Hyperuricemia, the kidneys, and the spectrum of associated diseases: a narrative review

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.

Skipjack Tuna (Katsuwonus pelamis) Dark Muscle Hydrolysate Ameliorates Hyperuricemia in Mice via Regulating Gut Microbiota and Serum Metabolism

Peptides have emerged as promising agents for ameliorating hyperuricemia (HUA), a condition that poses significant risks to human health. This study evaluated the HUA-alleviating potential of skipjack tuna dark muscle hydrolysate (STDH) in a mouse model of HUA induced by potassium oxonate (PO) and hypoxanthine (Hx). The results demonstrated elevated serum uric acid (SUA) levels, increased xanthine oxidase (XOD) activity in the serum and liver, and kidney and intestinal damage in HUA mice. Although the standard drug allopurinol (AP) effectively reduced SUA levels and lowered XOD activity in the serum and liver, it exacerbated kidney damage and caused significant weight loss. In contrast, STDH intervention not only significantly lowered SUA, serum creatinine (SCr), and blood urea nitrogen (BUN) levels but also inhibited XOD activity in serum and liver. Notably, STDH ameliorated renal and intestinal morphological damage, as evidenced by hematoxylin-eosin (HE) staining. Gut microbiome analysis further revealed that STDH normalized the HUA-associated elevation of the Bacteroidetes/Firmicutes ratio. Untargeted metabolomics identified STDH's regulatory effects on glycine, serine, and threonine metabolism; arginine and proline metabolism; and glycerophospholipid metabolism, with glutamine implicated as a key player in HUA pathogenesis. These findings demonstrate that STDH effectively alleviates HUA while avoiding adverse effects associated with conventional therapy, positioning it as a safe and cost-effective functional food candidate for HUA management.

Isolation and Characterization of Highly Active Uricase from Alcaligenes spp. Strain UR1

For the first time, this study reports extracellular uricase enzyme isolation and characterization from strain UR1 of Alcaligenes spp. from Western Saudi Arabia. The strain efficiently produced highly active extracellular uricase for therapeutic applications. It offers a simplified enzyme purification approach rather than complicated intracellular enzyme purification from other microbes. Strain UR1 exhibited significantly higher uricase synthesis potential [916 U/mg (specific activities) and 275 U/ml (volume)]. The study optimized the conditions (37°C and pH 7.4) for 10% enhanced uricase production in the BT medium where sucrose served as the carbon source. Uricase enzyme remained stable at various pH levels (5-9) up to 50°C, however, the optimal activity was noted at 40°C and pH 7.5. The strain was sensitive to EDTA-like inhibitors. Ca2+ improved the strain activity, which could yield potent formulations for clinical and industrial applications. This novel aspect presents Alcaligenes spp. strain UR1 as a promising candidate for the treatment of hyperuricemia and gout. It offers an efficient and inexpensive alternative for uricase synthesis at the industrial scale. These findings encourage further investigations regarding genetic aspects of uricase for improved bioprocessing and therapeutic applications.

Hypouricemic effect of sodium glucose transporter-2 inhibitors: a network meta-analysis and meta-regression of randomized clinical trials

BACKGROUND

Sodium-glucose cotransporter-2 inhibitors (SGLT2is) are known for their cardiovascular benefits, but their impact on serum uric acid levels is not well understood. This study evaluates the hypouricemic effects of SGLT2is and their potential cardiovascular implications.

METHODS

A network meta-analysis was performed, including 56 studies (16,788 participants) contributing data to the meta-analysis. The effects of SGLT2is on serum uric acid levels were analyzed with weighted mean difference (WMD) as the effect estimate. Bootstrapped meta-analysis, trial sequential analysis, and meta-regression were utilized to validate the findings and assess the influence of covariates. The certainty of the evidence was evaluated.

RESULTS

The analysis revealed that SGLT2is significantly reduced serum uric acid levels (WMD: -40.01 μmol/L). Specific reductions were noted for ertugliflozin (-42.17 μmol/L), dapagliflozin (-40.28 μmol/L), empagliflozin (-46.75 μmol/L), canagliflozin (-35.55 μmol/L), and ipragliflozin (-10.48 μmol/L). Both low and high doses were effective, with empagliflozin showing the highest efficacy. No significant associations were found with covariates. The evidence was of moderate certainty.

CONCLUSION

SGLT2is significantly lower serum uric acid levels, with empagliflozin being the most effective. These findings suggest a potential role in reducing cardiovascular risk. Further research is needed to explore their effects on hyperuricemic patients, and monitoring serum uric acid levels is recommended.

Exploring the structures and molecular mechanisms of bioactive compounds from marine foods for hyperuricemia prevention: a systematic review

Hyperuricemia, characterized by an elevation in serum uric acid (UA) levels, stands as a significant metabolic ailment threatening human well-being. Presently, dietary adjustments have become a crucial strategy in managing serum UA levels among individuals grappling with hyperuricemia and gout. Given its unique ecosystem, the ocean hosts a plethora of organisms boasting distinct structures and active components. The marine bioactive substances, such as bioactive peptides, polysaccharides, lipids, and small molecules, have garnered attention in the research and development of modern functional foods and biomedicine due to their profound efficacy and distinctive compositions. Notably, the functional components of marine foods have been studied for their potential in preventing hyperuricemia. However, the precise molecular mechanism underlying their actions remain incompletely elucidated. This review article highlights the diversity of marine active compounds and the latest progress in understanding urate-lowering mechanism. Principal mechanisms primarily encompass the regulation of UA metabolism, maintenance of intestinal homeostasis, mitigation of inflammatory responses, and alleviation of oxidative stress. Furthermore, we scrutinized the constraints of prior studies and provided recommendations. In sum, this article furnished a valuable resource concerning the intervention of bioactive compounds sourced from marine foods in the context of hyperuricemia.

A case of transient elevation of creatinine caused by severe hyperuricemia

BACKGROUND

To explore the underlying causes of significant fluctuations in creatinine levels within three days due to transient and severe uric acid elevation, and to provide evidence for the interpretation of abnormal test results and clinical diagnosis and management.

METHODS

The issues were resolved by retesting the samples, comparing results across different detection platforms, and analyzing the reaction curve. We comprehensively reviewed patients' general conditions, imaging examinations, and treatments. Additionally, we compared pre- and post-admission changes in laboratory indices and performed an extensive literature search for comprehensive analysis.

RESULTS

At the patient's first visit, the levels of uric acid (UA), creatinine (CR), and urea (UREA) were measured at 891 umol/L, 211 umol/L, and 7.8 mmol/L, respectively using a Roche full-automatic biochemical analyzer and its corresponding reagents. Subsequent testing yielded 917 umol/L, 211 umol/L, and 8.3 mmol/L for UA, CR, and UREA. After retesting with the Beckman automatic biochemical analyzer and its corresponding reagents, the results for UA, CR, and UREA were 1013 umol/L, 221 umol/L, and 7.75 mmol/L, respectively. The results of the two detection systems were in agreement. A supplementary measurement of Cystatin C (CYSC) at 1.69 mg/L indicates renal dysfunction, consistent with the observed increase in CR levels and ruling out false elevation due to assay-related issues. At 48 h post-admission, untreated, the levels of blood UA, CR, and UREA decreased to 567umol/L, 77umol/L, and 5.1 mmol/L, respectively. Through literature review and analysis, it was determined that the transient abnormal increase in the patient's creatinine level may be attributed to a substantial accumulation of uric acid crystals obstructing the renal tubules, leading to an impediment in renal tubular excretion which subsequently resolves spontaneously.

CONCLUSION

Severe hyperuricemia may result in a transient increase in blood CR levels and could potentially lead to the development of acute uric acid nephropathy. When a clinical laboratory encounters test results inconsistent with the clinical manifestations, it is essential to not only address any potential detection issues but also proactively investigate the underlying reasons for abnormal test results through comprehensive literature reviews and other rigorous methodologies.

