research and large sample prospective studies are needed to determine the exact mechanism of the association between sUA and CPK.

Association of uric acid with the decline in estimated glomerular filtration rate in middle-aged and elderly populations: evidence based on the China Health and Retirement Longitudinal Study

OBJECTIVE

Whether uric acid (UA) has an effect on renal function remains controversial. We aimed to investigate the association between serum UA with the decline in estimated glomerular filtration rate (eGFR) in middle-aged and elderly populations in the China Health and Retirement Longitudinal Study (CHARLS).

DESIGN

Longitudinal cohort study.

SETTING

This was a second analysis of a public dataset (CHARLS).

PARTICIPANTS

In this study, 4538 middle-aged and elderly individuals were screened after removing individuals younger than 45 years old, with kidney disease, malignant tumour and missing values.

OUTCOME MEASURES

Blood tests were performed both in 2011 and 2015. Decline in eGFR was defined as an eGFR decrease of more than 25% or deterioration of the eGFR stage during the 4-year follow-up period. Logistic models corrected for multiple covariables were used to analyse the association of UA with the decline in eGFR.

RESULTS

The median (IQR) concentrations of serum UA grouped by quartiles were 3.1 (0.6), 3.9 (0.3), 4.6 (0.4) and 5.7 (1.0) mg/dL, respectively. After multivariable adjustment, the OR of the decline in eGFR was higher for quartile 2 (3.5-<4.2 mg/dL: OR 1.44; 95% CI 1.07 to 1.64; p<0.01), quartile 3 (4.2-<5.0 mg/dL: OR 1.72; 95% CI 1.36 to 2.18; p<0.001) and quartile 4 (≥5.0 mg/dL: OR 2.04; 95% CI 1.58 to 2.63; p<0.001) when compared with quartile 1 (<3.5 mg/dL), and the p value for the trend was <0.001.

CONCLUSIONS

Over a 4-year follow-up period, we found that elevated UA was associated with a decline in eGFR in the middle-aged and elderly individuals with normal renal function.

The Use of Thiazide Diuretics for the Treatment of Hypertension in Patients With Advanced Chronic Kidney Disease

The use of thiazide diuretics for the treatment of hypertension in patients with advance chronic kidney disease. Thiazides have been recommended as the first-line for the treatment of hypertension, yet their use has been discouraged in advanced chronic kidney disease (CKD), as they are suggested to be ineffective in advanced CKD. Recent data suggest that thiazide diuretics may be beneficial blood pressure control in addition to natriuresis in existing CKD. This review discusses the commercially available thiazides with a focus on thiazide pharmacology, most common adverse effects, clinical uses of thiazide diuretic, and the evidence for efficacy of thiazide use in advanced CKD.

Does uric acid-lowering treatment slow the progression of chronic kidney disease? A meta-analysis of randomized controlled trials

INTRODUCTION

Hyperuricemia has been proposed as an independent factor in the development and progression of chronic kidney disease (CKD). However, the effect of uric acid-lowering therapies on delaying CKD progression is still uncertain. Therefore, this systemic review aims to assess the effect of uric acid-lowering therapies on renal outcomes in pre-dialysis CKD patients.

METHODS

PubMed, Cochrane Library, and Lilacs databases were searched until April 24, 2021, for randomized clinical trials of CKD patients on uric acid-lowering treatment with xanthine-oxidase (XO) inhibitors. The weighted mean difference (WMD) or standard mean difference (SMD) with confidence interval (CI) were pooled using a random-effects model.

RESULTS

Among 567 studies found, eighteen met the inclusion criteria (n=2463 participants). Compared to the patient's control group, the WMD for the glomerular filtration ratio (GFR) and serum creatinine changes of the treated group was 2.02ml/min/1.73m² (95%CI 0.41 to 3.63, P=0.014) and -0.19mg/dl (95%CI -0.34 to -0.04, I²=86.2%, P=0.011), respectively. Subgroup analyses showed that the difference in follow-up time and CKD population type in the studies may explain the controversy about the role of uric acid-lowering therapies in CKD progression. The GFR and creatinine outcomes analysis by types of XO inhibitors showed no difference between the control and treated groups. Uric acid-lowering therapies were strongly associated with decreased serum uric acid and urinary protein-creatinine ratio and urinary albumin-creatinine ratio.

