Direct radical scavenging activity of benzbromarone provides beneficial antioxidant properties for hyperuricemia treatment

Hyperuricemia and its related diseases: mechanisms and advances in therapy

Hyperuricemia, characterized by elevated levels of serum uric acid (SUA), is linked to a spectrum of commodities such as gout, cardiovascular diseases, renal disorders, metabolic syndrome, and diabetes, etc. Significantly impairing the quality of life for those affected, the prevalence of hyperuricemia is an upward trend globally, especially in most developed countries. UA possesses a multifaceted role, such as antioxidant, pro-oxidative, pro-inflammatory, nitric oxide modulating, anti-aging, and immune effects, which are significant in both physiological and pathological contexts. The equilibrium of circulating urate levels hinges on the interplay between production and excretion, a delicate balance orchestrated by urate transporter functions across various epithelial tissues and cell types. While existing research has identified hyperuricemia involvement in numerous biological processes and signaling pathways, the precise mechanisms connecting elevated UA levels to disease etiology remain to be fully elucidated. In addition, the influence of genetic susceptibilities and environmental determinants on hyperuricemia calls for a detailed and nuanced examination. This review compiles data from global epidemiological studies and clinical practices, exploring the physiological processes and the genetic foundations of urate transporters in depth. Furthermore, we uncover the complex mechanisms by which the UA induced inflammation influences metabolic processes in individuals with hyperuricemia and the association with its relative disease, offering a foundation for innovative therapeutic approaches and advanced pharmacological strategies.

Uncovering the Potential Mechanisms and Effects of Hyperuricemia and its Associated Diseases on Male Reproduction

Male fertility and metabolic disorders, including obesity and diabetes, are closely connected. Since hyperuricemia and metabolic syndrome are strongly related, male fertility and hyperuricemia may, to some degree, be associated. According to recent studies, hyperuricemia imposes various effects on sex hormones, semen quality, and male erectile dysfunction. Some researchers claim that uric acid worsens male semen and raises the risk of erectile dysfunction (ED), while others state that it safeguards both penile erection and male semen. Additionally, it has been shown that gout and metabolic syndrome also raise the risk of ED. To clarify this controversy, the influence and potential mechanisms of hyperuricemia on ED, semen quality, sex hormone levels, and the effects of hyperuricemia-related disorders on ED will be comprehensively summarized.

Aqueous extract of Phellinus igniarius ameliorates hyperuricemia and renal injury in adenine/potassium oxonate-treated mice

Phellinus igniarius is an important medicinal and edible fungus with diverse biological activities. This study aimed to investigate the effects of aqueous extract from P. igniarius (API) on the treatment of hyperuricemia (HUA) and related kidney damage. The chemical constituents of API were determined. The therapeutic effects of API on HUA and renal injury were assessed in adenine/potassium oxonate (PO)-treated mice. The constituent analysis of API revealed a predominance of polysaccharides (33.4 %), followed by total flavonoids (9.1 %), and total triterpenoids (3.5 %). Compared to control, the adenine/PO treatment greatly elevated serum uric acid (UA) levels but this elevation was attenuated by API. In the liver, the expression and activity of xanthine oxidase (XOD) were increased by HUA which were diminished by API. Furthermore, API was found to enhance the expression of UA transporter ABCG2 in the kidney and intestine of HUA mice, suggesting elevating UA excretion. Additionally, API ameliorated HUA-induced renal injury, as indicated by reduced serum BUN/creatinine levels, decreased glomerular and tubular damage, and lowered fibrotic levels. Network pharmacology analysis predicted that P. igniarius may regulate mitochondrial function to improve HUA-related renal injury. This prediction was then substantialized by the API-induced upregulation of NAD+/NADH ratio, ATP level, SOD2 activity, and expression of SOD2/PCG-1α/PPARγ in the kidney of HUA mice. Our results demonstrate that API may effectively ameliorate HUA by reducing UA production in the liver and enhancing UA excretion in the kidney and intestine, and it might be a potential therapy to HUA-related renal injury.

Urate-lowering agents do not have clinically relevant negative effects on sperm quality and reproductive hormones in men with gout: a prospective open-label cohort study

OBJECTIVE

The objective of this study was to analyze and compare the effects of different urate-lowering agents on testicular functions in men with gout in a clinical setting.

METHODS

In this prospective cohort study (Clinical Trial Registration Number: NCT04213534), a total of 49 male patients aged 18-45 years with gout were enrolled. They were divided into three groups and received treatment with either allopurinol, febuxostat or benzbromarone for a duration of 3 months. Semen parameters, reproductive hormones and biochemical assessments were evaluated at baseline, month 1, and month 3.