U-shaped relationship between uric acid levels and all-cause mortality in patients with hypertension

A correlation between UA levels and the development of hypertension has been demonstrated. However, the relationship between UA and all-cause mortality in patients with hypertension remains underexplored. A nonlinear association between UA and all-cause mortality across sexes was observed through smoothed curve fitting. The correlation between UA and all-cause mortality was calculated by threshold and saturation effect analysis, along with Cox regression models. The stability of the results in the presence of different comorbidities was verified through stratified analysis for interaction testing. Smoothed curve fitting was also used to examine the association between UA and various diseases. The association between UA and all-cause mortality in patients with hypertension exhibited a U-shaped curve, with inconsistent inflection points between the sexes. In male patients with hypertension, all-cause mortality gradually decreased with increasing UA levels when UA levels were ≤ 7.2 mg/dL (HR  0.975; 95% CI 0.929-1.024) and gradually increased with increasing UA levels when UA levels were > 7.2 mg/dL (HR  1.204; 95% CI 1.120-1.294). Similar findings were observed in female patients with hypertension, with UA as a protective factor when UA levels were ≤ 5.1 mg/dL (HR 0.902; 95% CI 0.820-0.991) and a risk factor when UA levels were > 5.1 mg/dL (HR 1.120; 95% CI 1.072-1.169). The association between UA and all-cause mortality in patients with hypertension exhibits a U-shaped curve. All-cause mortality tends to decrease and then increase with increasing UA levels, with the inflection point varying between sexes.

Uric Acid and Atherosclerosis in Patients with Chronic Kidney Disease: Recent Progress, Mechanisms, and Prospect

Background

Chronic kidney disease (CKD) is a prevalent global health concern, significantly linked to increased cardiovascular morbidity and mortality. Among various risk factors, uric acid (UA) has emerged as a potentially modifiable contributor to cardiovascular complications in CKD patients.

Summary

Elevated serum uric acid levels frequently occur in individuals with CKD and are associated with the development of atherosclerosis (AS). Uric acid has been demonstrated to exacerbate inflammatory processes, promote oxidative stress, and cause endothelial dysfunction, which are critical factors that drive the formation of atherosclerotic plaques. Furthermore, high uric acid levels can worsen renal function, establishing a detrimental cycle that amplifies cardiovascular risk.

Key Messages

This review investigates the complex interconnection between UA and AS in patients with CKD, highlighting the underlying mechanisms and therapeutic considerations. A more profound comprehension of this relationship is essential for enhancing cardiovascular health and outcomes in this vulnerable population.

Population pharmacokinetics and dosage optimization of linezolid in Chinese older patients

PURPOSE

To assess the pharmacokinetics and pharmacodynamics of linezolid in a retrospective cohort of hospitalized Chinese older patients.

METHODS

Patients > 60 years of age, who received intravenous linezolid (600 mg), were included. A population pharmacokinetics (PPK) model was established using nonlinear mixed-effects modeling. The predictive performance of the final model was assessed using goodness-of-fit plots, bootstrap analyses, and visual predictive checks. Monte Carlo simulations were used to evaluate the achievement of a pharmacodynamics target for the area under the serum concentration-time curve/minimum inhibitory concentration (AUC0-24/MIC).

RESULTS

A total of 210 samples were collected from 120 patients. A one-compartment PPK model with linear elimination best predicted the linezolid plasma concentrations. Linezolid clearance (CL) was 4.22 L h-1 and volume of distribution (Vd) was 45.80 L; serum uric acid (SUA) was a significant covariate of CL.

CONCLUSION

The results of this study indicated that the standard dose was associated with a risk of overexposure in older patients, particularly those with high SUA values; these patients would benefit from a lower dose (300 mg every 12 h).

Co-delivery of indomethacin and uricase as a new strategy for inflammatory diseases associated with high uric acid

Uric acid is the final metabolite in humans. High level of uric acid chronically induces urate deposition, aggravates kidney damage, and concomitantly causes an increase in inflammatory factors. Alleviating acute inflammation and decreasing uric acid levels are the key points in the treatment of inflammatory diseases associated with high uric acid. However, a drug delivery system that combines anti-inflammatory and uric acid reduction functions at the same time remains a challenge to be settled. Here, we designed a nanocrystal-based co-delivery platform, IND Nplex, characterized by loading of indomethacin (IND) and uricase. Compared with free IND or uricase, IND Nplex possessed a better anti-inflammatory effect by restraining the release of inflammation-related factors in vitro. In addition, pharmacokinetic and biodistribution studies revealed that IND Nplex significantly prolonged the retention time in vivo and was more concentrated in the kidney. In acute gouty arthritis model rats, IND Nplex markedly relieved ankle joint swelling and mitigated synovial inflammation. In acute kidney injury model rats, IND Nplex indicated better biocompatibility and significant amelioration of renal fibrosis. Moreover, IND Nplex showed the effect of anti-inflammatory and improved renal function via determination of inflammatory factors and biochemical markers in the serum and kidney. In conclusion, these results indicate that IND Nplex exerts anti-inflammatory activity and uric acid-lowering effect and could become a promising candidate for the treatment of uric acid-related diseases.

Fractional Excretion of Urate is Positively Associated with Type 2 Diabetes in HUA Patients: A Cross-Sectional Study

Purpose

People with hyperuricemia (HUA) are often related to metabolic disorders such as diabetes, metabolic syndrome (MetS), and obesity. However, the correlation between excretion of uric acid and these diseases is unclear. Our study aimed to explore the relationship between uric acid excretion and type 2 diabetes (T2D).

Methods

A total of 228 HUA patients from Tianjin Medical University General Hospital from 2022 to 2023 were included in this study. We collected demographic, biochemical, and anthropometric data on each subject. Urine uric acid excretion (UUAE) was calculated enzymatically from a single urine collection that lasted 24 hours. And fractional excretion of uric acid (FEUA) was calculated from serum uric acid and creatinine and uric acid and creatinine. Binary logistic regression modeling assessed the association between uric acid excretion and T2D.

Results

Of the 228 subjects, 13.4% had T2D and 48.7% had obesity. The obesity group had a lower FEUA (p<0.05) and a higher UUAE compared to the control group (p<0.05). And FEUA had a stronger correlation with the risk of T2D (p<0.001). Also, there was a negative association between BMI and FEUA and a positive link between BMI and UUAE in the outpatients.

Conclusion

Increased FEUA levels were significantly associated with T2D in HUA patients. Therefore, routine calculating of FEUA is essential for proper diagnosis and appropriate treatment T2D of in HUA patients.

Recent developments and future perspectives of microfluidics and smart technologies in wearable devices

Wearable devices are gaining popularity in the fields of health monitoring, diagnosis, and drug delivery. Recent advances in wearable technology have enabled real-time analysis of biofluids such as sweat, interstitial fluid, tears, saliva, wound fluid, and urine. The integration of microfluidics and emerging smart technologies, such as artificial intelligence (AI), machine learning (ML), and Internet of Things (IoT), into wearable devices offers great potential for accurate and non-invasive monitoring and diagnosis. This paper provides an overview of current trends and developments in microfluidics and smart technologies in wearable devices for analyzing body fluids. The paper discusses common microfluidic technologies in wearable devices and the challenges associated with analyzing each type of biofluid. The paper emphasizes the importance of combining smart technologies with microfluidics in wearable devices, and how they can aid diagnosis and therapy. Finally, the paper covers recent applications, trends, and future developments in the context of intelligent microfluidic wearable devices.

Uric acid in predicting the traumatic rhabdomyolysis induced acute kidney injury; a systematic review and meta-analysis

OBJECTIVE

The objective of this systematic review and meta-analysis was to assess the value of uric acid in predicting acute kidney injury caused by traumatic rhabdomyolysis.

METHODS

The search was conducted in MEDLINE, Scopus, Embase and Web of Science until November 1, 2023. Based on the inclusion and exclusion criteria, the articles were included by two independent researchers. Data regarding study design, patient characteristics, number of patients with and without AKI, mean and SD of uric acid and prognostic characteristics of uric acid were extracted from relevant studies. STATA version 17.0 was used to compute pooled measures of standardized mean differences, odds ratios, and diagnostic accuracy. I2 and chi-square tests were used to assess heterogeneity between studies.