CONCLUSIONS

These findings suggest that uric acid-lowering treatment may slow CKD progress and reduce protein and albumin excretion. However, larger and properly powered randomized clinical trials with specific CKD populations are needed to confirm these findings.

Hyperuricemia: an unrecognized risk factor for kidney-related sequelae in children with hemolytic uremic syndrome

BACKGROUND

Chronic kidney-related sequelae after STEC-HUS occur in 20-40% of patients. Hyperuricemia (HU) may cause acute and chronic toxicity involving the kidneys. We retrospectively assessed if there was an association between the presence of HU during the acute illness and that of kidney-related sequelae in children with STEC-HUS.

METHODS

Children with STEC-HUS who had clinical and laboratory data at 2 years of follow-up were included in this case-control study. Univariate and multivariate analyses were performed between patients with (cases) or without (controls) kidney-related sequelae to identify factors associated with outcomes, including different measures of serum uric acid (sUA) (baseline level, peak, and duration of HU). HU was defined as sUA > 8 mg/dL.

RESULTS

Of 86 patients included, 77.9% had HU. Patients with sequelae (n = 41) had a higher prevalence of HU (41/41 vs. 26/45, p < 0.01), higher baseline leukocyte count, serum creatinine (sCr), and sUA levels as well as lower sodium than controls. During hospitalization, cases also had higher sCr peak, sUA peak and duration of HU, requirement and duration of dialysis, extrarenal complications, and hypertension. By multivariate analysis, after adjusting for length of dialysis, only duration of HU (p = 0.0005; OR 1.7, 95% CI 1.27-2.36) remained as an independent predictor of sequelae, with a best cutoff of 5.5 days (AUC 0.95, specificity 80%, sensitivity 100%).

CONCLUSIONS

The presence of HU is a common finding in children with STEC-HUS and its duration during the acute stage was associated with kidney-related sequelae, regardless of the duration of dialysis. A higher resolution version of the Graphical abstract is available as Supplementary Information.

Hypercaloric Diet Promotes Metabolic Disorders and Impaired Kidney Function

Poor dietary habits such as overconsumption of hypercaloric diets characterized by a high content of fructose and fat are related to metabolic abnormalities development such as obesity, diabetes, and dyslipidemia. Accumulating evidence supports the hypothesis that if energy intake gradually exceeds the body's ability to store fat in adipose tissue, the prolonged metabolic imbalance of circulating lipids from endogenous and exogenous sources leads to ectopic fat distribution in the peripheral organs, especially in the heart, liver, and kidney. The kidney is easily affected by dyslipidemia, which induces lipid accumulation and reflects an imbalance between fatty acid supply and fatty acid utilization. This derives from tissue lipotoxicity, oxidative stress, fibrosis, and inflammation, resulting in structural and functional changes that lead to glomerular and tubule-interstitial damage. Some authors indicate that a lipid-lowering pharmacological approach combined with a substantial lifestyle change should be considered to treat chronic kidney disease (CKD). Also, the new therapeutic target identification and the development of new drugs targeting metabolic pathways involved with kidney lipotoxicity could constitute an additional alternative to combat the complex mechanisms involved in impaired kidney function. In this review article, we first provide the pathophysiological evidence regarding the impact of hypercaloric diets, such as high-fat diets and high-fructose diets, on the development of metabolic disorders associated with impaired renal function and the molecular mechanisms underlying tissue lipid deposition. In addition, we present the current progress regarding translational strategies to prevent and/or treat kidney injury related to the consumption of hypercaloric diets.

TMEM16F mediated phosphatidylserine exposure and microparticle release on erythrocyte contribute to hypercoagulable state in hyperuricemia

