Long-term cardiovascular safety of febuxostat compared with allopurinol in patients with gout (FAST): a multicentre, prospective, randomised, open-label, non-inferiority trial

Effects of allopurinol and febuxostat on uric acid transport and transporter expression in human umbilical vein endothelial cells

Uric acid induces radical oxygen species formation, endothelial inflammation, and endothelial dysfunction which contributes to the progression of atherosclerosis. Febuxostat inhibits BCRP- and allopurinol stimulates MRP4-mediated uric acid efflux in human embryonic kidney cells. We hypothesized that endothelial cells express uric acid transporters that regulate intracellular uric acid concentration and that modulation of these transporters by febuxostat and allopurinol contributes to their different impact on cardiovascular mortality. The aim of this study was to explore a potential difference between the effect of febuxostat and allopurinol on uric acid uptake by human umbilical vein endothelial cells. Febuxostat increased intracellular uric acid concentrations compared with control. In contrast, allopurinol did not affect intracellular uric acid concentration. In line with this observation, febuxostat increased mRNA expression of GLUT9 and reduced MRP4 expression, while allopurinol did not affect mRNA expression of these uric acid transporters. These findings provide a possible pathophysiological pathway which could explain the higher cardiovascular mortality for febuxostat compared to allopurinol but should be explored further.

Efficacy and Safety of Allopurinol and Febuxostat in Patients With Gout and CKD: Subgroup Analysis of the STOP Gout Trial

RATIONALE & OBJECTIVE

We conducted a prespecified examination of the efficacy and safety of allopurinol and febuxostat administered using a treat-to-target strategy in trial participants with chronic kidney disease (CKD).

STUDY DESIGN

Prespecified sub cohort analysis of a randomized controlled trial.

SETTING

& Participants: A sub study of the STOP Gout trial in participants with CKD. CKD was defined as an eGFR 30-59 mL/min/1.73 m2 at baseline.

EXPOSURE

Trial participants with CKD and gout and serum urate (sUA) concentration ≥6.8 mg/dL were randomized 1:1 to receive allopurinol or febuxostat. Urate lowering therapy (ULT) was titrated during weeks 0-24 to achieve a goal sUA of <6.0 mg/dl (<5.0 mg/dl with tophi) (Phase 1) and maintained during weeks 25-48 (Phase 2). Gout flare was assessed between weeks 49-72 (Phase 3).

OUTCOME

Gout flare between weeks 49-72 (Phase 3) was the primary outcome. Secondary outcomes included sUA goal achievement and ULT dosing at end of Phase 2, and serious adverse events (SAEs).

ANALYTICAL APPROACH

Outcomes between treatment groups were compared using logistic regression models for binary outcomes, and Poisson regression for flare rates. Multivariable models were subsequently used, adjusting for factors identified to be imbalanced by treatment arm.

RESULTS

351 of 940 participants (37.3%) had CKD; 277 were assessed for the primary outcome. Fewer patients randomized to allopurinol had a flare during phase 3 (32% vs 45%; p=0.02) despite similar attainment of sUA goal (79% vs. 81%; p=0.6) by the end of Phase 2. Acute kidney injury (AKI) was more common in participants with stage 3 CKD randomized to allopurinol compared to febuxostat.

LIMITATIONS

Limited power to assess infrequent safety events, largely male, older population.

CONCLUSIONS

Allopurinol and febuxostat are similarly efficacious and well-tolerated in the treatment of gout in people with CKD when used in a treat-to-target regimen.

Lactococcus cremoris D2022 alleviates hyperuricemia and suppresses renal inflammation via potential gut-kidney axis

Hyperuricemia (HUA) is a widespread metabolic disorder. Probiotics have drawn increasing attention as an adjunctive treatment with fewer side effects. However, thus far the effective strains are limited and the mechanisms for their serum uric acid (SUA)-lowering effect are not well understood. Along this line, we conducted the current study using a hyperuricemia mouse model induced by potassium oxonate and adenine. A novel strain of Lactococcus cremoris named D2022 was identified to have significant SUA-lowering capability. Lactococcus cremoris D2022 significantly reduced SUA levels by inhibiting uric acid synthesis and regulating uric acid transportation. It was also found that Lactococcus cremoris D2022 alleviated HUA-induced renal inflammatory injury involving multiple signaling pathways. By focusing on the expression of NLRP3-related inflammatory genes, we found correlations between the expression levels of these genes and free fatty acid receptors (FFARs). In addition, oral administration of Lactococcus cremoris D2022 increased short-chain fatty acids (SCFAs) in cecal samples, which may be one of the mechanisms by which oral probiotics alleviate renal inflammation. Serum untargeted metabolomics showed changes in a variety of serum metabolites associated with purine metabolism and inflammation after oral administration of Lactococcus cremoris D2022, further confirming its systemic bioactivity. Finally, it was proved that Lactococcus cremoris D2022 improved intestinal barrier function. In conclusion, Lactococcus cremoris D2022 can alleviate HUA and HUA-induced nephropathy by increasing the production of SCFAs in the gut and systemic metabolism.

Discovery of digallic acid as XOD/URAT1 dual target inhibitor for the treatment of hyperuricemia

The development of XOD/URAT1 dual target inhibitors has emerged as a promising therapeutic strategy for the management of hyperuricemia. Here, through virtual screening, we have identified digallic acid as a novel dual target inhibitor of XOD/URAT1 and subsequently evaluated its pharmacological properties, pharmacokinetics, and toxicities. Digallic acid inhibited URAT1 with an IC50 of 5.34 ± 0.65 μM, which is less potent than benzbromarone (2.01 ± 0.36 μM) but more potent than lesinurad (10.36 ± 1.23 μM). Docking and mutation analysis indicated that residues S35, F241 and R477 of URAT1 confer a high affinity for digallic acid. Digallic acid inhibited XOD with an IC50 of 1.04 ± 0.23 μM. Its metabolic product, gallic acid, inhibited XOD with an IC50 of 0.91 ± 0.14 μM. Enzyme kinetic studies indicated that both digallic acid and gallic acid act as mixed-type XOD inhibitors. It shares the same binding mode as digallic acid, and residues E802, R880, F914, T1010, N768 and F1009 contribute to their high affinity. The anion group (carboxyl) of digallic acid contribute significantly to its inhibition activity on both XOD and URAT1 as indicated by docking analysis. Remarkably, at a dosage of 10 mg/kg in vivo, digallic acid exhibited a stronger urate-lowering and uricosuric effect compared to the positive drug benzbromarone and lesinurad. Pharmacokinetic study indicated that digallic acid can be hydrolyzed into gallic acid in vivo and has a t1/2 of 0.77 ± 0.10 h. Further toxicity evaluation indicated that digallic acid exhibited no obvious renal toxicity, as reflected by CCK-8, biochemical analysis (CR and BUN) and HE examination. The findings of our study can provide valuable insights for the development of XOD/URAT1 dual target inhibitors, and digallic acid deserves further investigation as a potential anti-hyperuricemic drug.