RESULTS

Overall, 40 individuals (81.6%) completed the follow-up visits. In allopurinol group, there were no significant differences in semen parameters from baseline to month 3. Most of sperm parameters in febuxostat group did not show notable changes, except for a decrease in sperm motility at month 3(33.6%, [22.9-54.3] vs 48.4%, [27.4-67.6], p = 0.033). However, the total motile sperm count did not differ significantly after febuxostat treatment. Surprisingly, administration of benzbromarone resulted in improved sperm concentration (37.19 M/mL, [29.6-69.92] vs 58.5 M/mL, [49.8-116.6], p = 0.001). There were no significant changes observed in sperm DNA integrity and reproductive hormones in the three groups from baseline to month 3. The incidence of adverse events did not differ significantly among the three groups as well.

CONCLUSION

This study is the first to demonstrate that urate-lowering agents, allopurinol and febuxostat, do not have clinically relevant negative effects on sperm quality and reproductive hormones in men with gout, and benzbromarone presents improving sperm concentration. Results provide important preliminary guidance for the development of reproductive health management guidelines for patients RCID with gout.

Emerging Roles of Xanthine Oxidoreductase in Chronic Kidney Disease

Xanthine Oxidoreductase (XOR) is a ubiquitous, essential enzyme responsible for the terminal steps of purine catabolism, ultimately producing uric acid that is eliminated by the kidneys. XOR is also a physiological source of superoxide ion, hydrogen peroxide, and nitric oxide, which can function as second messengers in the activation of various physiological pathways, as well as contribute to the development and the progression of chronic conditions including kidney diseases, which are increasing in prevalence worldwide. XOR activity can promote oxidative distress, endothelial dysfunction, and inflammation through the biological effects of reactive oxygen species; nitric oxide and uric acid are the major products of XOR activity. However, the complex relationship of these reactions in disease settings has long been debated, and the environmental influences and genetics remain largely unknown. In this review, we give an overview of the biochemistry, biology, environmental, and current clinical impact of XOR in the kidney. Finally, we highlight recent genetic studies linking XOR and risk for kidney disease, igniting enthusiasm for future biomarker development and novel therapeutic approaches targeting XOR.

Targeted Metabolomics Highlights Dramatic Antioxidant Depletion, Increased Oxidative/Nitrosative Stress and Altered Purine and Pyrimidine Concentrations in Serum of Primary Myelofibrosis Patients

To date, little is known concerning the circulating levels of biochemically relevant metabolites (antioxidants, oxidative/nitrosative stress biomarkers, purines, and pyrimidines) in patients with primary myelofibrosis (PMF), a rare form of myeloproliferative tumor causing a dramatic decrease in erythropoiesis and angiogenesis. In this study, using a targeted metabolomic approach, serum samples of 22 PMF patients and of 22 control healthy donors were analyzed to quantify the circulating concentrations of hypoxanthine, xanthine, uric acid (as representative purines), uracil, β-pseudouridine, uridine (as representative pyrimidines), reduced glutathione (GSH), ascorbic acid (as two of the main water-soluble antioxidants), malondialdehyde, nitrite, nitrate (as oxidative/nitrosative stress biomarkers) and creatinine, using well-established HPLC method for their determination. Results showed that PMF patients have dramatic depletions of both ascorbic acid and GSH (37.3- and 3.81-times lower circulating concentrations, respectively, than those recorded in healthy controls, p < 0.0001), accompanied by significant increases in malondialdehyde (MDA) and nitrite + nitrate (4.73- and 1.66-times higher circulating concentrations, respectively, than those recorded in healthy controls, p < 0.0001). Additionally, PMF patients have remarkable alterations of circulating purines, pyrimidines, and creatinine, suggesting potential mitochondrial dysfunctions causing energy metabolism imbalance and consequent increases in these cell energy-related compounds. Overall, these results, besides evidencing previously unknown serum metabolic alterations in PMF patients, suggest that the determination of serum levels of the aforementioned compounds may be useful to evaluate PMF patients on hospital admission for adjunctive therapies aimed at recovering their correct antioxidant status, as well as to monitor patients' status and potential pharmacological treatments.

Attenuation of LPS-Induced Lung Injury by Benziodarone via Reactive Oxygen Species Reduction

As overproduction of reactive oxygen species (ROS) causes various diseases, antioxidants that scavenge ROS, or inhibitors that suppress excessive ROS generation, can be used as therapeutic agents. From a library of approved drugs, we screened compounds that reduced superoxide anions produced by pyocyanin-stimulated leukemia cells and identified benzbromarone. Further investigation of several of its analogues showed that benziodarone possessed the highest activity in reducing superoxide anions without causing cytotoxicity. In contrast, in a cell-free assay, benziodarone induced only a minimal decrease in superoxide anion levels generated by xanthine oxidase. These results suggest that benziodarone is an inhibitor of NADPH oxidases in the plasma membrane but is not a superoxide anion scavenger. We investigated the preventive effect of benziodarone on lipopolysaccharide (LPS)-induced murine lung injury as a model of acute respiratory distress syndrome (ARDS). Intratracheal administration of benziodarone attenuated tissue damage and inflammation via its ROS-reducing activity. These results indicate the potential application of benziodarone as a therapeutic agent against diseases caused by ROS overproduction.