RESULTS

We found 689 non-redundant studies, 44 of them were potentially relevant. Six articles met the inclusion criteria and were included in the review. The results of the meta-analysis confirmed that there was a significant correlation between serum uric acid levels and the occurrence of AKI (SMD = 1.61, 95% CI = 0.69 to 2.54, I2 = 96.94%; p value = 0.001). There were no significant publication biases.

CONCLUSION

According to this meta-analysis, uric acid levels could be considered as a predictor of acute kidney injury following traumatic rhabdomyolysis.

Si Miao San relieves hyperuricemia by regulating intestinal flora

This study seeks to investigate the therapeutic effects of Si Miao San (SMS) on hyperuricemia and its underlying mechanisms, particularly focusing on the role of intestinal flora. The key components of SMS were identified using high-performance liquid chromatography (HPLC). To establish a rat model of hyperuricemia, an intraperitoneal injection of potassium oxonate was performed, followed by oral administration of various concentrations of SMS. The study evaluated the status of hyperuricemia, renal pathology, xanthine oxidase (XO) activity, and intestinal flora. Utilizing HPLC, we identified five active components of SMS. Following SMS intervention, there was a significant reduction in serum levels of uric acid (UA), blood urea nitrogen, and creatinine, accompanied by an increase in urine UA levels in rats with hyperuricemia. Distinct pathological injuries were evident in the renal tissues of hyperuricemic rats, and these were partially alleviated following SMS intervention. Moreover, SMS exhibited a dose-dependent reduction in XO activity both in the serum and hepatic tissues. Notably, SMS contributed to an enhancement in the diversity of intestinal flora in hyperuricemic rats. The intervention of SMS resulted in a reduction in the abundance of certain bacterial species, including Parabacteroides johnsonii, Corynebacterium urealyticum, and Burkholderiales bacterium. This suggests that SMS may exert anti-hyperuricemia effects, potentially by modulating the composition of intestinal flora.

Association Between Serum Uric Acid Levels and Oxido-Inflammatory Biomarkers With Coronary Artery Disease in Type 2 Diabetic Patients

BACKGROUND

Cardiovascular disease signifies a major cause of morbidity and mortality among patients with type 2 diabetes mellitus (T2DM). Serum uric acid (SUA) levels are elevated during the initial phases of impaired glucose metabolism. This work was designed to explore the association between SUA levels, serum oxido-inflammatory biomarkers, and the risk of coronary artery disease (CAD) in T2DM patients as the primary outcome. The secondary outcome was to assess the prognostic role of SUA in the prediction of the risk of CAD in T2DM patients.

METHODS

In this case-control study, we enrolled 110 patients with T2DM who were further divided into patients with CAD and without CAD. In addition, 55 control participants were stringently matched to cases by age.

RESULTS

Diabetic patients with CAD had significantly higher serum levels of the inflammatory biomarkers and the oxidative malondialdehyde but significantly lower levels of serum total antioxidant capacity (TAC) compared with the controls and diabetic patients without CAD. Significant positive correlations existed between SUA levels and serum levels of the inflammatory biomarkers and malondialdehyde, while a significant negative correlation existed between SUA levels and serum TAC. SUA demonstrated an accepted discrimination ability. SUA can differentiate between T2DM patients with CAD and patients without CAD, an area under the curve of 0.759.

CONCLUSIONS

Elevated serum levels of SUA and oxido-inflammatory biomarkers are associated with an increased risk of CAD in T2DM. SUA levels reflect the body's inflammatory status and oxidant injury in T2DM. SUA could be utilized as a simple biomarker in the prediction of CAD risk in T2DM.

Investigation of the Inhibition Mechanism of Xanthine Oxidoreductase by Oxipurinol: A Computational Study

Xanthine oxidoreductase (XOR) is an enzyme found in various organisms. It converts hypoxanthine to xanthine and urate, which are crucial steps in purine elimination in humans. Elevated uric acid levels can lead to conditions like gout and hyperuricemia. Therefore, there is significant interest in developing drugs that target XOR for treating these conditions and other diseases. Oxipurinol, an analogue of xanthine, is a well-known inhibitor of XOR. Crystallographic studies have revealed that oxipurinol directly binds to the molybdenum cofactor (MoCo) in XOR. However, the precise details of the inhibition mechanism are still unclear, which would be valuable for designing more effective drugs with similar inhibitory functions. In this study, molecular dynamics and quantum mechanics/molecular mechanics calculations are employed to investigate the inhibition mechanism of XOR by oxipurinol. The study examines the structural and dynamic effects of oxipurinol on the pre-catalytic structure of the metabolite-bound system. Our results provide insights on the reaction mechanism catalyzed by the MoCo center in the active site, which aligns well with experimental findings. Furthermore, the results provide insights into the residues surrounding the active site and propose an alternative mechanism for developing alternative covalent inhibitors.

Sex distinctive patterns in the association between serum bicarbonate and uric acid levels among healthy adults. Qatar biobank data

Background

Uric acid is the final product of purine metabolism and is a potent plasma antioxidant but with pro-inflammatory effects. At high levels, it may increase the risk of developing multiple chronic diseases, such as gout, atherosclerosis, hypertension, and renal diseases. The aim of this study was to assess the sex-specific association between serum bicarbonate and uric acid levels among healthy adults.

Methodology

This retrospective cross-sectional study included 2,989 healthy Qatari adults (36.4 ± 11.1  years) from the Qatar Biobank database. Serum uric acid and bicarbonate levels were estimated alongside other serological markers. Participants free from chronic diseases were divided into four quartiles based on serum bicarbonate levels. The sex-specific relationship between serum bicarbonate and uric acid levels was assessed through univariate and multivariate analyses.

Results

In men, low serum uric acid levels were significantly associated with higher quartiles of serum bicarbonate levels after adjusting for age. The association remained significant after further adjustment for BMI, smoking, and renal function. The subgroup analysis using the restricted cubic spline method confirmed a significant dose-response association between the variation coefficients of uric acid by serum bicarbonate level in men with adjustments for age, BMI, smoking, and renal function. In women, no significant association was found between quartiles of serum bicarbonate and uric acid levels following the same adjustments. However, using the restricted cubic spline method, a significant bidirectional relation was demonstrated between serum bicarbonate and the variation coefficients of uric acid that were positive for serum bicarbonate levels below 25 mEq/L and negative at higher levels.

Conclusion

Serum bicarbonate levels are linearly associated with reduced serum uric acid levels among healthy adult men, which may be a potential protective factor against hyperuricemia-related complications. Further research is needed to determine the underlying mechanisms.

Preparation and Application of Nanozymes with Uricase-Like Activity Based on Molecularly Imprinted Polymers

Nanozymes have advantages over natural enzymes in terms of efficiency, stability, and economy. MVSM (Mixed Valence State MOF) is a nano-oxidase with uricase-like activity that may catalyze uric acid (UA) in the body into allantoin and H₂ O₂ to treat gout and hyperuricemia by substituting natural uricase. However, it cannot specifically identify and choose UA. To increase the selectivity and affinity of MVSM for UA, the composite material MVSM@MIP is innovatively synthesized using a new synthetic approach termed the "two-step synthesis method," which may prevent UA from being oxidized by MVSM during manufacture in this study. At the same time, this study also provides experimental proof of the effective creation of the material, the advantages of the "two-step synthesis approach," and the high selectivity and affinity of MVSM@MIP for UA. Based on these findings, the suggested technique may be used to effectively catalyze uric acid in human urine with high activity.

The prevalence of hyperuricemia and its correlates in Zhuang nationality, Nanning, Guangxi Province

BACKGROUND

Hyperuricemia has an increasing incidence in various regions year by year, in this study, we evaluated the prevalence of hyperuricemia in a routine physical examination in Nanning, Guangxi Province, and analyzed the influencing factors of hyperuricemia, aiming to provide evidence for the prevention and treatment of hyperuricemia and related diseases.