Impacts of Febuxostat on Cerebral and Cardiovascular Events in Elderly Patients with Hyperuricemia: Post Hoc Analysis of a Randomized Controlled Trial

A recent meta-analysis found no benefit of uric acid-lowering therapy including febuxostat on death, cardiovascular events, or renal impairment. However, there may be populations that benefit from febuxostat in reducing mortality and cerebral and cardiovascular events. The aim of the present study was to examine the clinical benefit of febuxostat in elderly patients stratified by age using Febuxostat for Cerebral and CaRdiorenovascular Events PrEvEntion StuDy (FREED) data. FREED was a randomized study involving patients aged 65 years or older with hyperuricemia and risk factors for cerebral, cardiovascular, or renal diseases. A total of 1,070 patients were included in this post hoc analysis, divided into 2 age groups: 65-74 years and ≥ 75 years. Patients were randomized into febuxostat and non-febuxostat groups, with uric acid levels monitored for 36 months. The primary composite end point included cerebral, cardiovascular, and renal events. In patients aged between 65 and 74 years, febuxostat significantly reduced the risk of future cerebral and cardiorenovascular events. However, no effects of febuxostat were found in the older population aged ≥ 75 years. Heterogeneity in potential interactions between the age and febuxostat treatment was particularly observed in non-fatal cerebral and cardiovascular events and all-cause death. Patients aged ≥ 75 years exhibited more pre-existing factors associated with cerebral and cardiorenovascular events than those aged 65-74 years. The effectiveness of febuxostat varies by age group, with potential benefits for patients aged 65-74 years. The effects of febuxostat are complex and it is important to consider patient characteristics in its clinical use.

Analyzing chemical composition of Sargentodoxae caulis water extract and their hypouricemia effect in hyperuricemic mice

Hyperuricemia (HUA) is a metabolic disease characterized by the increase of serum uric acid (UA) level. Sargentodoxae Caulis (SC) is a commonly used herbal medicine for the treatment of gouty arthritis, traumatic swelling, and rheumatic arthritis in clinic. In this study, a total of fifteen compounds were identified in SC water extract using UHPLC-Q-TOF-MS/MS, including three phenolic acids, seven phenolic glycosides, four organic acids, and one lignan. Then, to study the hypouricemia effect of SC, a HUA mouse model was induced using a combination of PO, HX, and 20% yeast feed. After 14 days of treatment with the SC water extract, the levels of serum UA, creatinine (CRE), blood urea nitrogen (BUN) were reduced significantly, and the organ indexes were restored, the xanthine oxidase (XOD) activity were inhibited as well. Meanwhile, SC water extract could ameliorate the pathological status of kidneys and intestine of HUA mice. Additionally, quantitative real-time PCR (qRT-PCR) and western blotting results showed that SC water extract could increase the expression of ATP binding cassette subfamily G member 2 (ABCG2), organic cation transporter 1 (OCT1), organic anion transporter 1 (OAT1) and organic anion transporter 3 (OAT3), whereas decrease the expression of glucose transporter 9 (GLUT9). This study provided a data support for the clinical application of SC in the treatment of HUA.

Gout and its management

Gout is a common and treatable chronic disease of monosodium urate crystal deposition. It is experienced as extremely painful episodes of joint inflammation that impact all aspects of the person's life. This Clinical Perspectives article provides an update on gout diagnosis, medications and strategies to improve the quality of gout care.

Superiority of Low-Dose Benzbromarone Add-On to Low-Dose Febuxostat Compared With Febuxostat Monotherapy in Gout With Combined-Type Hyperuricemia

OBJECTIVE

There is an unmet need for simpler urate-lowering therapy (ULT) regimens that achieve the serum urate target and improve the overall quality of gout care. We report a comparative effectiveness trial of febuxostat monotherapy versus benzbromarone add-on to low-dose febuxostat in gout specifically with combined renal urate underexcretion and overload.

METHODS

A prospective randomized trial was conducted on patients with combined-type hyperuricemia and estimated glomerular filtration rate >60 mL/min/1.73 m2 1:1 randomly assigned to febuxostat and benzbromarone combination therapy (initially febuxostat at 20 mg/day, with benzbromarone at 25 mg/day added onto 20 mg/day of febuxostat if not at target) or febuxostat monotherapy (initially 20 mg/day, escalating to 40 mg/day if not at target). The primary end point at 12 weeks was the proportion achieving a serum urate (SU) level <360 μmol/L. Other outcomes included altered liver and kidney function, new-onset urolithiasis, and gout flares.

RESULTS

There were 250 participants randomized; 219 completed 12-week treatment. More patients in the febuxostat and benzbromarone combination group achieved the SU target compared to patients in the febuxostat monotherapy group (75.5% vs 47.7%; odds ratio 3.37 [95% confidence interval 1.90-5.98]). Safety profiles were comparable between the two groups.

CONCLUSION

Simply adding on low-dose benzbromarone (25 mg/day) to low-dose (20 mg/day) febuxostat showed superior urate lowering compared to febuxostat monotherapy in gout with a combined-type hyperuricemia. For selected patients, expedited achievement of the SU target in more than 75% of patients using one titration step and low xanthine oxidase inhibitor and uricosuric doses is a potential alternative to standard ULT regimens.

Unclosing Premature Mortality Gap Among Patients With Gout in the US General Population, Independent of Serum Urate and Atherosclerotic Cardiovascular Risk Factors

OBJECTIVE

Gout flares are followed by transient major cardiovascular (CV) risk, implicating the role of inflammation; the aim of this study was to determine whether premature mortality rates in patients with gout and CV risk are independent of serum urate (SU) and atherosclerotic CV disease (ASCVD) risk factors.