The link between hyperuricemia (HUA) and the risk of venous thromboembolism (VTE) has been well established. However, the mechanisms of thrombus generation and the effect of HUA on procoagulant activity (PCA) of erythrocytes remain unclear no matter in uremia or hyperuricemia. Here, phosphatidylserine (PS) exposure, microparticles (MPs) release, cytosolic Ca2+, TMEM16F expression, reactive oxygen species (ROS) and lipid peroxidation of erythrocyte were detected by flow cytometer. PCA was assessed by coagulation time, purified coagulation complex and fibrin production assays. The fibrin formation was observed by scanning electron microscopy (SEM). We found that PS exposure, MPs generation, TMEM16F expression and consequent PCA of erythrocyte in HUA patients significantly increased compared to those in healthy volunteers. Furthermore, high UA induced PS exposure, and MPs release of erythrocyte in concentration and time-dependent manners in vitro, which enhanced the PCA of erythrocyte and was inhibited by lactadherin, a PS inhibitor. Additionally, using SEM, we also observed compact fibrin clots with highly-branched networks and thin fibers supported by red blood cells (RBCs) and RBC-derived MPs (RMPs). Importantly, we demonstrated UA enhanced the production of ROS and lipid peroxidation and reduced the generation of glutathione (GSH) of erythrocyte, which enhanced TMEM16F activity and followed PS externalization and RMPs formation. Collectively, these results suggest that Ca2+-dependent TMEM16F activation may be responsible for UA-induced PS exposure and MPs release of RBC, which thereby contribute to the prothrombotic risk in HUA.

An evaluation of the roles of hematuria and uric acid in defining the prognosis of patients with IgA nephropathy

In recent years, many significant advances have been made in determining which clinical manifestations and pathologic lesions can provide prognostic information for patients with IgA nephropathy (IgAN). However, some important questions remain, including the long-term consequences of hematuria, both macroscopic (MH) and microscopic (mH), in patients with IgAN. The importance of distinguishing patients who have a single episode of MH of long duration from those with recurrent episodes of short duration and the prognostic importance of the episodes of acute kidney injury (AKI) that sometimes accompany episodic MH will be discussed. Studies that have evaluated the mechanisms that may be responsible for recurrent MH and the toxic effects of red blood cells (RBCs), or their constituents, on kidney tubules will also be addressed. In the last section, I will review the evidence that hyperuricemia (HU) may be a significant independent risk factor for progressive kidney disease in patients with IgAN.

The Effects of Febuxostat on Urine NGAL and Urine KIM-1 in Patients with Hyperuricemia

Retrospective analysis of the effects of febuxostat on urine neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in patients with hyperuricemia was performed. From January 2018 to June 2018, there were 45 patients with asymptomatic hyperuricemia in the outpatient or inpatient of Changzhou Second People's Hospital, which were divided into the febuxostat group (25 cases) and the control group (20 cases). We collected the patients' baseline indicators and testing indicators after three months of treatment, including blood urea nitrogen, blood creatinine, blood uric acid, urine microalbumin, urine NGAL, urine KIM-1, and other indicators. The subjects in both groups were given lifestyle intervention, instructed to drink more water, and given a low-purine diet. The patients in the febuxostat group took febuxostat 40 mg/D or 80 mg/D. We used SPSS 25.0 statistical software for statistical analysis. Baseline indexes between the febuxostat group and the control group and indexes after treatment between two groups were both performed by independent sample t-test, and paired t-test was used for self-comparison between the groups before and after treatment. There was no significant difference in age, sex, body mass index (BMI), urea nitrogen, creatinine, uric acid, urine microalbumin/creatinine, urine NGAL/creatinine, and urine KIM-1/creatinine between the two groups before treatment (P > 0.05). Compared with before treatment, after 3 months of intervention, the levels of serum uric acid, urine microalbumin/creatinine, urine NGAL/creatinine, and urine KIM-1/creatinine were significantly decreased in the febuxostat group (P < 0.05), while the changes of blood urea nitrogen, serum creatinine, and epidermal growth factor receptor (eGFR) were not statistically significant (P > 0.05). After 3 months of intervention, the control group had no significant changes in blood urea nitrogen, creatinine, eGFR, uric acid, microalbumin/creatinine, urine NGAL/creatinine, and urine KIM-1/creatinine (P > 0.05). After 3 months of intervention, compared with the control group, the serum uric acid, microalbumin/creatinine, urine NGAL/creatinine, and urine KIM-1/creatinine were significantly decreased in the febuxostat group (P < 0.05), but there was no significant difference in blood urea nitrogen, creatinine, and eGFR (P > 0.05). Febuxostat can reduce urine NGAL/creatinine and urine KIM-1/creatinine levels in patients with hyperuricemia and has the protective effects on renal tubular injury caused by hyperuricemia, which can provide evidences for the early prevention and treatment of asymptomatic hyperuricemia.