METHODS

Data were collected from 1957 patients who underwent physical examinations at the First Affiliated Hospital of Guangxi Medical University in China since 2017. Questionnaires were structured, including subjects' demographics, lifestyle, personal history, chronic disease history, medication history, etc. UA (uricase method), TC (cholesterol oxidase method), TG (glycerol phosphate oxidase method), HDL-C (direct method), LDL-C (direct method), BUN (rate method), creatinine (sarine oxidase method), and GLU (oxidase-peroxidase method) were detected. Independent risk factors for hyperuricemia were determined by bivariate non-conditional logistic regression analysis.

RESULTS

The overall prevalence of hyperuricemia was 16.6% (19.5% in males and 14.9% in females). Gender, waist circumference, BMI, the proportion of drinking, hypertension, high education, serum concentrations of TC, TG, LDL-C, BUN, and creatinine were significantly higher and the serum concentration of HDL-C was significantly lower in patients with and without hyperuricemia (all p < 0.05). Waist circumference, BMI, BUN, and creatinine were independent risk factors for hyperuricemia.

CONCLUSION

The prevalence of hyperuricemia is very high in Guangxi. Public health lectures should be conducted to encourage people to establish a healthy lifestyle and strengthen early intervention for hyperuricemia to reduce the risk of cardio-cerebrovascular and other related diseases.

Association between gut microbiota and elevated serum urate in two independent cohorts

OBJECTIVES

Hyperuricemia is a precursor to gout and is often present in other metabolic diseases that are promoted by microbiome dysbiosis; however, no study has examined the association of gut microbiota with hyperuricemia and serum urate in humans.

METHODS

Study participants were derived from a community-based observational study, the Xiangya Osteoarthritis Study (discovery cohort). Hyperuricemia was defined as the presence of serum urate level >357 μmol/L for women and >416 μmol/L for men. Gut microbiota was analyzed using 16S rRNA sequencing from stool samples. We examined the relation of microbiota dysbiosis (i.e., richness, diversity, composition, and relative abundance of microbiota taxa) and predicted functional pathways to prevalent hyperuricemia and serum urate levels. We verified the associations in an independent observational study, the Step Study (validation cohort).

RESULTS

The discovery cohort consisted of 1,392 rural participants (mean age: 61.3 years; women: 57.4%; hyperuricemia: 17.2%). Participants with hyperuricemia had decreased richness and diversity, altered composition of microbiota, and lower relative abundances of genus Coprococcus compared with those with normouricemia. Predicted Kyoto Encyclopedia of Genes and Genomes metabolism pathways belonged to amino acid and nucleotide metabolisms were significantly altered in individuals with hyperuricemia compared with those with normouricemia. Gut microbiota richness, diversity and low relative abundances of genus Coprococcus were also associated with high levels of serum urate. These findings were replicated in the validation cohort with 480 participants.

CONCLUSIONS

Gut microbiota dysbiosis was associated with elevated serum urate levels. Our study raises the possibility that microbiota dysbiosis may modulate serum urate levels.

The association between vitamin D3 and diabetes in both hyperuricemia and non-hyperuricemia populations

BACKGROUND

Previous studies have shown that hyperuricemia is involved in diabetes, obesity, hypertension, chronic kidney disease, and other diseases. At the same time, studies have shown that vitamin D3 levels in the body are linked to the onset of diabetes. However, there is currently no sufficient evidence to prove whether this connection is affected by the uric acid level. Therefore, we attempted to investigate the association between vitamin D3 content and the occurrence of diabetes in populations with different uric acid levels though the data of NHANES database from 2009 to 2018.

METHOD

Using the NHANES database, we performed a cross-sectional analysis. The participants were chosen based on stringent inclusion and exclusion requirements. This study finally included a total number of 16,735 individuals. Multivariate logistic regression analysis was used to investigate the association between vitamin D3 and diabetes mellitus in hyperuricemia and non-hyperuricemia patients after complete adjustment, and multivariate linear regression analysis was used to illustrate the association between vitamin D3 and uric acid.

RESULT

The results showed that the association between vitamin D3 and diabetes was weakened in hyperuricemia patients (OR 0.95 (0.92,0.98)). An independent association was discovered between vitamin D3 and uric acid (β -0.12 (-0.16, -0.07)) in all groups of population.

CONCLUSIONS

This study shows that vitamin D3 content is associated with the incidence of diabetes in people with high level of uric acid. This study offers a fresh perspective on the elements that influence the etiology of diabetes in hyperuricemia patients.

Study on performance of mimic uricase and its application in enzyme-free analysis

Nanozymes were the novel research field to replace natural enzymes because of stability and low cost. However, the research on nanozymes was mainly focused on peroxidase, and there was little research about nanozymes with oxidase-like activity, especially mimic oxidase of small molecules related to human physiology. High levels of uric acid (UA) in the body can cause hyperuricemia and gout. And natural uricase cured this disease because it could oxidize UA. The oxidase-like activity of mixed valence state metal organic frameworks with cerium (MVSM) had been studied, but MVSM was found to have uricase-like activity in this article. The catalytic process of UA with MVSM was studied by a variety of analytical methods, which was similar to the natural uricase except for further oxidation of H₂O₂. The catalytic activity constants of MVSM were acquired by the Michaelis-Menten equation. MVSM had a better ability to catalyze UA in in vivo and in vitro experiments. An enzyme-free analysis-based mimic uricase for UA was established. All the experimental results proved that MVSM had a good prospect to replace the natural uricase. A nanomaterial, mixed valence state Ce-MOF (MVSM), with uricase-like activity has been found in vivo and in vitro. This material has potential to be a fluorescent analysis for detecting uric acid without uricase.

Relationship between serum uric acid level and nonalcoholic fatty liver disease in type 2 diabetes patients

This study aimed to investigate the association between serum uric acid (SUA) level and nonalcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes (T2DM).T2DM patients hospitalized in the Department of Hepatology, Yantai Qishan Hospital, between April 2012 and December 2018 were classified into the NAFLD group and the non-NAFLD group. Clinical data, glucose and lipid metabolism biomarkers, and liver and kidney function parameters were retrospectively collected.Five hundred eighty-three T2DM patients met the inclusion and exclusion criteria; 227 patients were included in the non-NAFLD group and 356 patients were included in the NAFLD group. Multiple linear regression analyses showed that SUA was positively correlated with body mass index (P = .003), triglycerides (P = .009), aspartate aminotransferase (P = .036), and alanine aminotransferase (P = .038) and negatively correlated with estimated glomerular filtration rate (P < .001) in T2DM patients. Multivariate regression analyses demonstrated that after adjusting for confounding factors, the SUA tertile was still significantly associated with NAFLD occurrence in T2DM patients (P for trend = .008). With reference to SUA tertile I, the odds ratios for NAFLD in the SUA tertile II and tertile III groups were 1.729 (95% confidence interval [CI]: 1.086-2.753) and 2.315 (95% CI: 1.272-4.213), respectively.The level of SUA in T2DM patients was associated with the occurrence of NAFLD. Elevated SUA was associated with a significantly increased prevalence of NAFLD. The SUA level was an independent risk factor for NAFLD occurrence in patients with T2DM.

Hyperuricemia causes kidney damage by promoting autophagy and NLRP3-mediated inflammation in rats with urate oxidase deficiency

Epidemiological research has shown that elevated serum urate concentration is a risk factor for the development of kidney disease; however, the mechanisms underlying this process have not yet been elucidated. To examine the role of urate in the kidney, we used Wistar rats to functionally disrupt expression of urate oxidase (UOX) by using the CRISPR/Cas9 system. In comparison to wild-type (WT) rats, serum urate levels spontaneously and persistently increased in UOX-KO rats, without showing a significant decrease in survival rate. Architecture and function of the kidneys in UOX-KO rats were impaired. Injury to the kidney resulted in increased interstitial fibrosis, macrophage infiltration, increased expression of NLRP3 and IL-1β, and activation of multiple cell-signaling pathways associated with autophagy, such as AMPK, p38 MAPK, ERK and JNK pathways. Inhibition of autophagy with the PI3K inhibitor 3-MA abrogated the development of kidney damage and attenuated renal fibrosis, macrophage infiltration, and expression of NLRP3 and IL-1β in injured kidneys. In conclusion, the UOX-KO rat is a great model to study hyperuricemia-related diseases. Hyperuricemia-induced autophagy and NLRP3-dependent inflammation are critically involved in the development of renal damage and, therefore, highlight the inhibition of autophagy and inflammation in search of therapeutic strategies to treat uric acid nephropathy.