METHODS

Using serial US nationwide prospective cohorts, we evaluated the independent association of prevalent gout with all-cause and CV mortality, adjusting for SU, ASCVD risk factors, comorbidities, medications, and kidney function and compared mortality rates between the early (1988-1994 baseline) and late cohorts (2007-2016 baseline). We replicated late cohort findings among patients with gout in a nationwide UK cohort (2006-2010 baseline).

RESULTS

Adjusted hazard ratios (HRs) for mortality rates in patients with prevalent gout were similar in early and late US cohorts (1.20 [1.03-1.40] and 1.19 [1.04-1.37], respectively); HRs with further adjustment for SU were 1.19 (1.02-1.38) and 1.19 (1.03-1.37), respectively. Adjusted HR among patients with gout from the UK late cohort was 1.61 (1.47-1.75); these associations were larger among women (P = 0.04) and prominent among Black individuals. Adjusted HR for CV mortality rates in the late US cohort was 1.39 (1.09-1.78); those for circulatory, CV, and coronary heart disease deaths among UK patients with incident gout were 1.48 (1.24-1.76), 1.49 (1.20-1.85), and 1.59 (1.26-1.99), respectively.

CONCLUSIONS

Patients with gout experience a persistent mortality gap in all-cause and CV deaths, even adjusting for SU and ASCVD risk factors, supporting a role for gout-specific pathways (eg, flare inflammation). These findings suggest gaps in current care, particularly in women and possibly among Black patients.

Comparison of the therapeutic effects of febuxostat combined with a low-purine diet and allopurinol combined with a low-purine diet on the improvement of gout patients

OBJECTIVE

To compare the clinical efficacy of febuxostat combined with a low-purine diet versus allopurinol combined with a low-purine diet in the treatment of gout.

METHODS

In this prospective controlled trial, 98 gout patients admitted to our hospital from February 2021 to December 2022 were enrolled as study subjects. Patients were randomly assigned to the study group (febuxostat combined with a low-purine diet) and the control group (allopurinol combined with a low-purine diet), with 49 patients in each group. The therapeutic effect was evaluated based on joint function and serum uric acid levels after treatment, and classified into three levels: markedly effective, effective, and ineffective. The levels of inflammatory factors, including tumor necrosis factor-a (TNF-a), cytokine interleukin-1beta (IL-1β), and interleukin (IL)-18 (IL-18), were collected. The Numeric Rating Scale (NRS) was used to assess the degree of pain in patients. Clinical indicators before and 6 months after treatment were compared between the two groups.

RESULTS

There was no statistically significant difference in age and gender between the two groups. After 6 months of treatment, the effective rate in the study group (48 cases, 97.96%) was higher than that in the control group (42 cases, 85.71%), with a statistically significant difference (p = .027). At the same time, the study group had significantly lower levels of serum uric acid (162.39 μmol/L ± 17.23 μmol/L vs. S198.32 μmol/L ± 18.34 μmol/L, p < .001), creatinine (87.39 mmol/L ± 9.76 mmol/L vs. 92.18 mmol/L ± 9.27 mmol/L, p = .014), total cholesterol (3.65 mmol/L ± 0.65 mmol/L vs. 4.76 mmol/L ± 0.73 mmol/L, p < .001), and triglycerides (1.76 mmol/L ± 0.32 mmol/L vs. 2.28 mmol/L ± 0.41 mmol/L, p < .001) compared to the control group, with statistically significant differences (p < .05). After treatment, the levels of inflammatory factors and degree of pain in the study group were significantly lower than those in the control group (all p < .05). During the treatment process, the incidence of adverse reactions in the study group (2 cases, 4.08%) was lower than that in the control group (9 cases, 18.37%), with a statistically significant difference (p = .025).

CONCLUSION

Febuxostat combined with a low-purine diet can reduce inflammatory factors and alleviate the degree of pain in gout patients, significantly improving their clinical symptoms.

Combination Treatment with Verinurad and Allopurinol in CKD: A Randomized Placebo and Active Controlled Trial

Key Points

The SAPPHIRE trial was designed to assess albuminuria-lowering effects of the urate transporter 1 inhibitor verinurad combined with allopurinol in patients with CKD. Verinurad 3, 7.5, and 12 mg in combination with allopurinol 300 mg did not reduce albuminuria during 34 weeks treatment compared with allopurinol alone or placebo. Verinurad/allopurinol combination dose-dependently reduced serum urate concentrations compared with placebo.

Background

Hyperuricemia is associated with elevated risks of cardiovascular and chronic kidney disease (CKD). Since inhibition of urate transporter 1 has been suggested to be potentially nephroprotective, we performed a phase 2b study to assess albuminuria-lowering effects of the urate transporter 1 inhibitor verinurad combined with the xanthine oxidase inhibitor allopurinol in patients with CKD and hyperuricemia.

Methods

In this randomized placebo and active controlled trial, we enrolled participants with serum urate concentrations ≥6.0 mg/dl, eGFR ≥25 ml/min per 1.73 m2, and a urinary albumin-creatinine ratio (UACR) 30–5000 mg/g to one of five treatment arms: placebo, placebo+allopurinol 300 mg/day, verinurad 3 mg+allopurinol 300 mg/day, verinurad 7.5 mg+allopurinol 300 mg/day, or verinurad 12 mg+allopurinol 300 mg/day in a 1:1:1:1:1 ratio. The primary end point was the change in UACR from baseline to 34 weeks. Secondary end points were changes from baseline in UACR at week 60 and changes in serum urate and eGFR at weeks 34 and 60.

Results

Between August 2019 and November 2021, 861 adults with CKD (mean age 65 years, 33.0% female, mean eGFR 48 ml/min per 1.73 m2, median UACR 217 mg/g) were enrolled. At 34 weeks, the geometric mean percentage change in UACR from baseline did not differ among treatment groups (16.7%, 95% confidence interval [CI], −0.6 to 37.1 in the 3 mg group, 15.0% [95% CI, −1.85 to 34.6] in the 7.5 mg group, 14.0% [95% CI, −3.4 to 34.4] in the 12 mg group versus 9.9% [95% CI, −6.6 to 29.4] in the allopurinol group, and 37.3% [95% CI, 16.6 to 61.8] in the placebo group). UACR and eGFR change from baseline did not differ among treatment groups after 60 weeks. Verinurad/allopurinol combination dose-dependently reduced serum urate concentrations compared with placebo. The proportion of patients with adverse events and serious adverse events was balanced among treatment groups.

Conclusions

Verinurad in combination with allopurinol did not decrease UACR or eGFR decline, but further reduced serum urate compared with allopurinol alone or placebo.