Cardiovascular risk associated with allopurinol or benzbromarone treatment in patients with gout

Background:

In previous studies, cardiovascular (CV) risk was increased in patients with gout. The effects of uric acid–lowering therapy on CV risk in gout patients have been investigated in numerous studies; however, allopurinol and benzbromarone have rarely been compared.

Objectives:

To compare CV risk based on allopurinol and benzbromarone treatment in Korean gout patients.

Design:

A nationwide population-based retrospective cohort study.

Methods:

We used South Korea database of the Health Insurance Review and Assessment (HIRA) service to identify gout patients ⩾18 years of age who newly started allopurinol or benzbromarone between 2009 and 2015. The primary outcome of the study was the occurrence of a composite CV endpoint, which included coronary revascularization, hospitalization due to myocardial infarction, ischemic stroke, and transient ischemic attack. Cox proportional hazard regression analysis and Kaplan–Meier curves were used for analysis.

Results:

The study included 257,097 allopurinol initiators and 7868 benzbromarone initiators. Compared with allopurinol initiators, the adjusted hazard ratio (aHR) of the composite CV endpoint of benzbromarone initiators was 1.01 [95% confidence interval (CI): 0.83−1.21], which was not significantly different. The results did not change even when 1:3 propensity score matching was performed for baseline characteristics. In subgroup analysis of high-risk patients with CV disease, significant difference was not observed between allopurinol and benzbromarone initiators.

Conclusion:

In this study, significant difference was not found in CV risk between allopurinol and benzbromarone initiators. In the high-CV-risk group, the incidence of CV events did not differ between allopurinol and benzbromarone initiators.

Prognostic value of hyperuricemia for patients with sepsis in the intensive care unit

This study evaluated the relationship between hyperuricemia at admission and the clinical prognosis of patients with sepsis. The data were obtained from the Intensive Care Medical Information Database III. The patients were divided into a normal serum uric acid group and a hyperuricemia group. The main outcome was 90-day mortality, and the secondary outcomes were hospital mortality, 30-day mortality, and acute kidney injury. Propensity score matching was used to balance the baseline characteristics of the groups. Our study retrospectively included 954 patients. Before and after propensity score matching, the incidence of AKI, the 30-day and 90-day mortality rates were significantly higher in the hyperuricemia group. Cox regression analysis showed that hyperuricemia was significantly associated with 90-day mortality (HR 1.648, 95% CI 1.215–2.234, p = 0.006), and hyperuricemia was significantly associated with the incidence of AKI (HR 1.773, 95% CI 1.107–2.841, p = 0.017). The Kaplan–Meier survival curve showed that the 90-day survival rate was significantly lower in the hyperuricemia group. In patients with sepsis in the intensive care unit, hyperuricemia was significantly associated with increased risk 90-day all-cause mortality and the incidence of AKI.

Cardiovascular risk associated with allopurinol vs. benzbromarone in patients with gout

Aims 

With the high prevalence of gout and associated cardiovascular (CV) diseases, information on the comparative CV safety of individual urate-lowering drugs becomes increasingly important. However, few studies examined the CV risk of uricosuric agents. We compared CV risk among patients with gout who initiated allopurinol vs. benzbromarone.

Methods and results 

Using the Korean National Health Insurance claims data (2002–17), we conducted a cohort study of 124 434 gout patients who initiated either allopurinol (n = 103 695) or benzbromarone (n = 20 739), matched on propensity score at a 5:1 ratio. The primary outcome was a composite CV endpoint of myocardial infarction, stroke/transient ischaemic attack, or coronary revascularization. To account for competing risk of death, we used cause-specific hazard models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the outcomes comparing allopurinol initiators with benzbromarone. Over a mean follow-up of 1.16 years, 2258 patients developed a composite CV event. The incidence rate of the composite CV event was higher in allopurinol initiators (1.81 per 100 person-years) than benzbromarone (1.61 per 100 person-years) with a HR of 1.22 (95% CI 1.05–1.41). The HR for all-cause mortality was 1.66 (95% CI 1.43–1.93) among allopurinol initiators compared with benzbromarone.

Conclusion 

In this large population-based cohort of gout patients, allopurinol was associated with an increased risk of composite CV events and all-cause mortality compared to benzbromarone. Benzbromarone may reduce CV risk and mortality in patients with gout, although more studies are necessary to confirm our findings and to advance our understanding of the underlying mechanisms.