Serum Urate Lowering Therapy Using Allopurinol Improves Serum 25 Hydroxy Vitamin D in Stage 3-5 CKD Patients: A Pilot Study

BACKGROUND

Recent studies have demonstrated negative associations of serum uric acid (SUA) with serum 25 hydroxy vitamin D (25 [OH] vit D) among CKD patients.

OBJECTIVE

The aim of the study was to look for the impact of hypouricemic therapy using allopurinol on serum level of 25 (OH) vit D in CKD patients.

CASES AND METHODS

Seventy-two CKD stage 3-5 patients were selected to this study. Patients with SUA above 7 mg/dL were allocated to hypouricemic therapy using allopurinol (group I). A control group of cases not suffering marked increase in SUA were included as control group (group II). All cases were followed up for 3 months. Serum Cr, SUA, ionized calcium (SiCa), phosphorus, 25 (OH) vitD, parathyroid hormone (PTH), and 24-h urine protein were estimated at entry and by the end of the study.

RESULTS

At least 20 cases completed the study in each group. Serum 25 (OH) vit D significantly increased in group I (26.4 [14.1] vs. 39.6 [14.8] at entry vs. at end of the study, p < 0.001). In addition, SUA, PTH, and urine protein significantly decreased (11 [1.6] vs. 3.95 [0.58] mg/dL, 267.5 [97.5] vs. 225.5 [153] ng/mL, and 2.7 [1.18] vs. 1.5 [1.08] gm/day, p < 0.001, = 0.043, and <0.001 respectively). SiCa and phosphorus significantly increased (4.4 [0.3] vs. 5.2 [0.5] mg/dL and 4.25 [0.72] vs. 4.9 [0.75] mg/dL, p < 0.001 and = 0.007, respectively).

CONCLUSION

This study supports a negative causal relationship between SUA and serum 25 (OH) vit D. Further studies are still needed to confirm this conclusion.

[Asymptomatic Hyperuricemia and Risk Of Cardiovascular and Renal Diseases]

Asymptomatic hyperuricemia (HU) is common in the population and significantly contributes to the general cardiovascular risk. Despite extensive study of this condition there is still no conclusive answers to questions about detection of asymptomatic HU and its effect on the risk for development and progression of cardiovascular and kidney diseases. This review summarizes key information about these issues, which has been accumulated by the present time.

Multiple-Purpose Connectivity Map Analysis Reveals the Benefits of Esculetin to Hyperuricemia and Renal Fibrosis

Hyperuricemia (HUA) is a risk factor for chronic kidney disease (CKD). Serum uric acid (SUA) levels in CKD stage 3–4 patients closely correlate with hyperuricemic nephropathy (HN) morbidity. New uric acid (UA)-lowering strategies are required to prevent CKD. The multiple-purpose connectivity map (CMAP) was used to discover potential molecules against HUA and renal fibrosis. We used HUA and unilateral ureteral occlusion (UUO) model mice to verify renoprotective effects of molecules and explore related mechanisms. In vitro experiments were performed in HepG2 and NRK-52E cells induced by UA. Esculetin was the top scoring compound and lowered serum uric acid (SUA) levels with dual functions on UA excretion. Esculetin exerted these effects by inhibiting expression and activity of xanthine oxidase (XO) in liver, and modulating UA transporters in kidney. The mechanism by which esculetin suppressed XO was related to inhibiting the nuclear translocation of hexokinase 2 (HK2). Esculetin was anti-fibrotic in HUA and UUO mice through inhibiting TGF-β1-activated profibrotic signals. The renoprotection effects of esculetin in HUA mice were associated with lower SUA, alleviation of oxidative stress, and inhibition of fibrosis. Esculetin is a candidate urate-lowering drug with renoprotective activity and the ability to inhibit XO, promote excretion of UA, protect oxidative stress injury, and reduce renal fibrosis.

Gender and chronic kidney disease in ankylosing spondylitis: a single-center retrospectively study

BACKGROUND

Ankylosing spondylitis (AS) is a well-known male-predominant inflammatory disease. This study aimed to assess the gender disparity in chronic kidney disease (CKD) in AS patients in China.

METHODS

AS patients were retrospectively studied at Peking Union Medical College hospital between January 2002 and June 2018.

RESULTS

Among 616 patients with AS, 154 (25.0%) patients had CKD (age, 41.8 ± 14.2 years; male:female, 3.2:1). Overall, 80 (13.0%) patients had only microscopic hematuria, 62 (10.1%) had proteinuria with or without hematuria, and 33 (5.4%) exhibited a reduced estimated glomerular filtration rate (eGFR, ≤60 mL/min/1.73 m²). Male CKD patients had more frequent proteinuria (p < 0.01), less microscopic hematuria only (p < 0.01), and lower eGFR (p = 0.04) compared with females. CKD was independently associated with hyperuricemia and total cholesterol in females, and with hyperuricemia, hypertension, and serum albumin in males. After follow-up for 1-7 years, five patients required renal replacement therapy including two patients who were already at stage 5 CKD when enrolled and three patients whose creatinine doubled. One patient died in the male group. No patients in the female group showed progression of renal dysfunction.

CONCLUSIONS

CKD is a common comorbidity in patients with AS. Male patients are more likely to develop severe manifestations compared with female patients. Hyperuricemia was a strong independent risk factor for CKD in both genders, while hypertension and low serum albumin were risk factors for CKD only in males.

Protective Effects of α-Lipoic Acid on Vascular Oxidative Stress in Rats with Hyperuricemia

The aim of the present study was to observe the protective effects of α-lipoic acid (ALA) on vascular injury in rats with hyperuricemia (HUA). The ALA treatment groups (10, 30 and 90 mg/kg, respectively) were administered with ALA via gavage for 2 weeks. Subsequently, the levels of blood urea nitrogen (BUN), creatinine (CREA), uric acid (UA), total cholesterol (TC), high density lipoprotein-C (HDL-C) and low density lipoprotein-C (LDL-C) were measured; the activities of glutathione peroxidase (GSH-Px), catalase (CAT), malonaldehyde (MDA), superoxide dismutase (SOD) and xanthine oxidase (XOD) were also determined. The thoracic aorta of rats in each experimental group was observed under a light microscope; ultrastructural analysis was performed. SOD and CAT protein contents were investigated by Western blotting. The results revealed that: i) Compared with the model group, the levels of UA were decreased in the ALA groups and the levels of BUN, CREA, TC, and LDL-C decreased in the 30 and 90 mg/kg ALA groups (P<0.05); ii) compared with the model group, the activities of GSH-Px, SOD and XOD were increased and the levels of MDA were reduced in the 90 mg/kg ALA group (P<0.05); and iii) in the model and 10 mg/kg ALA groups, edema and shedding were observed in endothelial cells. Compared with the model and 10 mg/kg ALA groups, the 30 and 90 mg/kg ALA groups exhibited fewer swollen endothelial cells. In summary, the results of the present study indicated that HUA resulted in vascular oxidative stress injury and decreased the activity of antioxidative enzymes, which leads to endothelial cell damage and vascular lesions. ALA may serve as a therapeutic agent for the treatment of HUA-induced endothelial dysfunction.

Increased urinary glucose excretion is associated with a reduced risk of hyperuricaemia

AIM

To investigate the association of urinary glucose excretion with levels of serum uric acid in adults with newly diagnosed diabetes.

METHODS

A total of 597 people with newly diagnosed diabetes, confirmed in an oral glucose tolerance test, were included in the present study. The participants were divided into two groups: 142 participants with low urinary glucose excretion and 455 with high urinary glucose excretion. Demographic characteristics and clinical variables were evaluated. The association of urinary glucose excretion with uric acid was analysed using multivariable regression analysis.