Effect Modification of Hyperuricemia, Cardiovascular Risk, and Age on Chronic Kidney Disease in China: A Cross-Sectional Study Based on the China Health and Nutrition Survey Cohort

Introduction

The question of whether the increased burden of chronic kidney disease (CKD) is caused by the interaction of hyperuricemia and cardiovascular disease (CVD) risk factors or is accelerated by aging remains unresolved. The purpose of this study is to better understand the effect modification of hyperuricemia, cardiovascular risk, and age on CKD among the Chinese population.

Methods

This cross-sectional study of 8243 participants was derived from the China Health and Nutrition Survey (CHNS) in 2009. Inclusion criteria included age ≥18 years, non-pregnancy, and no history of high-protein diet prior to blood test. Demographics, comorbidities, health-related behaviors, and serum biomarkers were collected. Interaction association of hyperuricemia, CVD risk and age with CKD were analyzed using Logistic regression.

Results

CKD was detected in 359 (27.2%, 95% CI 24.8∼29.7%) of 1321 participants with hyperuricemia and 680 (9.8%, 95% CI 9.1∼10.5%) of 6,922 participants without hyperuricemia, and these patterns remained significant after controlling for age, gender, and Framingham risk score (adjusted odds ratio [aOR] 3.82, 95% CI 3.20∼4.57). We found a negative multiplicative interaction between hyperuricemia and CVD risk on CKD. The aOR in low-CVD risk groups was 5.51 (95% CI 4.03∼7.52), followed by medium-CVD risk groups (aOR: 3.64, 95% CI 2.61∼5.09) and high-CVD risk groups (aOR: 2.89, 95% CI 2.12∼3.96). CVD risk was less associated with CKD in hyperuricemia group (aOR: 0.92, 95% CI 0.68∼1.22) than in non-hyperuricemia group (aOR: 1.43, 95% CI 1.21∼1.70). Furthermore, hyperuricemia and age had a significant additive effect on CKD, with a synergy index of 2.26 (95% CI 1.45∼3.52). Coexisting with older age and hyperuricemia, the likelihood of developing CKD was higher than the sum of the two alone.

Conclusion

The link between hyperuricemia and CKD begins at a young age and becomes stronger in the low CVD risk group. For young adults, early detection of hyperuricemia, routine CVD risk assessment, and timely intervention of modifiable factors are warranted.

Effect of Bempedoic Acid on atherogenic lipids and inflammation: A meta-analysis

BACKGROUND

Bempedoic acid is a novel non-statin drug that was developed to treat hyperlipidemia in combination with other lipid-lowering drugs in those patients who need additional lipid lowering.

OBJECTIVES

(1) To investigate the lipid efficacy of bempedoic acid; (2) to analyze the anti-inflammatory effects of bempedoic acid estimated through high sensitivity C-reactive protein (hsCRP).

METHODS

We performed a meta-analysis including randomized trials of bempedoic acid therapy, reporting low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), apolipoprotein B and hsCRP with a minimum of 4 weeks of follow-up. The primary endpoint was defined as the percentage change in lipids and hsCRP levels measured from baseline to follow-up, comparing groups of subjects on bempedoic acid versus placebo.

RESULTS

Seven eligible trials of bempedoic acid (3892 patients) were included. The bempedoic acid therapy was associated with a significant reduction in LDL-C levels [-20.3% (CI 95% -23.5 to -17.1)]; I²=43%]. Similarly, a significant percentage reduction in the apolipoprotein B levels [-14.3% (CI 95% -16.4 to -12.1)]; p<0.05; I²=46%], non-HDL-C levels [-15.5% (CI 95% -18.1 to -13.0)]; p<0.05; I²=53%] and hsCRP [-23.4% (CI 95% -32.6 to -14.2)]; p<0.05; I²=69%] was demonstrated with the bempedoic acid use. The sensitivity analysis showed that the results were robust.

CONCLUSION

Our data suggests that the use of bempedoic acid significantly reduces the levels of all atherogenic lipid markers, including LDL-C, non-HDL-C and apolipoprotein B. Furthermore, considering hsCRP levels, the drug produces an anti-inflammatory effect.