Clinical Trial registry name and registration number:

SAPPHIRE Trial registration number, NCT03990363 .

Timing of Initiation of Xanthine Oxidase Inhibitors Based on Serum Uric Acid Level Does Not Predict Renoprognosis in Patients with Preserved Kidney Function

Background: Despite recent evidence of remaining possibility that early initiation of xanthine oxidase inhibitors (XOIs) is beneficial in renoprognosis for patients with stage 2 or less chronic kidney disease (CKD), no evidence is available regarding the difference in renoprognosis based on serum uric acid (sUA) levels at the initiation of XOIs among patients with preserved kidney function. Methods: New XOI initiators were divided into quartiles based on baseline sUA. Primary outcome was the composite incidence of a significant estimated glomerular filtration rate (eGFR) decline (≥40% decline in eGFR from baseline or development of eGFR <30 mL/1.73 m2/min) or all-cause death within 5 years. Results: After excluding inapplicable patients, 1170 XOI initiators were analyzed (mean ± standard deviation age: 68 ± 14.3 years; sUA: 10.6 ± 1.15 mg/dL). On overall median [interquartile range (IQR)] follow-up of 824 (342, 1576) days, incidence rate of the primary outcome was 287 per 1000 person-years for 5 years. Although the nonadjusted model showed a dose-response association between baseline sUA level and the outcome, the adjusted model showed no significant association. Adjusted hazard ratios (95% confidence interval) of the second, third, and fourth quartiles of baseline sUA with the composite outcome within 5 years compared to the first quartile were 1.00 (0.78, 1.29), 1.00 (0.80, 1.30), and 1.02 (0.80, 1.32), respectively. Conclusions: Early initiation of XOIs did not predict a significant benefit on renoprognosis even among the population with preserved kidney function. The validity of initiating XOIs with the aim of improving renoprognosis based on sUA is questionable.

The Effects of Pharmacological Urate-Lowering Therapy on Cardiovascular Disease in Older Adults with Gout

Cardiovascular disease is an important cause of mortality in older patients. In addition to the traditional risk factors for cardiovascular disease, hyperuricemia has been increasingly associated with an elevated risk of cardiovascular disease. Uric acid itself has several unfavorable effects on the cardiovascular system, and hyperuricemia can lead to the development of gout. Gout is the most prevalent inflammatory rheumatic disease. Older patients with gout have an increased risk of cardiovascular morbidity and mortality due to an increased prevalence of traditional risk factors, as well as the inflammatory burden of gout activity. As the prevalence of traditional risk factors and the prevalence of both hyperuricemia and gout are increasing in older adults, cardiovascular risk management in these patients is very important. This risk management consists of, on the one hand, treatment of individual traditional risk factors and, on the other hand, of urate lowering, thereby decreasing inflammatory burden of gout. However, there is insufficient evidence to conclude that urate-lowering therapy reduces the risk of cardiovascular events. Moreover, from a cardiovascular point of view, there is no preference for one urate lowering drug over another in patients with gout, nor is there enough evidence to support a preference in patients with gout with increased cardiovascular risk. Personalized treatment in older patients with gout should be aimed at optimizing serum uric acid levels, as well as targeting traditional cardiovascular risk factors. Further prospective randomized trials are needed to support the hypothesis that urate lowering reduces cardiovascular risk in older patients with gout.

The clinical benefits of sodium-glucose cotransporter type 2 inhibitors in people with gout

Gout is the most common form of inflammatory arthritis worldwide and is characterized by painful recurrent flares of inflammatory arthritis that are associated with a transiently increased risk of adverse cardiovascular events. Furthermore, gout is associated with multiple cardiometabolic-renal comorbidities such as type 2 diabetes, chronic kidney disease and cardiovascular disease. These comorbidities, potentially combined with gout flare-related inflammation, contribute to persistent premature mortality in gout, independently of serum urate concentrations and traditional cardiovascular risk factors. Although better implementation of standard gout care could improve gout outcomes, deliberate efforts to address the cardiovascular risk in patients with gout are likely to be required to reduce mortality. Sodium-glucose cotransporter type 2 (SGLT2) inhibitors are approved for multiple indications owing to their ability to lower the risk of all-cause and cardiovascular death, hospitalizations for heart failure and chronic kidney disease progression, making them an attractive treatment option for gout. These medications have also been shown to lower serum urate concentrations, the causal culprit in gout risk, and are associated with a reduced risk of incident and recurrent gout, potentially owing to their purported anti-inflammatory effects. Thus, SGLT2 inhibition could simultaneously address both the symptoms of gout and its comorbidities.

Uric acid in health and disease: From physiological functions to pathogenic mechanisms

Owing to renal reabsorption and the loss of uricase activity, uric acid (UA) is strictly maintained at a higher physiological level in humans than in other mammals, which provides a survival advantage during evolution but increases susceptibility to certain diseases such as gout. Although monosodium urate (MSU) crystal precipitation has been detected in different tissues of patients as a trigger for disease, the pathological role of soluble UA remains controversial due to the lack of causality in the clinical setting. Abnormal elevation or reduction of UA levels has been linked to some of pathological status, also known as U-shaped association, implying that the physiological levels of UA regulated by multiple enzymes and transporters are crucial for the maintenance of health. In addition, the protective potential of UA has also been proposed in aging and some diseases. Therefore, the role of UA as a double-edged sword in humans is determined by its physiological or non-physiological levels. In this review, we summarize biosynthesis, membrane transport, and physiological functions of UA. Then, we discuss the pathological involvement of hyperuricemia and hypouricemia as well as the underlying mechanisms by which UA at abnormal levels regulates the onset and progression of diseases. Finally, pharmacological strategies for urate-lowering therapy (ULT) are introduced, and current challenges in UA study and future perspectives are also described.

The Terminalia chebula Retz extract treats hyperuricemic nephropathy by inhibiting TLR4/MyD88/NF-κB axis

ETHNOPHARMACOLOGICAL RELEVANCE

Hyperuricemic nephropathy (HN) is a renal injury caused by hyperuricemia and is the main cause of chronic kidney disease and end-stage renal disease. ShiWeiHeZiSan, which is composed mainly of components of Terminalia chebula Retz. And is recorded in the Four Medical Tantras, is a typical traditional Tibetan medicinal formula for renal diseases. Although T. chebula has been reported to improve renal dysfunction and reduce renal cell apoptosis, the specific mechanism of the nephroprotective effects of T. chebula on HN is still unclear.