The Impact of Urate-Lowering Therapy in Post-Myocardial Infarction Patients: Insights from a Population-Based, Propensity Score-Matched Analysis

The role of urate‐lowering therapy (ULT) for the primary prevention of cardiovascular (CV) events has been widely discussed, but its evidence for the secondary prevention of myocardial infarction (MI) is limited. Therefore, we conduct a population‐based, propensity score‐matched cohort study to investigate the CV outcomes among patients with post‐MI with and without ULT. A total of 19,042 newly diagnosed in‐hospital patients with MI were selected using the Taiwan National Health Insurance Database between January 1, 2005, and December 31, 2016. After 1:1 propensity score matching with covariates, patients with MI with (n = 963) and without (n = 963) ULT were selected for further analysis. The primary outcome was the all‐cause mortality and the secondary outcomes were composite CV outcomes, including hospitalization for recurrent MI, stroke, heart failure, and cardiac arrhythmias. ULT users were associated with lower all‐cause mortality (adjusted hazard ratio (adjHR), 0.67; 95% confidence interval (CI), 0.51–0.87) compared to the ULT nonusers. In addition, ULT users had a significantly lower risk of recurrent MI, which needed revascularization by percutaneous coronary intervention or coronary artery bypass grafting (adjHR, 0.67; 95% CI, 0.53–0.86) than the ULT nonusers. The primary and secondary outcomes were not different between patients with post‐MI who received uricosuric agents and xanthine oxidase inhibitors. The anti‐inflammatory effect of ULT plays an essential role in MI management. From a real‐world setting, this study shows that ULT is associated with the lower risk of all‐cause mortality in patients with post‐MI. In addition, the result shows the possible lower incidence of repeat revascularization procedures in the ULT users.

Ameliorative effect and mechanism of Yi-Suan-Cha against hyperuricemia in rats

BACKGROUND

This study aimed to evaluate the urate-lowering effects of Yi-Suan-Cha and explore its underlying mechanisms in experimental hyperuricemia induced in rats.

METHODS

Forty-eight male SD rats were randomly allocated into normal control, model, allopurinol, benzbromarone, low-dose Yi-Suan-Cha (0.2 g/ml), and high-dose Yi-Suan-Cha (0.4 g/ml) groups (n = 8 rats per group). Rat models of hyperuricemia were established through intragastric administration of adenine 25 mg/kg + potassium oxalate 300 mg/kg for 3 weeks. After the last administration, serum uric acid, creatinine, and urea nitrogen levels were measured. Renal histopathology was observed by hematoxylin-eosin staining. Xanthine oxidase level in serum and liver homogenates was measured by ELISA. The protein and mRNA expression of URAT1, ABCG2, OAT1, and GLUT9 in the kidney was detected by Western blotting and RT-PCR, respectively.

RESULTS

The serum uric acid levels were significantly lowered in all medication groups than in the model group. The benzbromarone and both Yi-Suan-Cha groups showed clear kidney structures with no obvious abnormalities. Compared with the normal control group, the model group showed increased URAT1/GLUT9 protein expression and decreased ABCG2/OAT1 protein expression. Compared with the model group, both Yi-Suan-Cha groups showed decreased URAT1/GLUT9 protein expression and increased ABCG2/OAT1 protein expression. Compared with that in the normal control group, URAT1/GLUT9 mRNA expression increased in the model group. Compared with the model group, the low-dose and high-dose Yi-Suan-Cha groups showed decreased URAT1/GLUT9 mRNA expression and increased ABCG2/OAT1 mRNA expression.

CONCLUSION

Yi-Suan-Cha may lower uric acid level by downregulating URAT1/GLUT9 expression and upregulating ABCG2/OAT1 expression.

The Role of Oxidative Stress in Hyperuricemia and Xanthine Oxidoreductase (XOR) Inhibitors

Uric acid is the end product of purine metabolism in humans. Hyperuricemia is a metabolic disease caused by the increased formation or reduced excretion of serum uric acid (SUA). Alterations in SUA homeostasis have been linked to a number of diseases, and hyperuricemia is the major etiologic factor of gout and has been correlated with metabolic syndrome, cardiovascular disease, diabetes, hypertension, and renal disease. Oxidative stress is usually defined as an imbalance between free radicals and antioxidants in our body and is considered to be one of the main causes of cell damage and the development of disease. Studies have demonstrated that hyperuricemia is closely related to the generation of reactive oxygen species (ROS). In the human body, xanthine oxidoreductase (XOR) catalyzes the oxidative hydroxylation of hypoxanthine to xanthine to uric acid, with the accompanying production of ROS. Therefore, XOR is considered a drug target for the treatment of hyperuricemia and gout. In this review, we discuss the mechanisms of uric acid transport and the development of hyperuricemia, emphasizing the role of oxidative stress in the occurrence and development of hyperuricemia. We also summarize recent advances and new discoveries in XOR inhibitors.