RESULTS

The low urinary glucose excretion group had a significantly higher prevalence of hyperuricaemia than the high urinary glucose excretion group. Moreover, urinary glucose excretion was negatively associated with uric acid level. The correlation remained significant after adjusting for potential confounders, including gender, age, fasting plasma glucose, 2-h plasma glucose and BMI. The results also showed that participants with high urinary glucose excretion were at decreased risk of hyperuricaemia (odds ratio 0.47, 95% CI 0.27-0.80; P = 0.006).

CONCLUSION

Urinary glucose excretion was independently associated with uric acid level in participants with newly diagnosed diabetes. In addition to lowering blood glucose, promoting urinary glucose excretion may also be an effective approach to reducing serum uric acid levels, especially for people with diabetes complicated with hyperuricaemia.

Association of serum uric acid change with mortality, renal function and diuretic dose administered in treatment of acute heart failure

BACKGROUND AND AIMS

Hyperuricemia is reportedly associated with poor outcome in acute heart failure (AHF). The association between changes in Uric acid (UA) levels with renal function change, diuretic doses, and mortality in patients with AHF were studied.

METHODS AND RESULTS

Consecutive patients hospitalized with AHF were reviewed (n = 535). UA levels were measured at admission and either at discharge or on approximately the seventh day of admission. Patients with an UA change in the top tertile were defined as having an increase (UA-increase) and were compared to those outside the top tertile (non-UA-increase). The endpoint was all-cause mortality, with a mean follow-up duration of 22.2 months. Patients in the UA-increase group presented with greater creatine increase (P < 0.001), and were administered a higher average daily dose of loop diuretic (P = 0.016) compared with the non-UA-increase group. In-hospital UA-increase was associated with higher risk of mortality even after adjusting for confounding variables including creatine change and diuretic dosage [harzard ratio (HR) 1.53, 95% confidence interval (CI) 1.02-2.30, P = 0.042]. In patients with hyperuricemia on admission, UA-increase was associated with increased mortality (adjusted HR 2.21, 95% CI 1.38-3.52, P = 0.001). Whereas, in those without admission hyperuricemia, UA-increase had no significant association with mortality.

CONCLUSIONS

An increase in UA during in-hospital treatment is associated with an increase in creatine levels and daily diuretic dose. Mortality associated with increased UA is restricted to patients who already have hyperuricemia at admission. A combination of UA levels at admission and UA changes on serial assessment during hospitalization may be additional value in the risk stratification of AHF patients.

Incident gout and chronic Kidney Disease: healthcare utilization and survival

Background

Uncontrolled gout can cause significant joint and organ damage and has been associated with impairments in quality of life and high economic cost. Gout has also been associated with other comorbid diseases, such as chronic kidney disease. The current study explored if healthcare resource utilization (HRU) and survival differs between patients with incident gout in the presence or absence of chronic kidney disease (CKD).

Methods

Clalit Health Services (CHS) data were used to conduct a retrospective population-based cohort study of incident gout between 1/1/2006–31/12/2009. Incident cases of gout were identified and stratified by CKD status and by age group (< 55 and 55+ years). CKD status was defined as a pre-existing diagnosis of chronic kidney disease, chronic renal failure, kidney transplantation, or dialysis at index date. Demographic and clinical characteristics, as well as healthcare resource use, were reported.

Results

A total of 12,940 incident adult gout patients, with (n = 8286) and without (n = 4654) CKD, were followed for 55,206 person-years. Higher rates of HRU were observed for gout patients with CKD than without. Total annual hospital admissions for patients with gout and CKD were at least 3 times higher for adults < 55 (mean = 0.51 vs 0.13) and approximately 1.5 times higher for adults 55+ (mean = 0.46 vs 0.29) without CKD. Healthcare utilization rates from year 1 to year 5 remained similar for gout patients < 55 years irrespective of CKD status, however varied according to healthcare utilization by CKD status for gout patients 55+ years. The 5-year all-cause mortality was higher among those with CKD compared to those without CKD for both age groups (HR_{< 55 years} = 1.65; 95% CI 1.01–2.71; HR_{55+ years} = 1.50; 95% CI 1.37–1.65).

Conclusions

The current study suggests important differences exist in patient characteristics and outcomes among patients with gout and CKD. Healthcare utilization differed between sub-populations, age and comorbidities, over the study period and the 5-year mortality risk was higher for gout patients with CKD, regardless of age. Future work should explore factors associated with these outcomes and barriers to gout control in order to enhance patient management among this high-risk subgroup.

Relationship between serum uric acid and clustering of cardiovascular disease risk factors and renal disorders among Shanghai population: a multicentre and cross-sectional study

OBJECTIVES

To estimate the current prevalence of cardiovascular disease risk factors (CRFs) and renal disorders across serum uric acid (SUA) quartiles, and evaluate the relationships between SUA and CRFs and renal diseases in Shanghai population.

STUDY DESIGN

Observational, cross-sectional study.

SETTING

Data were obtained from the physical check-up of local residents at three hospitals in Shanghai.

PARTICIPANTS

Residents were invited to take part in a physical check-up and provided informed consent. Exclusion criteria were diseases that resemble cancer, hepatic disease, and other coexisting illnesses including autoimmune kidney diseases and renal artery stenosis, individuals treated with xanthine oxidase inhibitors, and those with incomplete information. There are 26 768 individuals in our study.

PRIMARY AND SECONDARY OUTCOME MEASURES

Hyperuricaemia was defined as SUA ≥7 mg/dL in men and ≥6 mg/dL in women or taking xanthine oxidase inhibitors. Subjects were divided into gender-specific quartiles. We estimate the prevalence of CRFs and renal disorders across SUA quartiles. The relationships between SUA and CRFs and renal disorders in both genders were evaluated using logistic regression analysis.

RESULTS

There was a significant increase in the prevalence of major CRFs and renal diseases across SUA quartiles in a separate analysis among men and women (all p trend <0.001). After multiple adjustment, hyperuricaemia positively correlated with obesity (male OR=3.165, p<0.001; female OR=3.776, p<0.001), hypertension (male OR=1.341, p<0.001; female OR=1.289, p=0.006), dyslipidaemia (male OR=2.490, p<0.001; female OR=3.614, p<0.001), chronic kidney disease (male OR=7.081, p<0.001; female OR=11.571, p<0.001) and nephrolithiasis (male OR=1.469, p<0.001; female OR=1.242, p=0.041), but negatively correlated with diabetes mellitus (male OR=0.206, p<0.001; female OR=0.524, p<0.001). There was a stronger association between hyperuricaemia and clustered CRFs as well as chronic kidney disease in women than in men.

CONCLUSIONS

In Shanghai population, concomitant with the elevated level of SUA, the prevalence of CRFs and renal diseases was rising. Hyperuricaemia was significantly associated with CRFs and renal disorders, especially in women.

Examining the effects of uric acid-lowering on markers vascular of calcification and CKD-MBD; A post-hoc analysis of a randomized clinical trial

BACKGROUND

Chronic kidney disease (CKD)-mineral and bone disorder (MBD) is a systemic disorder that leads to vascular calcification and accelerated atherosclerosis. Uric acid has been shown to associate with vascular calcification and with carotid intima-media thickness (CIMT) and to suppress the 1 α-hydroxylase enzyme leading to lower 1,25-dihydroxyvitamin D (1,25(OH)2D) and higher intact parathyroid hormone (iPTH) levels. We hypothesized that lowering serum uric acid would reduce CIMT, calcification propensity, and circulating markers of CKD-MBD in CKD.

METHODS

This is a post-hoc analysis of a randomized, double-blind study of 80 patients with stage 3 CKD and hyperuricemia who received allopurinol or placebo for 12 weeks. CIMT and T50 were measured as markers of vascular disease and serum calcification propensity, respectively. The following markers of CKD-MBD were measured: serum calcium, phosphorus, vitamin D metabolites, iPTH, and fibroblast growth factor-23 (FGF-23). Expression of extra-renal 1α-hydroxylase was evaluated in endothelial cells of study participants.

