Physiology of Hyperuricemia and Urate-Lowering Treatments

Hypouricemic, hepatoprotective and nephroprotective roles of oligopeptides derived from Auxis thazard protein in hyperuricemic mice

The oligopeptides derived from Auxis thazard protein (ATO) are a class of small peptides with molecular weight <1 kDa and good bioactivity. This paper aimed to explore the hypouricemic, hepatoprotective, and nephroprotective effects of ATO and its potential mechanisms in hyperuricemia in mice induced by potassium oxonate. The results showed that ATO significantly reduced serum UA, serum creatinine levels, inhibited XOD and ADA activities in the liver (p < 0.05), and accelerated UA excretion by downregulating the gene expression of renal mURAT1 and mGLUT9 and upregulating the gene expression of mABCG2 and mOAT1. ATO could also reduce the levels of liver MDA, increase the activities of SOD and CAT, and reduce the levels of IL-1β, MCP-1 and TNF-α. Histological analysis also showed that ATO possessed hepatoprotective and nephroprotective activities in hyperuricemic mice. Thus, ATO could reduce the serum UA level in hyperuricemic mice by decreasing UA production and promoting UA excretion from the kidney, suggesting that ATO could be developed as a dietary supplement for hyperuricemia treatment.

Saengmaeksan, a traditional herbal formulation consisting of Panax ginseng, ameliorates hyperuricemia by inhibiting xanthine oxidase activity and enhancing urate excretion in rats

Background

Saengmaeksan (SMS) is a traditional Korean medicine composed of three herbs, Panax ginseng, Schisandra chinensis, and Liriope platyphylla. SMS is used to treat respiratory and cardiovascular disorders. However, whether SMS exerts antihyperuricemic effects is unknown.

Methods

Effects of the SMS extract in water (SMS-W) and 30% ethanol (SMS-E) were studied in a rat model of potassium oxonate-induced hyperuricemia. Uric acid concentrations and xanthine oxidase (XO) activities were evaluated in the serum, urine, and hepatic tissue. Using renal histopathology to assess kidney function and uric acid excretion, we investigated serum creatinine and blood urea nitrogen concentrations, as well as protein levels of renal urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), and organic anion transporter 1 (OAT1). The effects of SMS on in vitro XO activity and uric acid uptake were also evaluated. The components of SMS were identified using Ultra Performance Liquid Chromatography (UPLC).

Results

SMS-E reduced serum uric acid and creatinine concentrations, and elevated urine uric acid excretion. SMS-E lowered XO activities in both the serum and liver, and downregulated the expression of renal URAT1 and GLUT9 proteins. SMS-E reduced renal inflammation and IL-1β levels in both the serum and kidneys. SMS-E inhibited both in vitro XO activity and urate uptake in URAT1-expressing oocytes. Using UPLC, 25 ginsenosides were identified, all of which were present in higher levels in SMS-E than in SMS-W.

Conclusion

SMS-E exhibited antihyperuricemic effects by regulating XO activity and renal urate transporters, providing the first evidence of its applicability in the treatment of hyperuricemia and gout.

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.

A Head-To-Head Comparison of Benzbromarone and Allopurinol on the Risk of Type 2 Diabetes Mellitus in People With Asymptomatic Hyperuricemia

Objective: The study aimed to thoroughly address the influence of benzbromarone and allopurinol on the risk of the development of type 2 diabetes mellitus (T2DM) in people with asymptomatic hyperuricemia. Methods: We conducted a retrospective cohort study to examine the 2000-2015 national dataset containing all claims data of 23 million beneficiaries in Taiwan. Subjects who already had diabetes mellitus, gout-related diseases, and any cancer prior to the index date were excluded. Asymptomatic hyperuricemia was defined as subjects taking urate-lowering drugs who never had a gout flare. Subjects aged 20-84 with asymptomatic hyperuricemia who had benzbromarone prescriptions were selected as the benzbromarone group. Sex-matched and age-matched subjects with asymptomatic hyperuricemia who had allopurinol prescriptions were identified as the allopurinol group. The maximum follow-up duration was set as 5 years in our study. The outcome was set as subjects who had a new diagnosis of T2DM. The incidence density of T2DM was calculated in the benzbromarone and allopurinol groups. The hazard ratio (HR) and 95% confidence interval (CI) for T2DM was utilized to estimate the association between medications and the risk of T2DM. Results: The incidence of T2DM among benzbromarone users was significantly lower than that of allopurinol users (7.91 versus 8.48 per 100 person-years, incidence rate ratio = 0.93, and 95% CI = 0.87-0.99). After adjustment for co-variables, the adjusted HR of T2DM would be 0.91 (95% CI = 0.85-0.98 and p = 0.008) in benzbromarone users as compared to allopurinol users. Conclusion: There is a small but statistically significant risk reduction of developing T2DM in people with asymptomatic hyperuricemia taking benzbromarone as compared to those taking allopurinol during 5 years of follow-up. It indicates a future research direction for the use of individual urate-lowering drugs on the prevention of T2DM in the general population.

Bis-thiobarbiturates as Promising Xanthine Oxidase Inhibitors: Synthesis and Biological Evaluation

Xanthine oxidase (XO) is the enzyme responsible for the conversion of endogenous purines into uric acid. Therefore, this enzyme has been associated with pathological conditions caused by hyperuricemia, such as the disease commonly known as gout. Barbiturates and their congeners thiobarbiturates represent a class of heterocyclic drugs capable of influencing neurotransmission. However, in recent years a very large group of potential pharmaceutical and medicinal applications have been related to their structure. This great diversity of biological activities is directly linked to the enormous opportunities found for chemical change off the back of these findings. With this in mind, sixteen bis-thiobarbiturates were synthesized in moderate to excellent reactional yields, and their antioxidant, anti-proliferative, and XO inhibitory activity were evaluated. In general, all bis-thiobarbiturates present a good antioxidant performance and an excellent ability to inhibit XO at a concentration of 30 µM, eight of them are superior to those observed with the reference drug allopurinol (Allo), nevertheless they were not as effective as febuxostat. The most powerful bis-thiobarbiturate within this set showed in vitro IC₅₀ of 1.79 μM, which was about ten-fold better than Allo inhibition, together with suitable low cytotoxicity. In silico molecular properties such as drug-likeness, pharmacokinetics, and toxicity of this promising barbiturate were also analyzed and herein discussed.

Where Epigenetics Meets Food Intake: Their Interaction in the Development/Severity of Gout and Therapeutic Perspectives

Gout is the most frequent form of inflammatory arthritis in the world. Its prevalence is particularly elevated in specific geographical areas such as in the Oceania/Pacific region and is rising in the US, Europe, and Asia. Gout is a severe and painful disease, in which co-morbidities are responsible for a significant reduction in life expectancy. However, gout patients remain ostracized because the disease is still considered "self-inflicted", as a result of unhealthy lifestyle and excessive food and alcohol intake. While the etiology of gout flares is clearly associated with the presence of monosodium urate (MSU) crystal deposits, several major questions remain unanswered, such as the relationships between diet, hyperuricemia and gout flares or the mechanisms by which urate induces inflammation. Recent advances have identified gene variants associated with gout incidence. Nevertheless, genetic origins of gout combined to diet-related possible uric acid overproduction account for the symptoms in only a minor portion of patients. Hence, additional factors must be at play. Here, we review the impact of epigenetic mechanisms in which nutrients (such as ω-3 polyunsaturated fatty acids) and/or dietary-derived metabolites (like urate) trigger anti/pro-inflammatory responses that may participate in gout pathogenesis and severity. We propose that simple dietary regimens may be beneficial to complement therapeutic management or contribute to the prevention of flares in gout patients.