Reversing cytotoxicity of uric acid by supramolecular encapsulation with acyclic cucurbit[n]uril

Supramolecular encapsulation removes harmful substances from organisms has evolved into a new strategy. In this article, we prepared three supramolecular complexes of acyclic cucurbit[n]urils (ACBs) with uric acid (UA), and studied the inclusion behaviors of ACBs and UA by fluorescence spectroscopy, UV-vis spectroscopy and nuclear magnetic resonance. Furthermore, we characterized the effect of the complexes of UA with ACBs on the expression of inflammatory biomarkers in human hepatoma HepG2 cell lines through C-reactive protein (CRP) western blot. The results showed UA molecules can be recognized by three ACBs with different binding constants, and ACBs successfully blocked the inflammatory stimulation of uric acid on HepG2 cell lines and inhibited the expression of the major inflammatory factor CRP by formations of complexes between UA and ACBs. This article proves that ACBs can efficiently reversing cytotoxicity of UA, which provides a new method to treating hyperuricemia disease.

Randomized, Open-Label, Cross-Over Comparison of the Effects of Benzbromarone and Febuxostat on Endothelial Function in Patients with Hyperuricemia

Uric acid is generated with reactive oxygen species via xanthine oxidase (XO), and hyperuricemia, which is identified as the excess of uric acid in the blood, has been associated with vascular endothelial dysfunction. However, the effects of urate-lowering medicines on endothelial function have not been fully elucidated. Thus this study determined and compared the effects of benzbromarone (urate transporter 1 inhibitor) and febuxostat (XO inhibitor) on endothelial function.This randomized, cross-over, open-label study initially recruited 30 patients with hyperuricemia. They were divided into two groups, treated initially with benzbromarone or febuxostat for three months and then were switched for the next three months. Endothelial function was defined as reactive hyperemia indexes (RHI) determined using Endo-PAT 2000 before and at three and six months after medication using the two agents. Blood levels of asymmetric dimethylarginine (ADMA) and high-molecular-weight (HMW) adiponectin were also compared. We finally analyzed data from 24 patients whose endothelial function was assessed as described above.Our findings show that levels of uric acid significantly decreased, whereas those of HMW adiponectin and the RHI have significantly increased after treatment with benzbromarone. Meanwhile, in patients administered with febuxostat, uric acid levels tended to decrease and RHI significantly decreased. Neither of the two agents altered ADMA levels. The changes in RHI (P = 0.026) and HMW adiponectin levels (P = 0.001) were found to be significantly greater in patients treated with benzbromarone than febuxostat. Changes in the levels of HMW adiponectin and of uric acid were significantly correlated (r = -0.424, P = 0.039).Benzbromarone has increased adiponectin besides reducing uric acid levels, and thus, this might confer more benefits on endothelial function than febuxostat.

Research Advances in the Mechanisms of Hyperuricemia-Induced Renal Injury

Uric acid is the end product of purine metabolism in humans, and its excessive accumulation leads to hyperuricemia and urate crystal deposition in tissues including joints and kidneys. Hyperuricemia is considered an independent risk factor for cardiovascular and renal diseases. Although the symptoms of hyperuricemia-induced renal injury have long been known, the pathophysiological molecular mechanisms are not completely understood. In this review, we focus on the research advances in the mechanisms of hyperuricemia-caused renal injury, primarily on oxidative stress, endothelial dysfunction, renal fibrosis, and inflammation. Furthermore, we discuss the progress in hyperuricemia management.

Lipoxin A4 attenuates uric acid-activated, NADPH oxidase-dependent oxidative stress by interfering with translocation of p47phox in human umbilical vein endothelial cells

LipoxinA4 (LXA4) is a well-known key mediator of endogenous anti-inflammation and of the resolution of inflammation. Considerable oxidative stress occurs during inflammation due to the generation of reactive oxidative species (ROS). Moreover, high levels of uric acid (UA) contribute to endothelial cell dysfunction, which can promote disease-related morbidity, and NADPH oxidase-derived ROS are crucial regulatory factors in these responses. However, LXA4 also has the potential to reduce oxidative stress. The aim of the present study was to examine whether LXA4 could suppress UA-induced oxidative stress in human umbilical vein endothelial cells (HUVECs) and to investigate its mechanisms of action in vitro. HUVECs were incubated with or without LXA4, followed by the addition of UA. ROS levels were then measured using 2,7-dichlorodihydrofluorescein diacetate and lucigenin-enhanced chemiluminescence was used to evaluate NADPH oxidase activity. p47phox or p22phox small interfering (si)RNA were transfected into HUVECs and protein levels of p47phox were detected using western blot analysis. LXA4 significantly inhibited UA-induced generation of ROS to the same extent as the NADPH oxidase inhibitor, diphenyleneiodonium chloride. Notably, transfection of p47phox siRNA attenuated the generation of ROS and the activation of NADPH oxidase. Cells transfected with p22phox siRNA demonstrated a significant reduction in the expression of p47phox on the membrane. Further experiments demonstrated that LXA4 interfered with the transfer of p47phox from the cytoplasm to the cell membrane. These findings suggested that LXA4 inhibited the release of NADPH oxidase derived ROS in HUVECs stimulated by UA. A potential mechanism of action underlying this effect could be LXA4-mediated suppression of NADPH oxidase activity, leading to inhibition of p47phox translocation from the cytoplasm to the cell membrane.