Hyperuricemia and hypertriglyceridemia indicate tubular atrophy/interstitial fibrosis in patients with IgA nephropathy and membranous nephropathy

PURPOSE

Hyperuricemia (HUA) and hypertriglyceridemia (HTG) were very common in chronic kidney disease (CKD) and associated with accelerated progression of CKD. This was a retrospective, cross-sectional study which aimed to explore the relationship between serum uric acid levels or triglyceride levels and tubular atrophy/interstitial fibrosis (proven by renal biopsy).

METHODS

The present study enrolled 229 CKD individuals who included 127 biopsy-proven primary IgA nephrology (IgAN) patients and 102 biopsy-proven primary membranous nephropathy (MN) patients. The baseline characteristics at the time of the kidney biopsy were collected. According to the serum uric acid (UA) or triglyceride (TG) whether it exceeds the normal reference range, patients were divided into non-HUA (n = 127), HUA (n = 102), non-HTG (n = 119), and HTG group (n = 110). Based on the extent of tubular atrophy/interstitial fibrosis, patients were divided into no/mild injury (T0, n = 127), moderate injury (T1, n = 102). Multivariable logistic regression for factors predicting moderate tubular atrophy/interstitial fibrosis was performed.

RESULTS

There were 127 IgAN and 102 MN cases among 229 patients in the present study. The prevalence of HUA was 44.5% (n = 102), 40.9% (n = 52), and 49.0% (n = 50) in all patients, IgAN patients and MN patients, respectively (P = 1.49). The prevalence of HTG was 48.0% (n = 110), 29.9% (n = 38), and 70.6% (n = 72) (P < 0.001), respectively, as well. Multivariate logistic regression analysis showed that HUA and HTG were independent risk factors for moderate tubular atrophy/interstitial fibrosis (HUA OR = 2.335, 95% CI = 1.147-4.755, P = 0.019; HTG OR = 2.646, 95% CI = 1.289-5.432, P = 0.008). The area under curve (AUC) of model 1 (HUA + eGFR + HTG + age + serum globulin + 24 h urinary protein, AUC = 0.876) was larger than the other two models; however, there was no significant difference among these models (all P > 0.05).

CONCLUSIONS

Hyperuricemia and hypertriglyceridemia, which were prevalent in CKD patients, were the independent risk factors for moderate tubular atrophy/interstitial fibrosis. HUA together with HTG could improve the value of diagnosis for moderate tubular atrophy/interstitial fibrosis to some extent.

Purification, identification, and computational analysis of xanthine oxidase inhibitory peptides from kidney bean

Hyperuricemia is related to plenty of diseases, seriously damaging human health. Current clinical drugs used to treat hyperuricemia have many adverse effects. In this study, kidney bean hydrolysate (KBH) was found to exert high xanthine oxidase inhibitory (XOI) activity. Compared to KBH (50.31 ± 2.73%), XOI activities of three fractions (M_w <5 kDa, M_w <3 kDa, M_w  < 1 kDa) by ultrafiltration were higher and increased to 58.58 ± 3.57%, 59.34 ± 1.78%, and 55.05 ± 5.00%, respectively (P < 0.05). A total of 69 peptides were identified by HPLC-ESI-MS/MS and analyzed binding affinities with XO with the help of molecular docking. AVDSLVPIGR, DWYDIK, LDNLLR, ISPIPVLK, ISSLEMTR showed well binding affinities with XO and DWYDIK presented the highest XOI activity (68.63 ± 5.07%) among five synthetic peptides (P < 0.05). Additionally, visual analysis results indicated that DWYDIK was pushed into the hydrophobic channel and formed hydrogen bonds with pivotal amino acids of xanthine oxidase. Overall, KBH could be a promising candidate as anti- hyperuricemia functional food. PRACTICAL APPLICATION: This research initially revealed that kidney bean peptides could significantly inhibit the activity of xanthine oxidase, indicating kidney bean peptides could be a treatment for hyperuricemia. Kidney bean peptides may have commercial potentials as a safer alternative with few side effects to drugs.

[Association between serum uric acid and subclinical cardiac damage in children with primary hypertension]

OBJECTIVE

To evaluate the condition of subclinical cardiac damage in children with primary hypertension and the association between serum uric acid and subclinical cardiac damage.