Optimal uric acid levels by febuxostat treatment and cerebral, cardiorenovascular risks: post hoc analysis of a randomised controlled trial

OBJECTIVES

Hyperuricaemia is recognised as an independent risk marker for cardiovascular and renal diseases. However, uric acid is a powerful free-radical scavenger, and the optimal level of serum uric acid (SUA) determining outcomes are unknown. This study explored whether interventional treatments for excessive SUA reduction were harmful and what constituted the optimal lowering of SUA levels for the prevention of events in patients with asymptomatic hyperuricaemia.

METHODS

This was a post hoc analysis of a randomised trial (Febuxostat for Cerebral and CaRdiorenovascular Events PrEvEntion StuDy [FREED]) in which 1070 older patients with asymptomatic hyperuricaemia were enrolled and allocated to febuxostat (n = 537) or non-febuxostat treatment group (n = 533). We assessed the relationship between the end point (withdrawal or study completion) SUA levels and clinical outcomes. Primary end point was defined as a composite of all-cause mortality, cerebral and cardiorenovascular events.

RESULTS

In the febuxostat group, patients achieving SUA levels ≤4 mg/dl (hazard ratio: 2.01 [95% confidence interval: 1.05-3.87]), >4 to ≤ 5 mg/dl (2.12 [1.07-4.20], >6 to ≤ 7 mg/dl (2.42 [1.05-5.60]), and >7 mg/dl (4.73 [2.13-10.5]) had significantly higher risks for a primary composite event than those achieving SUA levels >5 to ≤ 6 mg/dl (p= 0.003 [log-rank test]). This J-shaped relationship applied to patients with renal impairment (p= 0.007 [Gray's test]) and was not significant in the non-febuxostat treatment group (p= 0.212 [log-rank test]).

CONCLUSION

Optimal SUA levels by febuxostat treatment is 5-6 mg/dl for reducing all-cause mortality, cerebral, cardiovascular, and renal events. Excessive SUA reduction may be harmful in older hyperuricaemic populations.

TRIAL REGISTRATION

ClinicalTrial.gov, https://clinicaltrials.gov, NCT01984749.

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

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

Acute Tumor Lysis Syndrome: A Metabolic Emergency in Cancer Patients

Tumor lysis syndrome (TLS) can be a life-threatening complication that occurs following the onset of chemotherapy treatment, most commonly in association with high-grade lymphoproliferative pathologies such as acute lymphoblastic leukemia and Burkitt lymphoma. The massive cell lysis caused by cytotoxic therapy leads to the rapid release in the blood of intracelullary products and the onset of severe metabolic and electrolytic complications (hyperkalemia, hyperphosphatemia, hypocalcemia and hyperuricemia) upto the acute renal failure. This article describes the incidence and pathophysiological basis of TLS, focusing on the new therapeutic strategies implemented over the last few years, especially with regard to the treatment of hyperuricemia. In particular, it highlights the characteristics of a recent drug, Rasburicase, as a safe and effective alternative, compared to traditional allopurinol therapy, for prophylaxis and treatment of children with hyperuricemia induced by chemotherapy.

Serum Uric Acid Is a Weak Independent Predictor of Overall Survival in Older Adults

Hyperuricemia accompanies many pathologies that contribute to overall death rate. The population-based multifaceted study of older adults in Poland made it possible to assess the effect of serum uric acid (SUA) on overall mortality. The PolSenior study performed between 2007–2011 included 3926 participants aged 65 years or above (mean age 79 ± 9 years) not treated with xanthin oxidase inhibitors (XOI) who were stratified by sex and SUA concentration into six subgroups increasing by 1 mg/dL. In 2019, survival data were retrieved from the population register. The crude risk of death was significantly higher in men and women with SUA ≥ 7 mg/dL. After adjustment to statistically significant factors, SUA remained a risk factor of death in men with SUA ≥ 8 mg/dL only, potentially due to the limited number of women with high SUA levels. Furthermore, age, heart failure, diabetes, and activities of daily living ≤ 4 pts were identified as factors increasing mortality risk regardless of sex. The risk of death increased also with smoking, past stroke, COPD/asthma, and hs-CRP > 3 mg/dL for men; and eGFR < 45 mL/min/1.73 m², mini nutritional assessment ≤ 7 pts, and loop diuretics use for women. Mild hyperuricemia is a significant health status marker and an independent risk factor for overall mortality in older Caucasians not receiving XOI. Increased mortality is mostly limited to subjects with SUA levels ≥ 8 mg/dL.

Uric acid extrarenal excretion: the gut microbiome as an evident yet understated factor in gout development

Humans do not produce uricase, an enzyme responsible for degrading uric acid. However, some bacteria residing in the gut can degrade one-third of the dietary and endogenous uric acid generated daily. New insights based on metagenomic and metabolomic approaches provide a new interest in exploring the involvement of gut microbiota in gout. Nevertheless, the exact mechanisms underlying this association are complex and have not been widely discussed. In this study, we aimed to review the evidence that suggests uric acid extrarenal excretion and gut microbiome are potential risk factors for developing gout. A literature search was performed in PubMed, Web of Science, and Google Scholar using several keywords, including "gut microbiome AND gout". A remarkable intestinal dysbiosis and shifts in abundance of certain bacterial taxa in gout patients have been consistently reported among different studies. Under this condition, bacteria might have developed adaptive mechanisms for de novo biosynthesis and salvage of purines, and thus, a concomitant alteration in uric acid metabolism. Moreover, gut microbiota can produce substrates that might cross the portal vein so the liver can generate de novo purinogenic amino acids, as well as uric acid. Therefore, the extrarenal excretion of uric acid needs to be considered as a factor in gout development. Nevertheless, further studies are needed to fully understand the role of gut microbiome in uric acid production and its extrarenal excretion, and to point out possible bacteria or bacterial enzymes that could be used as probiotic coadjutant treatment in gout patients.

Eggshell Membrane Ameliorates Hyperuricemia by Increasing Urate Excretion in Potassium Oxonate-Injected Rats

Hyperuricemia is the primary cause of gouty arthritis and other metabolic disorders. Eggshell membrane (EM) is an effective and safe supplement for curing pain and stiffness connected with osteoarthritis. However, the effect of EM on hyperuricemia is unclear. This study determines the effects of EM on potassium oxonate-injected hyperuricemia. Uric acid, creatinine, blood urea nitrogen concentrations in the serum, and xanthine oxidase activity in the liver are measured. Protein levels of renal urate transporter 1 (URAT1), organic anion transporters 1 (OAT1), glucose transporter 9 (GLUT9), and ATP-binding cassette transporter G2 (ABCG2) in the kidney are determined with renal histopathology. The results demonstrate that EM reduces serum uric acid levels and increases urine uric acid levels in hyperuricemic rats. Moreover, EM downregulates renal URAT1 protein expression, upregulates OAT1 and ABCG2, but does not change GLUT9 expression. Additionally, EM does not change xanthine oxidase activity in the liver or the serum. EM also decreases uric acid uptake into oocytes expressing hURAT1. Finally, EM markedly reduces renal inflammation and serum interleukin-1β levels. These findings suggest that EM exhibits antihyperuricemic effects by promoting renal urate excretion and regulating renal urate transporters. Therefore, EM may be useful in the prevention and treatment of gout and hyperuricemia.

Dosage individualization proposed for anti-gout medications among the patients with gout

BACKGROUND

The conventional one-size-fits-all approach has been criticized for almost all drugs used especially for chronic diseases, including gout. The present study was aimed to explore the need of individualization and optimization of the dose of anti-gout medications among gout patients.