Association between retinol intake and hyperuricaemia in adults

OBJECTIVE

Current evidences on the association between hyperuricaemia and retinol intake remain inconsistent. Furthermore, no known studies have investigated the relationship between hyperuricaemia and retinol intake from animal food and plant food separately. This study aimed to assess the relationship between different sources of retinol intake and risk of hyperuricaemia among US adults.

DESIGN

Univariate and multivariate weighted logistic regression models and restricted cubic spline models were used to assess the associations of total, animal-derived and plant-derived retinol intakes with the risk of hyperuricaemia. Dietary retinol was measured through two 24-h dietary recall interviews. Hyperuricaemia was defined as serum uric acid level ≥7·0 and ≥6·0 mg/dl in men and women, respectively.

SETTING

Data from the National Health and Nutrition Examination Survey 2009-2014 were used in this cross-sectional study.

PARTICIPANTS

Overall, 12 869 participants aged ≥20 years were included.

RESULTS

Compared with the lowest quintile, the multivariable OR of hyperuricaemia for the highest quintile intake of total, animal-derived and plant-derived retinol were 0·71 (95 % CI 0·52, 0·96), 0·76 (95 % CI 0·59, 0·96) and 0·92 (95 % CI 0·72, 1·17), respectively. The inverse association between dietary intake of total retinol and the risk of hyperuricaemia was observed in men. Dose-response analyses revealed a novel linear trend between the risk of hyperuricaemia and total, animal-derived retinol intake separately.

CONCLUSIONS

Our findings indicated that intakes of total and animal-derived retinol were negatively associated with hyperuricaemia in US adults.

Benzbromarone mitigates cisplatin nephrotoxicity involving enhanced peroxisome proliferator-activated receptor-alpha (PPAR-α) expression

AIM

Despite the great efficacy reported for cisplatin as a widely used chemotherapeutic agent, its clinical use is limited by the challenge of facing its serious side effect; nephrotoxicity. In this study, the effect of the benzbromarone on peroxisome proliferator-activated receptor-alpha (PPAR-α) was investigated against cisplatin nephrotoxicity.

MAIN METHODS

Rats were administered benzbromarone (10 mg/kg/day; p.o.) for 14 days, and cisplatin (6.5 mg/kg; i.p.) as a single dose on the 10th day. Blood and kidney tissue samples were collected for determination of kidney function, biochemical and molecular markers, as well as histopathological investigation.

KEY FINDINGS

Benzbromarone improved kidney function, that was evidenced by reduced serum creatinine and blood urea nitrogen to nearly the half, compared to the group administered cisplatin alone. The protein expression of PPAR-α was enhanced with benzbromarone treatment, along with a considerable suppression of oxidative stress as benzbromarone reduced mRNA expression of NADPH oxidase, while increased the anti-oxidant HO-1 protein expression associated with enhancing Nrf2. Besides, it displayed a marked anti-inflammatory effect involved suppression of p38 MAPK/NF-κB p65 signaling pathway and its downstream targets. Moreover, benzbromarone retarded apoptosis associated with reducing the pro-apoptotic (Bax) and enhancing the anti-apoptotic (Bcl-2) protein expressions. The protective effects of benzbromarone were also confirmed by histopathological results.

SIGNIFICANCE

Our data confirm the relation between PPAR-α, and the deleterious effects induced by cisplatin. It can also be suggested that enhancing PPAR-α expression by benzbromarone is a promising therapeutic approach that overcomes cisplatin nephrotoxicity, involving regulation of different signaling pathways: Nrf2/HO-1, p38 MAPK/NF-κB p65, and Bax/Bcl-2.

Comparative effectiveness of allopurinol, febuxostat and benzbromarone on renal function in chronic kidney disease patients with hyperuricemia: a 13-year inception cohort study

Background

Direct comparisons of the effectiveness of allopurinol with that of other urate-lowering agents in chronic kidney disease (CKD) populations, as well as guideline recommendations for clinical practice, are lacking.

Methods

We constructed a pharmacoepidemiology cohort study by including patients from Taiwan's long-term integrated CKD care program to compare the effectiveness among allopurinol, febuxostat and benzbromarone in reducing the risk of progression to dialysis. A total of 874 patients with hyperuricemia who were newly treated with allopurinol, febuxostat or benzbromarone were included. The primary and secondary outcomes were incident end-stage renal disease (ESRD) and the serum uric acid (SUA) changes from baseline, respectively. The results were analyzed using multiple Cox proportional models adjusted for multinomial propensity scores. For subgroup analyses, we further stratified patients according to whether their latest SUA level reached the therapeutic target.