AIM OF THE STUDY

This study was conducted to evaluate the effects and specific mechanism of T. chebula extract on HN through network pharmacology and in vivo and in vitro experiments.

MATERIALS AND METHODS

Potassium oxalate (1.5 g/kg) and adenine (50 mg/kg) were combined for oral administration to establish the HN rat model, and the effects of T. chebula extract on rats in the HN model were evaluated by renal function indices and histopathological examinations. UPLC-Q-Exactive Orbitrap/MS analysis was also conducted to investigate the chemical components of T. chebula extract, and the potential therapeutic targets of T. chebula in HN were predicted by network pharmacology analysis. Moreover, the activation of potential pathways and the expression of related mRNAs and proteins were further observed in HN model rats and uric acid-treated HK-2 cells.

RESULTS

T. chebula treatment significantly decreased the serum uric acid (SUA), blood urea nitrogen (BUN) and serum creatinine (SCr) levels in HN rats and ameliorated renal pathological injury and fibrosis. A total of 25 chemical components in T. chebula extract were identified by UPLC-Q-Exactive Orbitrap/MS analysis, and network pharmacology analysis indicated that the NF-κB pathway was the potential pathway associated with the therapeutic effects of T. chebula extract on HN. RT‒PCR analysis, immunofluorescence staining and ELISA demonstrated that the mRNA and protein levels of TLR4 and MyD88 were significantly decreased in the renal tissue of HN rats after treatment with T. chebula extract at different concentrations, while the phosphorylation of P65 and the secretion of TNF-α and IL-6 were significantly inhibited. The results of in vitro experiments showed that T. chebula extract significantly decreased the protein levels of TLR4, MyD88, p-IκBα and p-P65 in uric acid-treated HK-2 cells and inhibited the nuclear translocation of p65 in these cells. In addition, the expression of inflammatory factors (IL-1β, IL-6 and TNF-α) and fibrotic genes (α-SMA and fibronectin) was significantly downregulated by T. chebula extract treatment, while E-cadherin expression was significantly upregulated.

CONCLUSION

T. chebula extract exerts nephroprotective effects on HN, such as anti-inflammatory effects and fibrosis improvement, by regulating the TLR4/MyD88/NF-κB axis, which supports the general use of T. chebula in the management of HN and other chronic kidney diseases.

Impact of Hyperuricemia and Urate-Lowering Agents on Cardiovascular Diseases

The association between hyperuricemia and cardiovascular diseases has been studied for many years. Research has shown a link between high uric acid levels and increased risk of including coronary artery disease hypertension and other cardiovascular conditions. Urate-lowering therapy, particularly with xanthine oxidase inhibitors like allopurinol, has shown promising results in reducing blood pressure in individuals with hyperuricemia and hypertension. Clinical trials and studies have demonstrated significant reductions in both systolic and diastolic blood pressure with urate-lowering treatment. Urate-lowering treatment has shown a favorable effect on reducing systolic blood pressure and major adverse cardiovascular events in patients with previous cardiovascular disease. In terms of cardiovascular safety, clinical trials have indicated that xanthine oxidase inhibitors such as febuxostat are non-inferior to allopurinol and do not increase the risk of death or serious adverse events. Overall, these findings highlight the importance of managing hyperuricemia and utilizing urate-lowering therapy to mitigate the adverse cardiovascular effects associated with elevated uric acid levels.

Targeting Neutrophil Extracellular Traps in Gouty Arthritis: Insights into Pathogenesis and Therapeutic Potential

Gouty arthritis (GA) is an immune-mediated disorder characterized by severe inflammation due to the deposition of monosodium urate (MSU) crystals in the joints. The pathophysiological mechanisms of GA are not yet fully understood, and therefore, the identification of effective therapeutic targets is of paramount importance. Neutrophil extracellular traps (NETs), an intricate structure of DNA scaffold, encompassing myeloperoxidase, histones, and elastases - have gained significant attention as a prospective therapeutic target for gouty arthritis, due to their innate antimicrobial and immunomodulatory properties. Hence, exploring the therapeutic potential of NETs in gouty arthritis remains an enticing avenue for further investigation. During the process of gouty arthritis, the formation of NETs triggers the release of inflammatory cytokines, thereby contributing to the inflammatory response, while MSU crystals and cytokines are sequestered and degraded by the aggregation of NETs. Here, we provide a concise summary of the inflammatory processes underlying the initiation and resolution of gouty arthritis mediated by NETs. Furthermore, this review presents an overview of the current pharmacological approaches for treating gouty arthritis and summarizes the potential of natural and synthetic product-based inhibitors that target NET formation as novel therapeutic options, alongside elucidating the intrinsic challenges of these inhibitors in NETs research. Lastly, the limitations of HL-60 cell as a suitable substitute of neutrophils in NETs research are summarized and discussed. Series of recommendations are provided, strategically oriented towards guiding future investigations to effectively address these concerns. These findings will contribute to an enhanced comprehension of the interplay between NETs and GA, facilitating the proposition of innovative therapeutic strategies and novel approaches for the management of GA.

Relationship between hyperuricemia and the risk of cardiovascular events and chronic kidney disease in both the general population and hypertensive patients: A systematic review and meta-analysis

BACKGROUND

To explore the relationships between hyperuricemia and the risk of cardiovascular diseases (CVD) and chronic kidney disease (CKD) in both the general population and hypertensive patients through meta-analysis.

METHODS AND RESULTS

We systematically searched PubMed, Embase, and Cochrane Library databases from January 2012. The eligibility criteria were predefined, and quality was assessed using the Newcastle-Ottawa Scale (NOS). Stata 15.1 was used for meta-analysis, heterogeneity and sensitivity analysis. Subgroup analysis was used to explore heterogeneity, funnel plots and Egger tests were used to assesse publication bias and applicability. A total of 10,662 studies were retrieved, 45 of which were included in this meta-analysis utilizing a random effects model. Hyperuricemia was significantly associated with an increased risk of new-onset hypertension (RR = 1.36, 95% CI 1.16-1.59; I2 = 98.8%), total CVD (RR = 1.53, 95% CI 1.23-1.89; I2 = 93.7%), stroke (RR = 1.97, 95% CI 1.71-2.26, I2 = 0.0%), coronary heart disease (CHD) (RR = 1.56, 95% CI 1.06-2.30, I2 = 93.3%), and CKD (RR = 1.71, 95% CI 1.56-1.87; I2 = 87.3%). However, subgroup analysis showed no significant associations between hyperuricemia and hypertension in non-Asian populations (RR = 0.88, 95% CI 0.59-1.33), or between hyperuricemia and CVD with a follow-up duration <5 years (RR = 1.26, 95% CI 0.97-1.63). Among hypertensive patients, hyperuricemia was significantly associated with total CVD (RR = 2.32, 95% CI 1.31-4.12, I2 = 90.2%), but not with stroke (RR = 1.48, 95% CI 0.86-2.55; I2 = 90.7%) or CHD (RR = 1.51, 95% CI 0.98-2.33; I2 = 71.7%).