FINDINGS

Allopurinol successfully lowered serum uric acid levels compared to placebo with an estimate of -3.3 mg/dL (95% C.I. -4.1,-2.5; p < 0.0001). After 12 weeks, however, we found no significant change in CIMT or serum T50. There was not a significant change in vitamin D metabolites, iPTH, FGF-23, or the expression of endothelial 1α-hydroxylase.

CONCLUSION

These data suggest that factors other than uric acid may play a more important role in the regulation of CKD- MBD including vascular calcification and vitamin D metabolism in patients with CKD.

Urinary excretion of uric acid is negatively associated with albuminuria in patients with chronic kidney disease: a cross-sectional study

Background

Increasing evidence has shown that albuminuria is related to serum uric acid. Little is known about whether this association may be interrelated via renal handling of uric acid. Therefore, we aim to study urinary uric acid excretion and its association with albuminuria in patients with chronic kidney disease (CKD).

Methods

A cross-sectional study of 200 Chinese CKD patients recruited from department of nephrology of Huadong hospital was conducted. Levels of 24 h urinary excretion of uric acid (24-h Uur), fractional excretion of uric acid (FEur) and uric acid clearance rate (Cur) according to gender, CKD stages, hypertension and albuminuria status were compared by a multivariate analysis. Pearson and Spearman correlation and multiple regression analyses were used to study the correlation of 24-h Uur, FEur and Cur with urinary albumin to creatinine ratio (UACR).

Results

The multivariate analysis showed that 24-h Uur and Cur were lower and FEur was higher in the hypertension group, stage 3–5 CKD and macro-albuminuria group (UACR> 30 mg/mmol) than those in the normotensive group, stage 1 CKD group and the normo-albuminuria group (UACR< 3 mg/mmol) (all P < 0.05). Moreover, males had higher 24-h Uur and lower FEur than females (both P < 0.05). Multiple linear regression analysis showed that UACR was negatively associated with 24-h Uur and Cur (P = 0.021, P = 0.007, respectively), but not with FEur (P = 0.759), after adjusting for multiple confounding factors.

Conclusions

Our findings suggested that urinary excretion of uric acid is negatively associated with albuminuria in patients with CKD. This phenomenon may help to explain the association between albuminuria and serum uric acid.

Baicalein decreases uric acid and prevents hyperuricemic nephropathy in mice

Baicalein, a natural flavonoid, is structurally advantageous for binding to xanthine oxidoreductase. In our study, molecular docking analysis and Surface Plasmon Resonance revealed a direct interaction between baicalein and xanthine oxidoreductase. Moreover, 50 mg/kg/d baicalein treatment significantly suppressed the viability of xanthine oxidoreductase in hyperuricemia mouse model. The data showed that baicalein remarkably prevented renal dysfunction, ameliorated kidney fibrosis, alleviated epithelial-mesenchymal transition and oxidative stress in hyperuricemia mice. Thus, we concluded that baicalein executed a kidney-protection action in hyperuricemia and therefore may be used as a therapeutic alternative for hyperuricemic nephropathy.

Impaired Na+-K+-ATPase signaling in renal proximal tubule contributes to hyperuricemia-induced renal tubular injury

Hyperuricemia contributes to renal inflammation. We aimed to investigate the role of Na⁺–K⁺–ATPase (NKA) in hyperuricemia-induced renal tubular injury. Human primary proximal tubular epithelial cells (PTECs) were incubated with uric acid (UA) at increasing doses or for increasing lengths of time. PTECs were then stimulated by pre-incubation with an NKA α1 expression vector or small interfering RNA before UA (100 μg ml⁻¹, 48 h) stimulation. Hyperuricemic rats were induced by gastric oxonic acid and treated with febuxostat (Feb). ATP levels, the activity of NKA and expression of its α1 subunit, Src, NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and interleukin 1β (IL-1β) were measured both in vitro and in vivo. Beginning at concentrations of 100 μg ml⁻¹, UA started to dose-dependently reduce NKA activity. UA at a concentration of 100 μg ml⁻¹ time-dependently affected the NKA activity, with the maximal increased NKA activity at 24 h, but the activity started to decrease after 48 h. This inhibitory effect of UA on NKA activity at 48 h was in addition to a decrease in NKA α1 expression in the cell membrane, but an increase in lysosomes. This process also involved the subsequent activation of Src kinase and NLRP3, promoting IL-1β processing. In hyperuricemic rats, renal cortex NKA activity and its α1 expression were upregulated at the 7th week and both decreased at the 10th week, accompanied with increased renal cortex expression of Src, NLRP3 and IL-1β. The UA levels were reduced and renal tubular injuries in hyperuricemic rats were alleviated in the Feb group. Our data suggested that the impairment of NKA and its consequent regulation of Src, NLRP3 and IL-1β in the renal proximal tubule contributed to hyperuricemia-induced renal tubular injury.

Determination of lesinurad in rat plasma by a UHPLC-MS/MS assay

Lesinurad is an oral inhibitor of urate-anion exchanger transporter 1 and has been approved by the US Food and Drug Administration for combination therapy with a xanthine oxidase inhibitor for the treatment of hyperuricemia associated with refractory gout. In the present study, a sensitive and specific ultra high-performance liquid chromatography with tandem mass spectrometry assay was established and verified for the determination of lesinurad in rat plasma and was described in details for the first time. Chromatographic separation of lesinurad and diazepam (internal standard, IS) was performed on a Rapid Resolution HT C18 column (3.0 × 100 mm, 1.8 µm) using methanol–water (70:30, v/v) as the mobile phase at a flow rate of 0.3 mL/min. Lesinurad and IS were extracted from plasma by liquid–liquid extraction using ethyl acetate. The mass spectrometric detection was carried out using an electrospray ionization source in positive mode. Multiple reaction monitoring was used for quantification of the precursor to product ion at m/z 405.6 → 220.9 for lesinurad and m/z 285.1 → 192.8 for IS. The assay was well validated for selectivity, accuracy, precision, recovery, linearity, matrix effects, and stability. The verified method was applied to obtain the pharmacokinetic parameters and concentration–time profiles for lesinurad after oral/intravenous administration in rats. The study might provide an important reference and a necessary complement for the qualitative and quantitative evaluation of lesinurad.

Emodinol ameliorates urate nephropathy by regulating renal organic ion transporters and inhibiting immune inflammatory responses in rats

Emodinol, 1β, 3β, 23-trihydroxyolean-12-en-28-acid, as the main active ingredient firstly extracted from the rhizomes of Elaeagus pungens by our Research Group, was identified with apparent uricosuric and nephroprotective effects in hyperuricemia mice in our previous study. This study aimed to investigate the renal protective effect of emodinol in urate nephropathy rats. Rats were orally administrated by combined adenine and ethambutol to induce urate nephropathy. Emodinol at various doses were administered intragastrically to urate nephropathy rats daily. Serum uric acid (Sur), serum creatinine (Scr) and blood urea nitrogen (BUN) levels, as well as Interleukin-1beta (IL-1β) and tumor necrosis factor- alpha (TNF-α) concentrations in serum and kidney were determined. Renal protein expressions of organic ion transporters, components of NLR pyrin domain containing 3 (NLRP3) inflammasome, as well as key factors involved in toll-like receptors (TLRs)/myeloid differentiation factor 88 (MyD88)/nuclear factor kappa B (NF-κB) signaling pathway were analyzed by western blot. Emodinol significantly decreased Sur, Scr and BUN levels in adenine and ethambutol - induced urate nephropathy rats. More importantly, emodinol reversed dys-expression of organic ion transporters, inhibited NLRP3 inflammsome activation and suppressed TLRs/MyD88/NF-κB signaling pathway in the kidneys of urate nephropathy rats. Consistently, dilated tubules and tubular UA crystal formation, as well as tubular interstitial inflammatory cells infiltration in kidneys of urate nephropathy rats were obviously attenuated by emodinol, accompanied by restored renal and serum inflammatory cytokines concentrations. Taken together, the date suggested that emodinol ameliorated urate nephropathy by regulating renal organic ion transporters and inhibiting immune inflammatory responses in rats.