METHODS

A retrospective analysis was performed on the medical data of 55 children who were hospitalized and diagnosed with primary hypertension in the Department of Cardiology, Children's Hospital of Soochow University from January 2015 to June 2020. Forty-five healthy children, matched for age and sex, were enrolled as the control group. The two groups were compared in terms of clinical features, laboratory examination, and parameters for left ventricular structure, systolic function, and diastolic function. The correlation of serum uric acid with the parameters for left ventricular structure, systolic function, and diastolic function in children with primary hypertension was analyzed.

RESULTS

Compared with the control group, the hypertension group had significantly higher left ventricular mass (LVM), left ventricular mass index (LVMI), and relative wall thickness (RWT) (P < 0.05). Among the children with primary hypertension, 20 (36%) had left ventricular hypertrophy. The hypertension group had significantly larger left atrial diameter and aortic root diameter than the control group (P < 0.05). The hypertension group had a significantly higher ratio of early diastolic mitral inflow velocity to early diastolic mitral annular velocity than the control group (P < 0.05). The correlation analysis showed that in children with primary hypertension, serum uric acid was positively correlated with LVM (r=0.534, P < 0.01), left atrial diameter (r=0.459, P < 0.01), and aortic root diameter (r=0.361, P=0.010). After adjustment for blood pressure, serum uric acid was still positively correlated with the above parameters (P < 0.05).

CONCLUSIONS

Children with primary hypertension may have subclinical cardiac damage such as left ventricular hypertrophy, left ventricular diastolic dysfunction, left atrial enlargement, and proximal aortic dilation. Elevated serum uric acid is significantly associated with cardiac damage in children with primary hypertension.

Association between relative fat mass, uric acid, and insulin resistance in children with chronic kidney disease

INTRODUCTION

This cross-sectional study investigates the association between insulin resistance (IR) and serum uric acid (sUA) and relative fat (RFM) and lean mass (RLM) profiles in children with chronic kidney disease (CKD).

MATERIAL AND METHODS

RLM and RFM were assessed by bioimpedance spectroscopy in 41 children and adolescents. Normal weight obesity (NWO) was defined as normal height-age body mass index and RFM >85th percentile, according to age and sex. Homeostatic model assessment of insulin resistance (HOMA-IR) level >95th percentile, according to sex and pubertal stage, and sUA >7 mg/dl were used to define IR and hyperuricemia, respectively.

RESULTS

High RFM (15 patients) and NWO (7 patients) were associated with higher HOMA-IR in total (p < 0.001) and normal-weight patients (p = 0.004), respectively. RFM was positively and RLM negatively correlated to HOMA-IR (rs = 0.500, p = 0.001 and rs = -0.539, p < 0.001, respectively) and sUA (rs = 0.370, p = 0.017 and rs = -0.325, p = 0.038, respectively), while sUA was positively correlated to HOMA-IR (rs = 0.337, p = 0.031). Hyperuricemia (16 patients) was positively associated with higher RFM and HOMA-IR (p = 0.001 and p = 0.010, respectively). The correlation between sUA and HOMA-IR lost significance after adjustment for RFM. In logistic regression analysis, a 5% increase in RFM was associated with IR (11 patients) independently of the age, sex, sUA, and CKD stage in both total (OR 2.174, 95% CI 1.115-4.225) and normal-weight (OR 3.504, 95% CI 1.110-11.123) patients.

CONCLUSION

Children with high RFM, including those presenting NWO, are at risk for IR regardless of CKD stage. RFM is probably the mediator of the link between sUA and IR.

Molecular Pathophysiology of Uric Acid Homeostasis

Uric acid, the end product of purine metabolism, plays a key role in the pathogenesis of gout and other disease processes. The circulating serum uric acid concentration is governed by the relative balance of hepatic production, intestinal secretion, and renal tubular reabsorption and secretion. An elegant synergy between genome-wide association studies and transport physiology has led to the identification and characterization of the major transporters involved with urate reabsorption and secretion, in both kidney and intestine. This development, combined with continued analysis of population-level genetic data, has yielded an increasingly refined mechanistic understanding of uric acid homeostasis as well as greater understanding of the genetic and acquired influences on serum uric acid concentration. The continued delineation of novel and established regulatory pathways that regulate uric acid homeostasis promises to lead to a more complete understanding of uric acid-associated diseases and to identify new targets for treatment.