CONCLUSION

Hyperuricemia was significantly associated with an increased risk of new-onset hypertension, total CVD, stroke, CHD, and CKD in the general population. Among hypertensive patients, hyperuricemia was associated with an increased risk of CVD but not stroke or CHD alone.

REGISTRATION NUMBER

CRD42022370692.

Cardiovascular Safety of Febuxostat in Patients With Gout or Hyperuricemia: A Systematic Review of Randomized Controlled Trials

INTRODUCTION

To this date, a causal relationship between febuxostat and cardiovascular disease remains controversial as comparison between trials can be challenging and may lead to misleading conclusions, especially when facing heterogeneous cardiovascular outcomes. We aimed to compare the cardiovascular outcomes in the most pertinent trials of febuxostat compared with controls.

METHODS

We searched electronic databases using a PICOS-style approach search strategy of randomized controlled trials (RCTs) on cardiovascular outcomes of febuxostat in patients with gout or hyperuricemia. We conducted a quality and risk of bias assessment of the included clinical trials. The definition of major adverse cardiovascular event as well as all reported cardiovascular outcomes were retrieved from every involved trial.

RESULTS

Of the 1173 records identified from all sources, 20 RCTs were included in the analysis. The mean duration of follow-up was 69.7 ± 81.5 weeks, and febuxostat dose ranged from 10 to 240 mg with 80 mg being the most commonly used dosage. Overall, the quality of evidence deriving from all RCTs showed concerns in most studies (65%). Major adverse cardiovascular event was defined in 7 of the 20 RCTs (35%), and cardiovascular outcome reporting was very heterogeneous. Overall, the data of cardiovascular safety of febuxostat were reassuring.

CONCLUSIONS

Our systematic review showed high level of concerns in quality assessment domains as well heterogeneous cardiovascular outcomes across included studies. Cardiovascular outcomes in the majority of White males with gout treated with febuxostat were reassuring when compared with allopurinol. Further studies are needed to draw conclusions in patients with severe cardiovascular disease.

Pathophysiology and Treatment of Gout Arthritis; including Gout Arthritis of Hip Joint: A Literature Review

Gout is triggered by the accumulation of uric acid in the body, leading to hyperuricemia. Genetic, metabolic, and environmental factors can influence this condition. Excessive uric acid buildup results in the formation of monosodium urate (MSU) crystals, which precipitate in specific areas of the body, including the joints, where they can cause symptoms of gout. While the acute and chronic symptoms of gout have been well-documented, diagnosis of gout affecting the hip joint poses significant challenges. The global incidence of gout, the most prevalent form of inflammatory arthritis, is on the rise. Evaluation of the clinical signs, laboratory results, and imaging results is generally required for diagnosis of gout in cases where MSU crystals have not been detected. Hyperuricemia is considered a primary cause of arthritis symptoms, and comprehensive guidelines for treatment are available. Therefore, the choice of medication is straightforward, and moderate effectiveness of treatment has been demonstrated. Gout is a chronic disease, requiring lifelong uric acid-lowering medications, thus application of a treatment strategy based on the target blood uric acid concentration is necessary. Consequently, cases of gout will likely be observed more frequently by hip surgeons in clinical scenarios in the future. The objective of this review is to provide an overview of the pathophysiology of gout and subsequently examine recent advances in diagnostic methods and therapeutic agents based on an understanding of its underlying mechanisms. In addition, literature on gout-related issues affecting the hip joint, providing a useful reference for hip surgeons is examined.

Allopurinol and cardiovascular outcomes in patients with ischaemic heart disease: the ALL-HEART RCT and economic evaluation

Background

Allopurinol is a xanthine oxidase inhibitor that lowers serum uric acid and is used to prevent acute gout flares in patients with gout. Observational and small interventional studies have suggested beneficial cardiovascular effects of allopurinol.

Objective

To determine whether allopurinol improves major cardiovascular outcomes in patients with ischaemic heart disease.

Design

Prospective, randomised, open-label, blinded endpoint multicentre clinical trial.

Setting

Four hundred and twenty-four UK primary care practices.

Participants

Aged 60 years and over with ischaemic heart disease but no gout.

Interventions

Participants were randomised (1 : 1) using a central web-based randomisation system to receive allopurinol up to 600 mg daily that was added to usual care or to continue usual care.

Main outcome measures

The primary outcome was the composite of non-fatal myocardial infarction, non-fatal stroke or cardiovascular death. Secondary outcomes were non-fatal myocardial infarction, non-fatal stroke, cardiovascular death, all-cause mortality, hospitalisation for heart failure, hospitalisation for acute coronary syndrome, coronary revascularisation, hospitalisation for acute coronary syndrome or coronary revascularisation, all cardiovascular hospitalisations, quality of life and cost-effectiveness. The hazard ratio (allopurinol vs. usual care) in a Cox proportional hazards model was assessed for superiority in a modified intention-to-treat analysis.

Results

From 7 February 2014 to 2 October 2017, 5937 participants were enrolled and randomised to the allopurinol arm (n = 2979) or the usual care arm (n = 2958). A total of 5721 randomised participants (2853 allopurinol; 2868 usual care) were included in the modified intention-to-treat analysis population (mean age 72.0 years; 75.5% male). There was no difference between the allopurinol and usual care arms in the primary endpoint, 314 (11.0%) participants in the allopurinol arm (2.47 events per 100 patient-years) and 325 (11.3%) in the usual care arm (2.37 events per 100 patient-years), hazard ratio 1.04 (95% confidence interval 0.89 to 1.21); p = 0.65. Two hundred and eighty-eight (10.1%) participants in the allopurinol arm and 303 (10.6%) participants in the usual care arm died, hazard ratio 1.02 (95% confidence interval 0.87 to 1.20); p = 0.77. The pre-specified health economic analysis plan was to perform a 'within trial' cost-utility analysis if there was no statistically significant difference in the primary endpoint, so NHS costs and quality-adjusted life-years were estimated over a 5-year period. The difference in costs between treatment arms was +£115 higher for allopurinol (95% confidence interval £17 to £210) with no difference in quality-adjusted life-years (95% confidence interval -0.061 to +0.060). We conclude that there is no evidence that allopurinol used in line with the study protocol is cost-effective.