The influence of serum uric acid on renal function in patients with calcium or uric acid stone: A population-based analysis

OBJECTIVES

To determine the influence of serum uric acid (UA) levels on renal impairment in patients with UA stone.

MATERIALS AND METHODS

We retrospectively analyzed 463 patients with calcium oxalate and/or calcium phosphate stones (CaOx/CaP), and 139 patients with UA stones. The subjects were divided into the serum UA-high (UA ≥ 7.0 mg/dL) or the UA-low group (UA < 7.0 mg/dL). The control group comprised 3082 community-dwelling individuals that were pair-matched according to age, sex, body mass index, comorbidities, hemoglobin, serum albumin, and serum UA using propensity score matching. We compared renal function between controls and patients with UA stone (analysis 1), and between patients with CaOx/CaP and with UA stone (analysis 2). Logistic regression analysis was used to evaluate the impact of the hyperuricemia on the development of stage 3 and 3B chronic kidney disease (CKD) (analysis 3).

RESULTS

The renal function was significantly associated with serum UA levels in the controls and patients with CaOx/CaP and UA stones. In pair-matched subgroups, patients with UA stone had significantly lower renal function than the control subjects (analysis 1) and patients with CaOx/CaP stones (analysis 2) regardless of hyperuricemia. Multivariate logistic regression analysis revealed that patients with UA stone, CaOx/CaP, hyperuricemia, presence of cardiovascular disease, higher body mass index, older age and lower hemoglobin had significantly higher risk of stage 3 and 3B CKD (analysis 3).

CONCLUSION

Patients with UA stones had significantly worse renal function than controls and CaOx/CaP patients regardless of hyperuricemia. Urolithiasis (CaOx/CaP and UA stone) and hyperuricemia had an association with impaired renal function. Our findings encourage clinicians to initiate intensive treatment and education approaches in patients with urolithiasis and/or hyperuricemia in order to prevent the progression of renal impairment.

Hyperuricaemia and risk of nonalcoholic fatty liver disease: A meta-analysis

BACKGROUND

The association between hyperuricaemia and nonalcoholic fatty liver disease (NAFLD), one of the leading causes of cirrhosis worldwide, has been demonstrated in recent epidemiological studies. This meta-analysis was conducted to summarize all available data and to estimate the risk of NAFLD among subjects with hyperuricaemia.

METHODS

Comprehensive literature review was conducted using MEDLINE and EMBASE database through August 2016 to identify studies that compared the risk of NAFLD among subjects with hyperuricaemia vs those with normal uric acid level. Effect estimates from individual study were extracted and combined together using random-effect, generic inverse variance method of DerSimonian and Laird.

RESULTS

Twenty-five studies met the eligibility criteria and were included in the meta-analysis. The risk of NAFLD in subjects with hyperuricaemia was significantly higher than subjects with normal uric acid level with the pooled odds ratio (OR) of 1.97 (95% confidence interval (CI), 1.69-2.29). The heterogeneity between studies of the overall analysis was high with an I² of 87%. Subgroup analysis based on 11 studies that provided data on males subgroup and nine studies that provided data on females subgroup showed that the risk was significantly increased for both sexes with pooled OR of 1.64 (95% CI, 1.40-1.93) among males and pooled OR of 2.21 (95% CI, 1.85-2.64) among females.

CONCLUSIONS

A significantly increased risk of NAFLD among patients with hyperuricaemia was demonstrated in this meta-analysis. Further studies are required to establish the role of uric acid in the pathogenesis of NAFLD.

Development of Nephrolithiasis in Asymptomatic Hyperuricemia: A Cohort Study

BACKGROUND

Although the association between gout and nephrolithiasis is well known, the relationship between asymptomatic hyperuricemia and the development of nephrolithiasis is largely unknown.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

239,331 Korean adults who underwent a health checkup examination during January 2002 to December 2014 and were followed up annually or biennially through December 2014.

PREDICTOR

Baseline serum uric acid levels of participants.

OUTCOME

The development of nephrolithiasis during follow-up.

MEASUREMENTS

Nephrolithiasis is determined based on ultrasonographic findings. A parametric Cox model was used to estimate the adjusted HRs of nephrolithiasis according to serum uric acid level.

RESULTS

During 1,184,653.8 person-years of follow-up, 18,777 participants developed nephrolithiasis (incidence rate, 1.6/100 person-years). Elevated uric acid level was significantly associated with increased risk for nephrolithiasis in a dose-response manner (P for trend < 0.001) in men. This dose-response association was not observed in women. In male participants, multivariable-adjusted HRs for incident nephrolithiasis comparing uric acid levels of 6.0 to 6.9, 7.0 to 7.9, 8.0 to 8.9, 9.0 to 9.9, and ≥10.0mg/dL with uric acid levels < 6.0mg/dL were 1.06 (95% CI, 1.02-1.11), 1.11 (95% CI, 1.05-1.16), 1.21 (95% CI, 1.13-1.29), 1.31 (95% CI, 1.17-1.46), and 1.72 (95% CI, 1.44-2.06), respectively. This association was observed in all clinically relevant subgroups and persisted even after adjustment for homeostasis model assessment of insulin resistance and high-sensitivity C-reactive protein level.

LIMITATIONS

Dietary information and computed tomographic diagnosis of nephrolithiasis were unavailable.

CONCLUSIONS

In this large cohort study, increased serum uric acid level was modestly and independently associated with increased risk for the development of nephrolithiasis in a dose-response manner in apparently healthy men.

Inflammatory status and uricaemia determine HDL-cholesterol levels in hypertensive adults over 65: an analysis of the FAPRES register

In inflammatory disease, the levels of high-density lipoprotein cholesterol (HDL-C) decrease, and the composition of HLD-C changes. Data from the "non-inflammatory" general population indicate the presence of the same phenomenon, albeit to a smaller extent. Levels of uricaemia contribute to the overall inflammatory state of patients. The aim of this study was to analyse the association between inflammatory state, levels of uricaemia, and levels of HLD-C in a hypertensive Spanish population aged 65 or older. This was a retrospective analysis of the FAPRES database. We compared lipid levels [HDL-C, low-density lipoprotein cholesterol (LDL-C), total cholesterol, and triglycerides] in terciles of patients according to their leukocyte counts and uricaemia. When we observed statistically significant differences at a 95% confidence level, we constructed a multivariable linear regression model to adjust for possible confounders. We analysed 860 patients (52.7% women) with a mean age of 72.9 years (±5.8). Participants in the highest tercile for leukocytes or uricaemia presented with significantly lower levels of HDL-C and higher levels of triglycerides, but there was no difference in total cholesterol or LDL-C. The multivariable analysis confirmed an independent and inverse association between HDL-C and both leukocytes (β = -0.001, p = 0.025) and uricaemia (β = -1.054, p = 0037) as well as an independent, direct association between triglycerides and both leukocytes (β = 0.004, p = 0.049), and uricaemia (β = 8.411, p = 0.003). In hypertensive adults aged 65 or older, inflammatory state, and uricaemia independently operate to decrease HDL-C-these findings confirm those described in studies in people with inflammatory disease. This phenomenon could help to define a proatherogenic profile in people without inflammatory disease.

Physiological functions and pathogenic potential of uric acid: A review

Uric acid is synthesized mainly in the liver, intestines and the vascular endothelium as the end product of an exogenous pool of purines, and endogenously from damaged, dying and dead cells, whereby nucleic acids, adenine and guanine, are degraded into uric acid. Mentioning uric acid generates dread because it is the established etiological agent of the severe, acute and chronic inflammatory arthritis, gout and is implicated in the initiation and progress of the metabolic syndrome. Yet, uric acid is the predominant anti-oxidant molecule in plasma and is necessary and sufficient for induction of type 2 immune responses. These properties may explain its protective potential in neurological and infectious diseases, mainly schistosomiasis. The pivotal protective potential of uric acid against blood-borne pathogens and neurological and autoimmune diseases is yet to be established.