METHODS

Cross-sectional study was carried out among 384 randomly selected new gout patients visiting two gout treatment centers at Lalitpur Metropolitan City, Nepal and who were taking antigout medications. Patients not taking anti-gout medications and not showing willingness to participate were excluded. The eGFR was calculated with the CKD Epidemiology Collaboration (CKD-EPI) creatinine equation (2009). Doses to be individualized were decided based on the Renal Drug Handbook and verified with the BNF 80. Data were analyzed via R 4.0.3 by applying the multinomial logistic regression to analyze statistical significance of risk with various predictors, and considering a p-value <0.05 statistically significant. Comorbidities were coded as per the ICD-11 coding and medicines were coded according to the WHO Guidelines for ATC classification and DDD assignment 2020.

RESULTS

The high risk of progression to CKD increased in the age range 54-63 and ≥84 years by 17.77 and 43.02 times, respectively. Also, high risk increased by 29.83 and 20.2 times for the overweight and the obese respectively. Aceclofenac 100mg was prescribed for maximum patients (30.5%). Need of dose individualization was realized in 30 patients, with maximum (7) in case of etoricoxib 90mg. Various glucocorticoids were prescribed for 36.9% patients, out of whom 3.8%required dose individualization and 15.9% patients with xanthine oxidase inhibitors, out of whom 1.3% required dose individualization.

CONCLUSION

Thirty cases required dose individualization, which was although minimal but could have meaningful impact on the clinical success of the individual patient. Based on the recommendation on dose individualization, those patients could be optimized on their therapy on future follow ups.

A brief review of urate transporter 1 (URAT1) inhibitors for the treatment of hyperuricemia and gout: Current therapeutic options and potential applications

Hyperuricemia is a common metabolic condition, cause by increased levels of serum urate (SUA). Reduced excretion of uric acid is reported as the key factor of primary hyperuricemia, accounting for approximately 90% of the cases. Urate transporter 1 (URAT1) is a major protein involved in uric acid reabsorption (about 90%). Therefore, URAT1 inhibitors are considered to be a highly effective and promising class of uricosuric agents for treating hyperuricemia. This review summarizes the development of URAT1 inhibitors for the treatment of hyperuricemia, including approved URAT1 inhibitors, URAT1 inhibitors under development in clinical trials, substances with URAT1 inhibitory effects from derivatives and natural products, and conventional drugs with new uses. This review provides new ideas regarding research on URAT1 inhibitors by introducing the structure, properties, and side effects of chemical drugs, as well as the sources and categories of natural drugs. We also discuss new mechanisms of classic drugs, which may provide guidance to many practicing clinicians. The research and discovery of new inhibitors remain in full swing, and tremendous developments are expected in the field.

The impact of an URAT1 polymorphism on the losartan treatment of hypertension and hyperuricemia

BACKGROUND

This study was designed to evaluate the impact of polymorphisms in the urate transporter 1 (URAT1) gene on the uricosuric action of losartan therapy in hypertensive patients suffering from hyperuricemia.

METHODS

A MassARRAY approach was used to detect single nucleotide polymorphism (SNP) loci in the URAT1 and CYP2C9 genes (16 and 2 loci, respectively) in 111 patients with hypertension and hyperuricemia taking losartan and in 121 healthy controls. In addition, we compared serum urate (SUA) levels and other key clinical biochemistry indices between these two patient groups.

RESULTS

We detected significant differences between the two patient groups with respect to age, SUA, urea, creatine, triglycerides, high-density lipoprotein, low-density lipoprotein, and fasting plasma glucose (all p < 0.05). In addition, we found that hypertensive patients with hyperuricemia were more likely to exhibit the rs3825016(C/T) (36.9% vs 21.5%, p = 0.03), and we determined that a 2-week treatment course with losartan was associated with significant decreases in SUA values (p < 0.001).

CONCLUSION

Our findings indicate that the URAT1 rs3825016 polymorphism may influence the uricosuric action of losartan.

Biomarkers of iron status in allopurinol-treated renal stone patients

Limited evidence exists on the effect of xanthine oxidase inhibitors in nephrolithiasis patients on iron status markers, beyond their effects on urate. The aim of this study was to investigate whether allopurinol therapy was associated with a significant impact on parameters related to iron status, in patients with renal stones. Allopurinol treatment was associated with a nonsignificant decline in serum uric acid. There were no significant differences in serum levels of transferrin and ferritin after treatment with allopurinol compared to pre-treatment levels. A non-significant fall in serum levels of haptoglobin was registered. The drug was associated with a significant rise in serum iron levels. Serum uric acid and iron did not show a significant correlation with any parameter in the study. Allopurinol exerted an overall non-significant effect on iron metabolism in nephrolithiasis patients, save for serum iron, this entails lack of untoward effects in populations with-iron related conditions.

Urate oxidase loaded in PCN-222(Fe) with peroxidase-like activity for colorimetric detection of uric acid

In the past two decades, the number of reports on the construction of uric acid (UA) sensors has increased dramatically, as it is a vital factor in the diagnosis of physiological functions and diseases. Among these sensors, cascade colorimetric detection based on peroxidase mimics has received great attention owing to the advantages of easier operation and more intuitive results. Herein, we report a simple UA detection method via the integration of urate oxidase (UOx) and PCN-222(Fe) with peroxidase-like activity, in which UOx is immobilized in PCN-222(Fe) by physical adsorption. UOx could catalyze the UA oxidation to produce H₂O₂, and then PCN-222(Fe) catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H₂O₂ to generate a blue product with a maximum absorbance at 652 nm. Under optimal conditions, the increasing absorbance at 652 nm was proportional to the UA concentration. The linear range for UA detection was 10-800 μM with a limit of detection of 3.5 μM, and the cascade system has been successfully utilised for the detection of UA in human serum samples to demonstrate the accuracy of the proposed method. In conclusion, the cascade catalytic system based on the immobilization of UOx in PCN-222(Fe) has the potential to be used as a rapid and sensitive sensor for UA detection.

Increased Systolic Blood Pressure Mediates the Relationship Between Urate and Gout Risk in Indonesia: A Novel Application of a Partial Least Squares-Structural Equation Model

BACKGROUND

Most Indonesians with hyperuricemia are less than 40 years old, which suggests an increasing gout risk in the country. Meanwhile, untreated hyperuricemia was also suggested to lead to hypertension. Yet, it is unclear whether blood pressure (BP) plays a mediating role between urate and gout.

OBJECTIVE

We investigated the mediating effect of BP between urate and gout risk in Indonesians using a partial least squares-structural equation model.

METHOD

A community-based retrospective case-control study was conducted between July 1 and August 31, 2019 in Indonesia. We randomly recruited 397 participants, including 86 patients with gout and 311 healthy controls from seven community health service centers. Multivariate logistic regression was employed to analyze the adjusted odds ratios of the association between risk factors, such as urate level and BP, and gout risk after controlling for other covariates. A path analysis was utilized to analyze the mediating effect of systolic BP between urate and gout. The STROBE reporting guideline for the observational study is adopted in our reporting.

RESULT

We found that a 1 mg/dL increase of urate level significantly increased gout risk with an OR of 4.97 (95% CI: 3.48-7.09) and an AOR of 4.44 (95% CI: 3.07-6.42) after adjusting for covariates. The association between urate and gout was also significantly mediated by systolic BP (β = 0.05; 95% CI Bias Corrected [0.02-0.08], p < 0.001).

CONCLUSION

Urate was significantly associated with gout risk and was possibly mediated by increased systolic BP in Indonesians. Controlling systolic BP could be one of the strategies to decrease the risk of gout for individuals with hyperuricemia. Health education can be carried out by community health nurses to individuals on controlling their urate level and systolic BP to decrease the gout risk among Indonesian.