Results

Compared with allopurinol, benzbromarone therapy was associated with a reduced risk of progression to dialysis, the adjusted hazard ratio was 0.50 (95% confidence interval, 0.25-0.99). Patients who received allopurinol or febuxostat exhibited a comparable risk of ESRD [adjusted hazard ratio, 0.99 (0.40-2.44)]. Febuxostat was significantly more potent than allopurinol or benzbromarone in lowering SUA levels in the fully adjusted model. Among patients who reached the therapeutic target, those with febuxostat and benzbromarone initiation had a significantly lower risk of ESRD.

Conclusions

In conclusion, compared with conventional allopurinol, febuxostat and benzbromarone may be more effective in reducing the risk of progression to dialysis and in lowering SUA levels in CKD populations.

Uric acid level changes after bariatric surgery in obese subjects with type 2 diabetes mellitus

Background

The purpose of the study was to investigate the incidence of hyperuricemia (HU) in obese subjects with type 2 diabetes mellitus (T2DM) before and after Roux-en-Y gastric bypass (RYGB), to describe the impact of this therapy in reducing uric acid levels, and its possible mechanism. This study was performed by cooperation with the First affiliated hospital of Soochow University and the Sixth People's Hospital Affiliated to Shanghai Jiao Tong University, department of general surgery.

Methods

A retrospective study was performed. From February 2015 to December 2017, we evaluated 147 obese patients with T2DM. Blood samples and other clinical data were drawn before and postoperative (1, 3, 6, 12 months after RYGB). All obese patients with T2DM underwent laparoscopic Roux-en-Y gastric bypass surgery (LRYGB). Different gender with HU were compared before and after surgery.

Results

A total of 147 patients received LRYGB (75 were female, 72 were male), and 48 patients with HU (22 were female, 26 were male). Four women and 2 men were lost to follow-up, they were excepted from this study. No patients with HU lost to follow-up. There's an intuitive downward trend about uric acid levels both in men and women, with men from 497.9 µmol/L before surgery to 371.5 µmol/L 1 year after surgery, P=0.000; women from 432.3 to 354.1 µmol/L, P=0.002. The proportion of HU changed with men from 37.1% (26/70) before surgery to 12.9% (9/70) one year after surgery, women from 31.0% (22/71) to 14.1% (10/71). The results of binary logistic regression analysis confirmed that triglycerides were clinical predictors for HU remission (P=0.004). No major late surgical complications were reported.

Conclusions

Our data showed that, bariatric surgery was effective to decrease the levels of serum uric acid (SUA) in obese patients with T2DM. Compared with traditional drug treatment, this shows a possible treatment of HU by RYGB. The remission of HU was associated with the decreased triglyceride levels in obese patients with T2DM, independent of BMI. The potential role of triglycerides in the remission of HU merits further study.

Compounds with capacity to quench the tyrosyl radical in Pseudomonas aeruginosa ribonucleotide reductase

Ribonucleotide reductase (RNR) has been extensively probed as a target enzyme in the search for selective antibiotics. Here we report on the mechanism of inhibition of nine compounds, serving as representative examples of three different inhibitor classes previously identified by us to efficiently inhibit RNR. The interaction between the inhibitors and Pseudomonas aeruginosa RNR was elucidated using a combination of electron paramagnetic resonance spectroscopy and thermal shift analysis. All nine inhibitors were found to efficiently quench the tyrosyl radical present in RNR, required for catalysis. Three different mechanisms of radical quenching were identified, and shown to depend on reduction potential of the assay solution and quaternary structure of the protein complex. These results form a good foundation for further development of P. aeruginosa selective antibiotics. Moreover, this study underscores the complex nature of RNR inhibition and the need for detailed spectroscopic studies to unravel the mechanism of RNR inhibitors.

Benzbromarone Attenuates Oxidative Stress in Angiotensin II- and Salt-Induced Hypertensive Model Rats

Oxidative stress induced by hyperuricemia is closely associated with the renin-angiotensin system, as well as the onset and progression of cardiovascular disease (CVD) and chronic kidney disease (CKD). It is therefore important to reduce oxidative stress to treat hyperuricemia. We previously found that benzbromarone, a uricosuric agent, has a direct free radical scavenging effect in vitro. The antioxidant effects of benzbromarone were evaluated in vivo via oral administration of benzbromarone for 4 weeks to model rats with angiotensin II- and salt-induced hypertension. Benzbromarone did not alter plasma uric acid levels or blood pressure but significantly reduced the levels of advanced oxidation protein products, which are oxidative stress markers. Furthermore, dihydroethidium staining of the kidney revealed a reduction in oxidative stress after benzbromarone administration. These results suggest that benzbromarone has a direct antioxidant effect in vivo and great potential to prevent CVD and CKD.