Limitations

The results may not be generalisable to younger populations, other ethnic groups or patients with more acute ischaemic heart disease. One thousand six hundred and thirty-seven participants (57.4%) in the allopurinol arm withdrew from randomised treatment, but an on-treatment analysis gave similar results to the main analysis.

Conclusions

The ALL-HEART study showed that treatment with allopurinol 600 mg daily did not improve cardiovascular outcomes compared to usual care in patients with ischaemic heart disease. We conclude that allopurinol should not be recommended for the secondary prevention of cardiovascular events in patients with ischaemic heart disease but no gout.

Future work

The effects of allopurinol on cardiovascular outcomes in patients with ischaemic heart disease and co-existing hyperuricaemia or clinical gout could be explored in future studies.

Trial registration

This trial is registered as EU Clinical Trials Register (EudraCT 2013-003559-39) and ISRCTN (ISRCTN 32017426).

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 11/36/41) and is published in full in Health Technology Assessment; Vol. 28, No. 18. See the NIHR Funding and Awards website for further award information.

Cardiovascular safety of febuxostat versus allopurinol among the Asian patients with or without gout: A systematic review and meta-analysis

The cardiovascular (CV) safety of febuxostat compared to allopurinol for the treatment of hyperuricemia among Asian patients is uncertain. In this study, we conducted a systematic review and meta-analysis to compare the CV safety profiles of febuxostat with allopurinol in Asian patients with hyperuricemia. A total of 13 studies were included. On the basis of the pooled results of cohort studies, febuxostat users were at a significantly higher risk for acute coronary syndrome (ACS; hazard ratio [HR]: 1.06, 95% confidence interval [CI]: 1.03-1.09, p < 0.01), atrial fibrillation (HR: 1.19, 95% CI: 1.05-1.35, p < 0.01) than allopurinol users, whereas no significant difference between febuxostat and allopurinol existed for urgent coronary revascularization (HR: 1.07, 95% CI: 0.98-1.16, p = 0.13), and stroke (HR: 0.96, 95% CI: 0.91-1.01, p = 0.13). Nevertheless, that difference in results of acute decompensated heart failure (ADHF; HR: 0.73, 95% CI: 0.35-1.53, p = 0.40) and all-cause death (HR = 0.86, 95% CI: 0.49-1.51, p = 0.60) was not significant based on randomized controlled trials. In the Chinese subgroup, febuxostat could increase the risk of ADHF (HR: 1.22, 95% CI: 1.01-1.48, p < 0.05), CV death (HR: 1.25, 95% CI: 1.03-1.50, p < 0.05), and all-cause mortality (HR: 1.07, 95% CI: 1.01-1.14, p < 0.05) compared to allopurinol. In conclusion, the use of febuxostat, compared with allopurinol among Asian patients, was associated with a significantly increased risk of adverse CV events.

[Gout, beyond the joint: How should we treat it?]

Gout is a disease caused by the chronic deposition of monosodium urate crystals. Its clinical presentation as an acute, self-limiting arthritis and the belief that it is a banal, self-inflicted disease have led to its poor management. Despite advances in the knowledge of the disease and the simplicity of its management, no more than 30% of patients are well treated. In Spain, the prevalence of gout is 2.5% and its incidence is increasing. In the following article we will review the pathogenesis of gout and hyperuricaemia, highlighting the greater weight of genetics and renal function over diet. We will look at the consequences of crystal deposition. Gout, in addition to its joint presentation and renal involvement, has been shown to be an independent cardiovascular risk factor. Hypouricemic therapy is the most important treatment, as it is the one that dissolves the crystals and cures the disease. This requires the sustained achievement of uricemia levels below 6mg/dl. We will also review preventive and flares treatment, as well as the role of patient education in terms of both lifestyle and dietary habits and adherence to pharmacological treatment.

Effects of uric acid on ischemic diseases, stratified by lipid levels: a drug-target, nonlinear Mendelian randomization study

Although uric acid-lowering agents such as xanthine oxidase inhibitors have potential cardioprotective effects, studies on their use in preventing cardiovascular diseases are lacking. We investigated the genetically proxied effects of reducing uric acid on ischemic cardiovascular diseases in a lipid-level-stratified population. We performed drug-target Mendelian randomization (MR) analyses using UK Biobank data to select genetic instruments within a uric acid-lowering gene, xanthine dehydrogenase (XDH), and construct genetic scores. For nonlinear MR analyses, individuals were stratified by lipid level. Outcomes included acute myocardial infarction (AMI), ischemic heart disease, cerebral infarction, transient cerebral ischemic attack, overall ischemic disease, and gout. We included 474,983 non-gout individuals with XDH-associated single-nucleotide polymorphisms. The XDH-variant-induced uric acid reduction was associated with reduced risk of gout (odds ratio [OR], 0.85; 95% confidence interval [CI], 0.78-0.93; P < 0.001), cerebral infarction (OR, 0.86; 95% CI, 0.75-0.98; P = 0.023), AMI (OR, 0.79; 95% CI, 0.66-0.94; P = 0.010) in individuals with triglycerides ≥ 188.00 mg/dL, and cerebral infarction in individuals with low-density lipoprotein cholesterol (LDL-C) ≤ 112.30 mg/dL (OR, 0.76; 95% CI, 0.61-0.96; P = 0.020) or LDL-C of 136.90-157.40 mg/dL (OR, 0.67; 95% CI, 0.49-0.92; P = 0.012). XDH-variant-induced uric acid reduction lowers the risk of gout, AMI for individuals with high triglycerides, and cerebral infarction except for individuals with high LDL-C, highlighting the potential heterogeneity in the protective effects of xanthine oxidase inhibitors for treating AMI and cerebral infarction depending on the lipid profiles.