Hyperuricemia-induced endothelial insulin resistance: the nitric oxide connection

Hyperuricemia, defined as elevated serum concentrations of uric acid (UA) above 416 µmol L^-1, is related to the development of cardiometabolic disorders, probably via induction of endothelial dysfunction. Hyperuricemia causes endothelial dysfunction via induction of cell apoptosis, oxidative stress, and inflammation; however, it's interfering with insulin signaling and decreased endothelial nitric oxide (NO) availability, resulting in the development of endothelial insulin resistance, which seems to be a major underlying mechanism for hyperuricemia-induced endothelial dysfunction. Here, we elaborate on how hyperuricemia induces endothelial insulin resistance through the disruption of insulin-stimulated endothelial NO synthesis. High UA concentrations decrease insulin-induced NO synthesis within the endothelial cells by interfering with insulin signaling at either the receptor or post-receptor levels (i.e., proximal and distal steps). At the proximal post-receptor level, UA impairs the function of the insulin receptor substrate (IRS) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) in the insulin signaling pathway. At the distal level, high UA concentrations impair endothelial NO synthase (eNOS)-NO system by decreasing eNOS expression and activity as well as by direct inactivation of NO. Clinically, UA-induced endothelial insulin resistance is translated into impaired endothelial function, impaired NO-dependent vasodilation, and the development of systemic insulin resistance. UA-lowering drugs may improve endothelial function in subjects with hyperuricemia.

Urate Transporters in the Kidney: What Clinicians Need to Know

Urate is produced in the liver by the degradation of purines from the diet and nucleotide turnover and excreted by the kidney and gut. The kidney is the major route of urate removal and has a pivotal role in the regulation of urate homeostasis. Approximately 10% of the glomerular filtered urate is excreted in the urine, and the remainder is reabsorbed by the proximal tubule. However, the transport of urate in the proximal tubule is bidirectional: reabsorption and secretion. Thus, an increase in reabsorption or a decrease in secretion may induce hyperuricemia. In contrast, a decrease in reabsorption or an increase in secretion may result in hyperuricosuria. In the proximal tubule, urate reabsorption is mainly mediated by apical URAT1 (SLC22A12) and basolateral GLUT9 (SLC2A9) transporter. OAT4 (SLC22A11) also acts in urate reabsorption in the apical membrane, and its polymorphism is associated with the risk of hyperuricemia. Renal hypouricemia is caused by SLC22A12 or SLC2A9 loss-of-function mutations, and it may be complicated by exercise-induced acute kidney injury. URAT1 and GLUT9 are also drug targets for uricosuric agents. Sodium-glucose cotransporter inhibitors may induce hyperuricosuria by inhibiting GLUT9b located in the apical plasma membrane. Urate secretion is mediated by basolateral OAT1 (SLC22A6) and OAT3 (SLC22A8) and apical ATP-binding cassette super-family G member 2 (ABCG2), NPT1 (SLC17A1), and NPT4 (SLC17A3) transporter in the proximal tubule. NPT1 and NPT4 may be key players in renal urate secretion in humans, and deletion of SLC22A6 and SLC22A8 in mice leads to decreased urate excretion. Dysfunctional variants of ABCG2 inhibit urate secretion from the gut and kidney and may cause gout. In summary, the net result of urate transport in the proximal tubule is determined by the dominance of transporters between reabsorption (URAT1, OAT4, and GLUT9) and secretion (ABCG2, NPT1, NPT4, OAT1, and OAT3).

Influence of SGLT2 Inhibitor Treatment on Urine Antioxidant Status in Type 2 Diabetic Patients: A Pilot Study

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have been recognized as potent antioxidant agents. Since SGLT2i are nephroprotective drugs, we aimed to examine the urine antioxidant status in patients with type 2 diabetes mellitus (T2DM). One hundred and one subjects participated in this study, including 37 T2DM patients treated with SGLT2i, 31 T2DM patients not using SGLT2i, and 33 healthy individuals serving as a control group. Total antioxidant capacity (TAC), superoxide dismutase (SOD), manganese superoxide dismutase (MnSOD), free thiol groups (R-SH, sulfhydryl groups), and catalase (CAT) activity, as well as glucose concentration, were assessed in the urine of all participants. Urine SOD and MnSOD activity were significantly higher among T2DM patients treated with SGLT2i than T2DM patients without SGLT2i treatment (p = 0.009 and p = 0.003, respectively) and to the healthy controls (p = 0.002 and p = 0.001, respectively). TAC was significantly lower in patients with T2DM treated with SGLT2i when compared to those not treated and healthy subjects (p = 0.036 and p = 0.019, respectively). It could be hypothesized that the mechanism by which SGLT2i provides nephroprotective effects involves improvement of the SOD antioxidant activity. However, lower TAC might impose higher OS (oxidative stress), and elevation of SOD activity might be a compensatory mechanism.

An update of genetics, co-morbidities and management of hyperuricaemia

Hyperuricaemia (HU) caused by disorders of purine metabolism is a metabolic disease. A number of epidemiological reports have confirmed that HU is correlated with multiple disorders, such as chronic kidney diseases, cardiovascular disease and gout. Recent studies showed that the expression and functional changes of uric acid transporters, including URAT1, GLUT9 and ABCG2, were associated with HU. Moreover, a large number of genome-wide association studies have shown that these transporters' dysfunction leads to HU. In this review, we describe the recent progress of aetiology and related transporters of HU, and we also summarise the common co-morbidities possible mechanisms, as well as the potential pharmacological and non-pharmacological treatment methods for HU, aiming to provide new ideas for the treatment of HU.

Interrogation of the perturbed gut microbiota in gouty arthritis patients through in silico metabolic modeling

Recent studies have shown perturbed gut microbiota associated with gouty arthritis, a metabolic disease characterized by an imbalance between uric acid production and excretion. To mechanistically investigate altered microbiota metabolism associated with gout disease, 16S rRNA gene amplicon sequence data from stool samples of gout patients and healthy controls were computationally analyzed through bacterial community metabolic models. Patient-specific community models constructed with the metagenomics modeling pipeline, mgPipe, were used to perform k-means clustering of samples according to their metabolic capabilities. The clustering analysis generated statistically significant partitioning of samples into a Bacteroides-dominated, high gout cluster and a Faecalibacterium-elevated, low gout cluster. The high gout cluster was predicted to allow elevated synthesis of the amino acids D-alanine and L-alanine and byproducts of branched-chain amino acid catabolism, while the low gout cluster allowed higher production of butyrate, the sulfur-containing amino acids L-cysteine and L-methionine, and the L-cysteine catabolic product H2S. By expanding the capabilities of mgPipe to provide taxa-level resolution of metabolite exchange rates, acetate, D-lactate and succinate exchanged from Bacteroides to Faecalibacterium were predicted to enhance butyrate production in the low gout cluster. Model predictions suggested that sulfur-containing amino acid metabolism generally and H2S more specifically could be novel gout disease markers.

The biology of urate

Urate is the end-product of the purine metabolism in humans. The dominant source of urate is endogenous purines and the remainder comes through diet. Approximately two thirds of urate is eliminated via the kidney with the rest excreted in the feces. While the transporter BCRP, encoded by ABCG2, has been found to play a role in both the gut and kidney, SLC22A12 and SLC2A9 encoding URAT1 and GLUT9, respectively, are the two transporters best characterized. Only 8-12% of the filtered urate is excreted by the kidney. Renal elimination of urate depends substantially on specific transporters, including URAT1, GLUT9 and BCRP. Studies that have assessed the biologic effects of urate have produced highly variable results. Although there is a suggestion that urate may have anti-oxidant properties in some circumstances, the majority of evidence indicates that urate is pro-inflammatory. Hyperuricemia can result in the formation of monosodium urate (MSU) crystals that may be recognized as danger signals by the immune system. This immune response results in the activation of the NLRP3 inflammasome and ultimately in the production and release of interleukin-1β, and IL-18, that mediate both inflammation, pyroptotic cell death, and necroinflammation. It has also been demonstrated that soluble urate mediates effects on the kidney to induce hypertension and can induce long term epigenetic reprogramming in myeloid cells to induce "trained immunity." Together, these sequelae of urate are thought to mediate most of the physiological effects of hyperuricemia and gout, illustrating this biologically active molecule is more than just an "end-product" of purine metabolism.