Association between Dietary Zinc Intake and Hyperuricemia among Adults in the United States

We aim to explore the associations between dietary zinc intake and hyperuricemia (HU) in United States (US) adults. 24,975 US adults aged 20 years or older from the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2014 were stratified into quintiles based on zinc intake. All dietary intake measured through 24-h dietary recalls. Multivariable logistic regression analysis was performed to examine the association between zinc intake and HU after adjustment for possible confounders. For males, compared with respondents consuming less than 7.33 mg zinc daily, the adjusted odds ratios (ORs) were 0.83 (95% CI, 0.71, 0.97) among those consuming 10.26–13.54 mg zinc daily, 0.78 (95% CI, 0.63–0.96) among those consuming 18.50 mg or greater, and p for the trend was 0.0134. For females, compared with respondents consuming less than 5.38 mg zinc daily, the OR was 0.78 (95% CI, 0.63, 0.97) among those consuming 9.64–12.93 mg zinc daily, and p for the trend was 0.3024. Our findings indicated that dietary zinc intake is inversely associated with HU in US men and women, independent of some major confounding factors.

Podocyte Injury and Albuminuria in Experimental Hyperuricemic Model Rats

Although hyperuricemia is shown to accelerate chronic kidney disease, the mechanisms remain unclear. Accumulating studies also indicate that uric acid has both pro- and antioxidant properties. We postulated that hyperuricemia impairs the function of glomerular podocytes, resulting in albuminuria. Hyperuricemic model was induced by oral administration of 2% oxonic acid, a uricase inhibitor. Oxonic acid caused a twofold increase in serum uric acid levels at 8 weeks when compared to control animals. Hyperuricemia in this model was associated with the increase in blood pressure and the wall-thickening of afferent arterioles as well as arcuate arteries. Notably, hyperuricemic rats showed significant albuminuria, and the podocyte injury marker, desmin, was upregulated in the glomeruli. Conversely, podocin, the key component of podocyte slit diaphragm, was downregulated. Structural analysis using transmission electron microscopy confirmed podocyte injury in this model. We found that urinary 8-hydroxy-2'-deoxyguanosine levels were significantly increased and correlated with albuminuria and podocytopathy. Interestingly, although the superoxide dismutase mimetic, tempol, ameliorated the vascular changes and the hypertension, it failed to reduce albuminuria, suggesting that vascular remodeling and podocyte injury in this model are mediated through different mechanisms. In conclusion, vasculopathy and podocytopathy may distinctly contribute to the kidney injury in a hyperuricemic state.

Association between low dietary zinc and hyperuricaemia in middle-aged and older males in China: a cross-sectional study

OBJECTIVE

To examine the associations between dietary zinc intake and hyperuricaemia.

DESIGN

Cross-sectional study.

SETTING

This study was conducted in a health examination centre of China.

PARTICIPANTS

A total of 5168 middle-aged and older participants (aged 40 years or above) (2697 men and 2471 women) were included.

OUTCOME MEASURES

Dietary zinc intake was assessed using a validated semiquantitative food frequency questionnaire. Hyperuricaemia was defined as uric acid ≥416 µmol/L for males and ≥360 µmol/L for females.

RESULTS

For males, the prevalence of hyperuricaemia was 22.9%. After adjusting for age, body mass index (BMI) and energy intake, the ORs were 0.68 (95% CI 0.45 to 0.92) in the second quintile, 0.63 (95% CI 0.45 to 0.89) in the third quintile, 0.68 (95% CI 0.46 to 1.00) in the fourth quintile and 0.55 (95% CI 0.35 to 0.87) in the fifth quintile comparing the lowest quintile of Zn intake, respectively (p for trend=0.03). In the multivariable adjusted model, the relative odds of hyperuricaemia were significantly decreased by 0.71 times in the second quintile of zinc intake (OR 0.71, 95% CI 0.52 to 0.98), 0.64 times in the third quintile (OR 0.65, 95% CI 0.44 to 0.94) and 0.55 times in the fifth quintile (OR 0.56, 95% CI 0.32 to 0.97) compared with those in the lowest quintile, and p for trend was 0.064. For females, the prevalence of hyperuricaemia was 10.0%, and unadjusted, minimally adjusted as well as multivariable adjusted ORs all suggested no significant association between dietary zinc intake and hyperuricaemia.

CONCLUSIONS

The findings of this cross-sectional study indicated that dietary zinc intake was inversely associated with hyperuricaemia in middle-aged and older males, but not in females. The association was significant after considering the influence of age, BMI and energy intake, and after that, minimum adjustment remained independent of further confounding factors such as vitamin C intake, alcohol drinking status and nutrient supplementation.