Modulation of Urate Transport by Drugs

BACKGROUND

Serum urate (SU) levels in primates are extraordinarily high among mammals. Urate is a Janus-faced molecule that acts physiologically as a protective antioxidant but provokes inflammation and gout when it precipitates at high concentrations. Transporters play crucial roles in urate disposition, and drugs that interact with urate transporters either by intention or by accident may modulate SU levels. We examined whether in vitro transporter interaction studies may clarify and predict such effects.

METHODS

Transporter interaction profiles of clinically proven urate-lowering (uricosuric) and hyperuricemic drugs were compiled from the literature, and the predictive value of in vitro-derived cut-offs like C_max/IC₅₀ on the in vivo outcome (clinically relevant decrease or increase of SU) was assessed.

RESULTS

Interaction with the major reabsorptive urate transporter URAT1 appears to be dominant over interactions with secretory transporters in determining the net effect of a drug on SU levels. In vitro inhibition interpreted using the recommended cut-offs is useful at predicting the clinical outcome.

CONCLUSIONS

In vitro safety assessments regarding urate transport should be done early in drug development to identify candidates at risk of causing major imbalances. Attention should be paid both to the inhibition of secretory transporters and inhibition or trans-stimulation of reabsorptive transporters, especially URAT1.

Identification of Abnormal Proteins in Plasma from Gout Patients by LC-MS/MS

A high level of uric acid may cause hyperuricemia, which further develops into gout, eventually leading to chronic kidney disease. However, the pathogenic mechanism remains largely unknown. To investigate the cause and block the transformation of hyperuricemia to related diseases, it is important to discover the alterations in protein levels between gout patients and non-gout individuals. To date, human blood plasma is still the predominant matrices for clinical analysis. Due to the high abundance, the proteins of plasma samples have strong shielding effects on low abundance proteins, thus, the information on low abundance protein expression is always masked, while the low abundance proteins of human plasma are often of great significance for the diagnosis and treatment of diseases. Therefore, it is very important to separate and analyze the plasma proteins. High-performance liquid chromatography (LC) tandem mass spectrometry (MS)-based proteomics has been developed as a powerful tool to investigate changes in the human plasma proteome. Here, we used LC-MS/MS to detect the differential proteins in the plasmas from simple gout patients, gout with kidney damage patients, and non-gout individuals. We identified 32 obviously differential proteins between non-gout and gout subjects and 10 differential proteins between simple gout and gout with kidney damage patients. These differential proteins were further analyzed to characterize their localization and functions. Additionally, the correlation analysis showed multiple relationships between the abnormal plasma proteins and clinical biochemical indexes, particularly for the immune-inflammatory response proteins. Furthermore, inflammation factors gelsolin (GSN) were confirmed. Our results offer a view of plasma proteins for studying biomarkers of gout patients.

Solid state characterization, solubility, intrinsic dissolution and stability behavior of allopurinol hydrochloride salt

Since each solid form of an active pharmaceutical ingredient (API) can exhibit particular physicochemical properties, the objectives of this work were to characterize and study the solubility/stability properties of allopurinol hydrochloride salt (ALO-HCl) for the first time. ALO-HCl was obtained through an unreported recrystallization process and studied by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). All characterization techniques were effective for the differentiation of ALO-HCl from the preferred pharmaceutical form (ALO). DSC and TGA studies showed a solid-state conversion from ALO-HCl to ALO upon HCl loss. Solubility and dissolution tests showed that ALO-HCl converts to ALO in aqueous media. Moreover, the effect of the common ion decreased the amount of drug released from ALO-HCl during the intrinsic dissolution assay in HCl medium. The stability studies showed a partial conversion from ALO-HCl to ALO after 6 months of storage. The results indicate that comparative studies between crystalline forms of APIs are of great importance, as they contribute to the understanding of aspects related to the quality of medicines.

A Brief Review of Analytical Methods for the Estimation of Allopurinol in Pharmaceutical Formulation and Biological Matrices

This review article represents the collection and discussion of various analytical methods available in the literature for the determination of allopurinol (ALLP) in pharmaceutical and biological samples consisting of HPLC, UV-visible method, near-IR spectroscopy, spectrofluorometry, capillary electrophoresis, polarography, voltammetry, and hyphenated techniques such as LC-MS, LC-MS/MS, UPLC-MS/MS, and GC-MS. The anticipated review provides details about the comparative utilization of various analytical techniques for the determination of ALLP. The present review article can be effectively explored to conduct future analytical investigation for the estimation of ALLP.

Molecular Imprinting Technology for Determination of Uric Acid

The review focuses on the overview of electrochemical sensors based on molecularly imprinted polymers (MIPs) for the determination of uric acid. The importance of robust and precise determination of uric acid is highlighted, a short description of the principles of molecular imprinting technology is presented, and advantages over the others affinity-based analytical methods are discussed. The review is mainly concerned with the electro-analytical methods like cyclic voltammetry, electrochemical impedance spectroscopy, amperometry, etc. Moreover, there are some scattered notes to the other electrochemistry-related analytical methods, which are capable of providing additional information and to solve some challenges that are not achievable using standard electrochemical methods. The significance of these overviewed methods is highlighted. The overview of the research that is employing MIPs imprinted with uric acid is mainly targeted to address these topics: (i) type of polymers, which are used to design uric acid imprint structures; (ii) types of working electrodes and/or other parts of signal transducing systems applied for the registration of analytical signal; (iii) the description of the uric acid extraction procedures applied for the design of final MIP-structure; (iv) advantages and disadvantages of electrochemical methods and other signal transducing methods used for the registration of the analytical signal; (vi) overview of types of interfering molecules, which were analyzed to evaluate the selectivity; (vi) comparison of analytical characteristics such as linear range, limits of detection and quantification, reusability, reproducibility, repeatability, and stability. Some insights in future development of uric acid sensors are discussed in this review.

Xanthine oxidase inhibitory activity and antihyperuricemic effect of Moringa oleifera Lam. leaf hydrolysate rich in phenolics and peptides

ETHNOPHARMACOLOGICAL RELEVANCE

Moringa oleifera Lam. leaf (MOL), a rich source of protein and phenolics, was traditionally used to treat various diseases including headaches, fevers, sore throat and dyslipidemia. Recently, MOL was reported to possess antioxidant, anti-dyslipidemia and hepato-renal protective activities, indicating that MOL could become a potential agent to improve metabolic disorders associated with hyperuricemia. The antihyperuricemic effect of MOL hydrolysate (MOLH) with high contents of phenolics and peptides remains unknown.

AIM OF THE STUDY

The aim of this study is to investigate xanthine oxidase (XO) inhibitory activity of MOLH, to clarify phenolic and peptide profiles of MOLH, and to evaluate possible mechanism underlying the antihyperuricemic effect of MOLH.

MATERIALS AND METHODS

MOLH was prepared by enzymatic hydrolysis using commercial trypsin. XO inhibitory activity was determined by XO reaction-UPLC-MS coupling method. The chemical profiles of the phenolic and peptide fractions of MOLH were determined by UPLC-QTOF-MS/MS. The antihyperuricemic effect of MOLH was evaluated in a potassium oxonate-induced hyperuricemic rat model at doses of 200 and 500 mg/kg. Serum uric acid (UA), urea nitrogen, creatinine (CRE), triglyceride (TG), total cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol levels, serum XO activity, liver malondialdehyde (MDA) equivalent level, renal tumor necrosis factor-α and interleukin-1β levels, and protein expression of renal urate-anion transporter 1, glucose transporter 9 and ATP-binding cassette transporter G2 were determined.

RESULTS

The phenolic and peptide fractions played key roles in inhibiting XO activity and blocking uric acid production. Five flavonoids and sixteen polypeptides were identified in the phenolic and peptide fractions of MOLH, respectively. MOLH (200 and 500 mg/kg) could effectively reduce the serum UA level of hyperuricemic rats (p < 0.001) by regulation of serum XO activity (p < 0.05 at 200 mg/kg, p < 0.01 at 500 mg/kg) and renal urate transporters. Besides, MOLH could improve metabolic disorders associated with hyperuricemia by its multiple actions on liver MDA (p < 0.001), serum CRE (p < 0.05 at 500 mg/kg) and serum TG (p < 0.001).

CONCLUSION

The results provided scientific evidence that MOLH rich in phenolics and peptides ameliorated hyperuricemia and metabolic disorders. This study validated the potential use of MOLH for regulation of hyperuricemia.

Renal Diseases Associated with Hematologic Malignancies and Thymoma in the Absence of Renal Monoclonal Immunoglobulin Deposits

In addition to kidney diseases characterized by the precipitation and deposition of overproduced monoclonal immunoglobulin and kidney damage due to chemotherapy agents, a broad spectrum of renal lesions may be found in patients with hematologic malignancies. Glomerular diseases, in the form of paraneoplastic glomerulopathies and acute kidney injury with various degrees of proteinuria due to specific lymphomatous interstitial and/or glomerular infiltration, are two major renal complications observed in the lymphoid disorder setting. However, other hematologic neoplasms, including chronic lymphocytic leukemia, thymoma, myeloproliferative disorders, Castleman disease and hemophagocytic syndrome, have also been associated with the development of kidney lesions. These renal disorders require prompt recognition by the clinician, due to the need to implement specific treatment, depending on the chemotherapy regimen, to decrease the risk of subsequent chronic kidney disease. In the context of renal disease related to hematologic malignancies, renal biopsy remains crucial for accurate pathological diagnosis, with the aim of optimizing medical care for these patients. In this review, we provide an update on the epidemiology, clinical presentation, pathophysiological processes and diagnostic strategy for kidney diseases associated with hematologic malignancies outside the spectrum of monoclonal gammopathy of renal significance.

Anti-Inflammatory and Anti-Hyperuricemic Effects of Chrysin on a High Fructose Corn Syrup-Induced Hyperuricemia Rat Model via the Amelioration of Urate Transporters and Inhibition of NLRP3 Inflammasome Signaling Pathway

Hyperuricemia is the main cause of gout and involved in the occurrence of many other diseases such as hyperlipidemia and hypertension correlated with metabolic disorders. Chrysin is a flavonoid compound found naturally in honey, propolis, and mushrooms and has anti-inflammatory and antioxidant effects. However, its mechanism of action is not clear yet. This study investigated the mechanism of chrysin’s anti-hyperuricemic effect in hyperuricemia-induced rats fed with high-fructose corn syrup. Orally administrated chrysin for 28 consecutive days effectively decreased uric acid by inhibiting the activity of xanthine oxidase (XO) in the liver. Moreover, chrysin markedly downregulated the protein expression of uric acid transporter 1 (URAT1) and glucose transporter type 9 (GLUT9) and upregulated the protein expression of organic anion transporter 1 (OAT1) and human ATP-binding cassette subfamily G-2 (ABCG2). In addition, chrysin showed prominent anti-oxidative and inflammatory effects as the malondialdehyde (MDA) and interleukin 1 beta (IL-1β) concentration was reduced in both rat kidney and serum, which aligned with the inhibition of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome signaling pathway activation. Collectively, our results strongly suggest that chrysin exhibits potent anti-hyperuricemic and anti-inflammatory effects that may yield new adjuvant treatments for gout.

Serum Uric Acid Levels and Risk of Eight Site-Specific Cancers: A Mendelian Randomization Study

The relationship between serum uric acid (UA) levels and cancer risk remains controversial. Here, a two-sample Mendelian randomization analysis was performed to identify a causal effect of serum UA levels on cancer risk. Twenty-six single nucleotide polymorphisms strongly associated with serum UA levels were screened as genetic variants from large-scale meta-analysis data of a genome-wide association study of 110,347 European individuals. Genetic associations with eight common site-specific cancers were subsequently explored. A total of six Mendelian randomization methods were used to estimate the potential effect of serum UA levels on cancer risk, including random effects inverse variance weighting, fix effects inverse variance weighting, MR-Egger, median weighting, mode weighting, and simple mode analysis. Our primary random effects inverse variance weighted analysis revealed that no significant associations with cancers was found (all p > 0.05). Sensitivity analyses and additional analyses also showed similar pooled results. In conclusion, no significant causality between serum UA levels and cancer risk was evidenced.

Efficacy and safety of a selective URAT1 inhibitor SHR4640 in Chinese subjects with hyperuricemia: a randomized controlled phase II study

OBJECTIVES

To evaluate the efficacy and safety of SHR4640, a highly selective urate transporter 1 inhibitor in Chinese subjects with hyperuricemia.

METHODS

This was a randomized double-blind dose-ranging phase II study. Subjects whose serum uric acid levels ≥480 µmol/l with gout, or sUA levels ≥480 µmol/l without gout but with comorbidities, or sUA levels ≥540 µmol/l were enrolled. Subjects were randomly assigned (1:1:1:1:1) to receive once daily 2.5 mg/5 mg/10 mg of SHR4640, 50 mg of benzbromarone, and placebo, respectively. The primary end point was the proportion of subjects achieved target sUA level of ≤ 360 µmol/l at week 5.

RESULTS

About 99.5% of subjects (n = 197) were male and 95.9% of subjects had gout history. The proportions of subjects achieved target sUA at week 5 were 32.5%, 72.5% and 61.5% in 5 mg, 10 mg of SHR4640 and benzbromarone groups, respectively, significantly higher than placebo group (0%; p< 0.05 for 5 mg and 10 mg of SHR4640 group). The sUA was reduced by 32.7%, 46.8% and 41.8% at week 5 with 5 mg, 10 mg of SHR4640 and benzbromarone, respectively, vs placebo (5.9%; p< 0.001 for each comparison). The incidences of gout flares requiring intervention were similar among all groups. Occurrences of treatment-emergent adverse events (TEAEs) were comparable across all groups, and serious TEAEs were not reported.

CONCLUSIONS

The present study indicated a superior sUA-lowering effect, and well tolerated safety profile after 5-week treatment with once-daily 5 mg/10 mg of SHR4640 as comparing with placebo in Chinese subjects with hyperuricemia.

TRIAL REGISTRATION

ClinicalTrials.gov number, NCT03185793.

Sex differences in response to allopurinol and benzbromarone in gout: a retrospective cohort study

Objective

Owing to lower mean uric acid excretion in women compared with men, uricosuric agents might be preferred in women over xanthine oxidase (XO) inhibitors. We therefore investigated the differences in response to two urate-lowering therapies (ULTs) with different modes of action within and between sexes.

Methods

This retrospective cohort study included patients with a clinical diagnosis of gout who started allopurinol and/or benzbromarone. The successful response to ULT, defined as reaching a serum uric acid (sUA) target of <0.36 mmol/l within 6 months after commencing ULT, was compared between allopurinol and benzbromarone in women and men. Effect modification by sex on differences in response was evaluated.

Results

Allopurinol was started in 255 women and 1045 men, and benzbromarone in 60 women and 205 men. After 6 months, the proportions of women reaching the sUA target were 58.4% and 66.7% for allopurinol and benzbromarone, respectively (difference, −8%; 95% CI: −22%, 5%). The respective proportions in men were 61.0% and 75.6%, respectively (difference, −15%; 95% CI: −21%, −8%). Corrected for confounding, the odds ratio (OR) of reaching the target on benzbromarone vs allopurinol within women was 0.91 (95% CI: 0.47, 1.75), and within men 1.55 (95% CI: 1.04, 2.32). Corrected for confounding, sex was not an effect modifier of the difference in allopurinol and benzbromarone response (OR, 0.59; 95% CI: 0.28, 1.24).

Conclusion

This study did not demonstrate between-sex differences regarding the response to either a uricosuric agent or an XO inhibitor, negating different treatment choices by sex.

Uric acid-induced pancreatic β-cell dysfunction

Hyperuricemia is associated with insulin resistance, pancreatic β-cell dysfunction and consequently with development of type 2 diabetes. Although a direct relationship between high levels of uric acid (UA) and the development of diabetes is still a controversial issue, there is some evidence that strongly points to pancreatic β-cells damage as a result of high serum UA levels. Here, the mechanisms underlying UA-induced β-cell damage are discussed. Available literature indicates that UA can decrease glucose-stimulated insulin secretion and cause β-cell death. The mechanisms underlying these effects are UA-induced oxidative stress and inflammation within the β-cells. UA also stimulates inducible nitric oxide (NO) synthase (iNOS) gene expression leading to NO-induced β-cell dysfunction. Thus hyperuricemia may potentially cause β-cell dysfunction, leading to diabetes. It may be hypothesized that in hyperuricemic subjects, UA-lowering drugs may be beneficial in preventing diabetes.

Acupuncture to treat asymptomatic hyperuricemia: A protocol for systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Hyperuricemia (HUA) plays an important role in metabolic syndrome, cardiovascular disease, and kidney disease. HUA without resulting gout is referred to as asymptomatic HUA. The purpose of the present systematic review protocol is to provide methods to assess the effectiveness and safety of acupuncture-based treatment for asymptomatic HUA.

METHODS

To identify randomized controlled trials (RCTs) involving acupuncture-based treatment for asymptomatic HUA, a search will be carried out using the following eight electronic databases: MEDLINE, EMBASE, Cochrane Library, Korea Med, Oriental Medicine Advanced Searching Integrated System, Korean Studies Information Service System, China National Knowledge Infrastructure, and Japanese Institutional Repositories Online. Manual search and email contact with the author will also be conducted if necessary. Studies will be selected based on predefined criteria and summarized data regarding study participants, interventions, control groups, outcome measures, side effects, and risk of bias. No language restrictions will be imposed. Studies that evaluated any type of acupuncture will be eligible for inclusion, and the primary outcome will be the blood uric acid level. The methodological quality of the included RCTs will be assessed using the Cochrane risk of bias tool.

RESULTS

The present study will evaluate the efficacy and safety of acupuncture to treat HUA.

CONCLUSION

Our findings will establish the evidence for acupuncture-based treatment of HUA and will be informative for patients with HUA, clinicians, policy makers, and researchers.

REGISTRATION NUMBER

reviewregistry1054.

Prevalence of Hyperuricemia and the Use of Allopurinol in Older Poles-Results from a Population-Based PolSenior Study

BACKGROUND

Our study analyzes the frequency and risk factors of hyperuricemia and the use of allopurinol in a representative cohort of the older Polish adult population.

METHODS

The analysis was a part of a cross-sectional PolSenior study on aging in Poland. The complete medication data were available in 4873 out of 4979 community dwelling respondents aged 65 and over. Serum uric acid concentrations were evaluated in 4028 participants (80.9% of the cohort).

RESULTS

Hyperuricemia was observed in 28.2% of women and 24.7% of men. Ten risk factors of hyperuricemia were selected based on multivariable LASSO logistic regression analysis. Nine factors showed significant odds ratios: eGFR < 60 mL/min/1.73 m2 (OR = 4.10), hypertriglyceridemia (OR = 1.88), obesity (OR = 1.75), heart failure (1.70), CRP > 3.0 mg/dL (OR = 1.64), coronary artery disease (OR = 1.30), use of loop-diuretics (OR = 4.20), hydrochlorothiazide (OR = 2.96), and thiazide-like diuretics (OR = 2.81). Allopurinol was used by 2.8% of men and 1.8% of women. The therapy was considered effective in 46.7% of men and 53.3% of women.

CONCLUSIONS

Hyperuricemia was present in 23.1% (95% CI: 21.8-24.4) of the older Polish population. The frequency of hyperuricemia increases with age, reaching 30.5% in men and 33.7% in women aged 90 years or more. Chronic kidney disease, obesity, heart failure, hypertriglyceridemia, and the use of diuretics were the strongest risk factors for hyperuricemia in older adults. The treatment with allopurinol was ineffective in more than half of participants.

Therapeutic Targeting of SGLT2: A New Era in the Treatment of Diabetes and Diabetic Kidney Disease

As the prevalence of diabetic kidney disease (DKD) continues to rise, so does the need for a novel therapeutic modality that can control and slow its progression to end-stage renal disease. The advent of sodium-glucose cotransporter-2 (SGLT2) inhibitors has provided a major advancement for the treatment of DKD. However, there still remains insufficient understanding of the mechanism of action and effectiveness of this drug, and as a result, its use has been very limited. Burgeoning evidence suggests that the SGLT2 inhibitors possess renal protective activities that are able to lower glycemic levels, improve blood pressure/hemodynamics, cause bodyweight loss, mitigate oxidative stress, exert anti-inflammatory and anti-fibrotic effects, reduce urinary albumin excretion, lower uric acid levels, diminish the activity of intrarenal renin-angiotensin-aldosterone system, and reduce natriuretic peptide levels. SGLT2 inhibitors have been shown to be safe and beneficial for use in patients with a GFR ≥30mL/min/1.73m², associated with a constellation of signs of metabolic reprogramming, including enhanced ketogenesis, which may be responsible for the correction of metabolic reprogramming that underlies DKD. This article aims to provide a comprehensive overview and better understanding of the SGLT2 inhibitor and its benefits as it pertains to renal pathophysiology. It summarizes our recent understanding on the mechanisms of action of SGLT2 inhibitors, discusses the effects of SGLT2 inhibitors on diabetes and DKD, and presents future research directions and therapeutic potential.

A 12-Week, Multicenter, Randomized, Double-Blind, Placebo-Controlled Clinical Trial for Evaluation of the Efficacy and Safety of DKB114 on Reduction of Uric Acid in Serum

This study sought to investigate the antihyperuricemia efficacy and safety of DKB114 (a mixture of Chrysanthemum indicum Linn flower extract and Cinnamomum cassia extract) to evaluate its potential as a dietary supplement ingredient. This clinical trial was a randomized, 12-week, double-blind, placebo-controlled study. A total of 80 subjects (40 subjects with an intake of DKB114 and 40 subjects with that of placebo) who had asymptomatic hyperuricemia (7.0–9.0 mg/dL with serum uric acid) was randomly assigned. No significant difference between the DKB114 and placebo groups was observed in the amount of uric acid in serum after six weeks of intake. However, after 12 weeks of intake, the uric acid level in serum of subjects in the DKB114 group decreased by 0.58 ± 0.86 mg/dL and was 7.37 ± 0.92 mg/dL, whereas that in the placebo group decreased by 0.02 ± 0.93 mg/dL and was 7.67 ± 0.89 mg/dL, a significant difference (p = 0.0229). In the analysis of C-reactive protein (CRP) change, after 12 weeks of administration, the DKB114 group showed an increase of 0.05 ± 0.27 mg/dL (p = 0.3187), while the placebo group showed an increase of 0.10 ± 0.21 mg/dL (p = 0.0324), a statistically significant difference (p = 0.0443). In the analysis of amount of change in apoprotein B, after 12 weeks of administration, the DKB114 group decreased by 4.75 ± 16.69 mg/dL (p = 0.1175), and the placebo group increased by 3.13 ± 12.64 mg/dL (p = 0.2187), a statistically significant difference between the administration groups (p = 0.0189). In the clinical pathology test, vital signs and weight measurement, and electrocardiogram test conducted for safety evaluation, no clinically significant difference was found between the ingestion groups, confirming the safety of DKB114. Therefore, it may have potential as a treatment for hyperuricemia and gout. We suggest that DKB114 as a beneficial and safe food ingredient for individuals with high serum uric acid. Trial registration (CRIS.NIH. go. Kr): KCT0002840.

Nutritional benefits, phytochemical constituents, ethnomedicinal uses and biological properties of Miracle fruit plant (Synsepalum dulcificum Shumach. & Thonn. Daniell)

Miracle fruit plant or Miracle berry plant (Synsepalum dulcificum) is a peculiar medicinal plant because of the unique taste-modifying property of its fruit which is due to the presence of the glycoprotein, miraculin. This property has been known for centuries to the people of tropical Western and Central Africa who also employ different parts of the plant in the management of various ailments. Scientific investigations have unravelled several pharmacological properties of the plant which include antidiabetic, blood cholesterol-lowering, anti-hyperuricaemia, antioxidant, anticonvulsant and anticancer properties. Also, subacute administration of the plant extract up to 200 mg/kg was not found to be toxic in rats. Apart from miraculin, other pharmacologically active compounds have been identified in the plant including alkaloids (dihydro-feruloyl-5-methoxytyramine, N-cis-caffeoyltyramine, N-cis-feruloyl-tyramine), lignins (+-syringaresinol, +-epi-syringaresinol), phytosterols, triterpenoids, phenolic acids, flavonoids, and amino acids. The plant has also been credited with notable nutritional benefits. Proper documentation of available information on folkloric use, biological activity, constituent phytocompounds, and nutritional benefits of ethnobotanicals will go a long way in affording optimal benefits from their therapeutic potentials. This can also aid in the conservation of species at risk of extinction. This work presents an up-to-date review of the ethnobotany, phytochemistry, biological and nutritional properties of Synsepalum dulcificum.

Pathophysiology of hyperuricemia and its clinical significance - a narrative review

Hyperuricemia, i.e. increased serum uric acid (UA) concentration, is a common problem in clinical practice. While there are clear guidelines concerning management of symptomatic hyperuricemia in acute conditions such as gout, urolithiasis or acute urate nephropathy, less is known about their secondary prevention. Moreover, despite the ongoing debate on the role of UA in the pathogenesis of chronic kidney disease, hypertension, cardiovascular disease and heart failure, the management of asymptomatic hyperuricemia in patients with these chronic conditions is still mainly up to physicians' judgement. Individual considerations should always be taken into account when prescribing urate-lowering therapy. In this narrative review study, we attempt to present current trends concerning treatment of patients with either symptomatic or asymptomatic hyperuricemia in the light of the available knowledge on the role of hyperuricemia in the development of gout, renal, cardiovascular and other diseases.

Harnessing hyperuricemia to atherosclerosis and understanding its mechanistic dependence

Atherosclerosis is regarded as the disease of the arterial vasculature. The main characteristics of atherosclerosis are the abnormal accumulation of lipids, increased inflammatory cells, matrix deposits, and proliferation of smooth muscle cells. Diabetes mellitus, obesity, and hyperlipidemia are the most studied risk factors of atherosclerosis. One least studied risk factor is the uric acid (UA), a high UA in circulation is interlinked with many pathological processes. Several epidemiological studies suggest elevated UA levels as an essential biomarker in the forecast of several cardiovascular diseases. Available evidence claims that UA upholds the atherosclerosis process via disturbing lipid metabolism, reducing the nitric oxide synthesis in endothelial cells, promoting the proliferation of vascular smooth muscle cells, and overwhelms inflammation. In endothelial dysfunction and coronary artery lesions, UA is considered as an independent predictor. The updated studies on the involvement of hyperuricemia in atherosclerosis prove that treatment with xanthine oxidase (XO) inhibitors not just benefits the treatment of hyperuricemia but also reduces the burden of atherosclerosis to a greater extent. In this review, we highlight how the hyperuricemia affects vascular integrity, causes atherosclerosis, and the mechanism of action of XO inhibitors on atherosclerosis.

Discovery of Dotinurad (FYU-981), a New Phenol Derivative with Highly Potent Uric Acid Lowering Activity

To derive new uricosuric agents, novel phenol derivatives were synthesized to overcome the disadvantages of benzbromarone (BBR), attributed by its structural features. Herein, we report the discovery of new phenol derivatives with a 1,1-dioxo-1,2-dihydro-3H-1,3-benzothiazole scaffold. The selected compound 11 (dotinurad, FYU-981) demonstrated remarkable inhibitory activity on uric acid uptake by primary human renal proximal tubule epithelial cells (RPTECs) and URAT1-mediated uric acid transport, with weak inhibitory activity against mitochondrial respiration. Dotinurad also displayed favorable pharmacokinetic profiles and higher potency in decreasing uric acid than BBR did in Cebus monkeys. Dotinurad has been approved as a new uricosuric medicine in Japan. Our strategy, which focuses on the structural features resulting in unfavorable effects, could be applied to the future developments of other drugs with disadvantages, particularly those having a bis-aryl ketone structure.

Investigation of the Effects and Mechanisms of Dendrobium loddigesii Rolfe Extract on the Treatment of Gout

Objective

Gout is a chronic disease that causes inflammatory arthritis, which is closely related to urate accumulation induced by a disorder of uric acid metabolism and the consequent deposition of monosodium urate crystals. Dendrobium loddigesii Rolfe is an herbal medicine that has been used in some traditional Chinese medicine formulae in the treatment of gout. This study aimed to explore and verify the antigout activity of Dendrobium loddigesii extract (DLE) on alleviating the hyperuricaemia of mice and the acute gouty arthritis of rats.

Methods

An animal model of hyperuricaemia was established using potassium oxonate (PO). We analysed the expression of uric acid transporter mRNA in the kidney in the hyperuricaemic mice after treatment with DLE. Simultaneously, a monosodium urate crystal-induced acute gouty arthritis rat model was used to evaluate the effects of DLE, according to the level of ankle swelling, as well as the protein levels of inflammatory receptors and cytokines, as assayed by WB and ELISA.

Results

DLE alleviated hyperuricaemia in mice and inhibited acute gouty arthritis in rats (P < 0.05). Meanwhile, DLE regulated the levels of uric acid transporters mRNA transcripts, including mouse organic anion transporter 1 (mOAT1), organic anion transporter 3 (mOAT3), urate transporter 1 (mURAT1), and glucose transporter 9 (mGLUT9) in the kidney (P < 0.05), suggesting that DLE promoted uric acid metabolism. Furthermore, DLE significantly suppressed the protein levels of TLRs, MyD88, and NF-κB in the ankle joint's synovium (P < 0.05), and the serum levels of IL-1β, IL-6, and TNF-α were also reduced, which demonstrated the anti-inflammatory effects of DLE.

Conclusion

DLE alleviates hyperuricaemia by regulating the transcription level of uric acid transporters in the kidney. It also inhibits acute gouty arthritis by inhibiting the pathway of TLRs/MyD88/NF-κB in the ankle joint's synovium. The findings of the present study imply that DLE alleviates gout by promoting uric acid metabolism and inhibiting inflammation related to the TLRs/MyD88/NF-κB pathway.