Xanthine oxidase inhibitors treatment or discontinuation effects on mortality: evidence of xanthine oxidase inhibitors withdrawal syndrome

Objectives: This study investigates the impact of xanthine oxidase inhibitors (XOI) on mortality in patients with cardiovascular diseases. XOI withdrawal has been reported to increased mortality risk due to rapid adenosine triphosphate (ATP) deficiency. This study aims to determine whether XOI treatment reduces mortality and whether XOI withdrawal increases mortality. Methods: This is a real-world database study using the Japanese Registry of All Cardiac and Vascular Diseases (J-ROAD). We analyzed 1,648,891 hospitalized patients aged 20-90 with acute coronary syndrome or heart failure. In the first study, mortality rates were compared between patients without urate-lowering agents (n = 1,292,486) and those with XOI agents (n = 315,388, excluding 41,017 on other urate-lowering agents). In the second study, mortality rates were compared between the XOI continuous medication group (n = 226,261) and the XOI withdrawal group (n = 89,127). Results: After multiple adjustments, XOI treatment group showed significantly lower mortality compared with that without any urate-lowering agent (odds ratio (OR), 0.576, 95% confidence interval (CI), 0.567-0.587, p < .001). In the sub-analysis, the group with allopurinol (OR, 0.578; 95% CI, 0.557-0.600), febuxostat (OR, 0.610; 95% CI, 0.599-0.622), and topiroxostat (HR, 0.545; 95% CI, 0.473-0.628) showed lower OR of mortality compared with that without any urate-lowering agent. XOI withdrawal group led to significantly higher death rates compared to XOI continuous group (19.8% vs. 0.03%; p < .001). Conclusion: XOI treatment for patients with cardiovascular diseases is associated with reduced mortality. Conversely, XOI withdrawal is linked to elevated mortality risk. This emphasizes the importance of both prescribing and discontinuing XOI carefully to optimize patient outcomes.

Two cases report of febuxostat-induced acute liver injury: acute heart failure as a probable risk factor?

Drug induced liver injury, as a sub-type of hepatotoxicity, is rare but practical problem, producing challenges for clinicians. Within the recent two months, two patients with heart failure develop febuxostat-induced acute liver injury during hospital stay. To the best of our knowledge, very few cases of febuxostat-induced hepatotoxicity have been reported up to now. In this paper, two unusual cases of febuxostat-induced acute liver injury are herein described. The medical history, drug treatment, clinical symptoms, liver function tests, diagnosis and prognosis are fully given in this paper. It should be noticed that, two liver injury happen in patients of heart failure with reduced ejection fraction. Whether heart failure is a risk factor of febuxostat related liver injury, deserves further research. This paper reminds the clinicians that more attention should be paid to the acute liver injury caused by febuxostat, and liver function tests are suggested especially for patients of heart failure.

A dose-escalation study of HP501, a highly selective URAT1 inhibitor, in male Chinese patients with hyperuricemia

HP501 is a highly selective renal urate transporter 1 (URAT1) inhibitor used for treating hyperuricemia. This study aimed to evaluate the tolerability, pharmacokinetics, and pharmacodynamics of HP501 in male Chinese patients. Patients with hyperuricemia were sequentially assigned to receive oral doses of HP501 (30, 50, 60, 90, and 120 mg) as a single dose on Day 1 and as once-daily doses from Days 4 to 13. Safety, pharmacokinetic, and pharmacodynamic data were collected. Multiple oral doses of HP501 were well-tolerated in all the cohorts. The most common adverse events (≥ 10% of patients) of any grade regardless of drug relationship were gout flare (14 patients, 25.93%), diarrhea (12 patients, 22.22%), elevated ALT (8 patients, 14.81%), hypertriglyceridemia (7 patients, 12.96%), dry mouth (7 patients, 12.96%) and oral ulcer (7 patients, 12.96%). All adverse events were mild or moderate. The Cmax and exposure (AUC) of HP501 was approximately dose-proportional between 30 and 120 mg. A dose-dependent serum uric acid (UA)-lowering effect was observed in the dose range of 30 to 60 mg and the serum UA lowering effect was similar between 90 and 120 mg on day 13, indicating that the maximal serum UA lowering effect of HP501 was achieved at 90 mg in the patients with hyperuricemia. In conclusion, the tolerability, pharmacokinetics, and pharmacodynamics supported 90 mg HP501 for subsequent clinical studies of this highly selective URAT1 inhibitor.Clinical Trial registration: No. CTR20212259 ( http://www.chinadrugtrials.org.cn/ ) was registered in September 2021, and No. CTR20222257 was registered in September 2022.

Effectiveness and safety of different doses of febuxostat compared with allopurinol in the treatment of hyperuricemia: a meta-analysis of randomized controlled trials

BACKGROUND

The prevalence of hyperuricemia has increased steadily with the continuous improvement of living standards. Some studies have reported the clinical effectiveness and safety of different doses of febuxostat in comparison with allopurinol in hyperuricemia treatment, but the sample sizes of the studies have been small, and the results have been inconsistent. We designed this meta-analysis to evaluate the effectiveness and safety of different doses of febuxostat compared with allopurinol in the treatment of hyperuricemia.

METHODS

The Cochrane Library, Embase, PubMed, Web of Science and ClinicalTrials.gov databases were searched to identify randomized controlled trials (RCTs) comparing the use of febuxostat and allopurinol for the treatment of hyperuricemia. The effectiveness and safety of different doses of febuxostat and allopurinol in treating hyperuricemia were assessed using meta-analysis.

RESULTS

A total of 11 randomized controlled trials were included in the meta-analysis. The results of the meta-analysis showed that the percentage of patients achieving serum uric acid levels of 6.0 mg/dL or less was higher among patients taking febuxostat (80 mg/d) than among patients taking allopurinol (200-300 mg/d) [RR = 1.79, 95% CI (1.55, 2.08), P < 0.00001]. However, there was no statistically significant difference in the percentage of patients achieving serum uric acid levels of 6.0 mg/dL or less between febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 1.10, 95% CI (0.93, 1.31), P = 0.25]. There was also no statistically significant difference in the incidence of gout between the febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 0.97, 95% CI (0.64, 1.49), P = 0.91] or between the febuxostat (80 mg/d) and allopurinol (200-300 mg/d) [RR = 1.13, 95% CI (0.81, 1.58), P = 0.48].No significant difference in the incidence of major adverse reactions as observed between the febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 1.16; 95% CI (0.43, 3.16), P = 0.77] or between the febuxostat (80 mg/d) and allopurinol (200-300 mg/d) [RR = 1.06; 95% CI (0.79, 1.42), P = 0.70]. The incidence of adverse cardiovascular events did not differ significantly between the febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 1.30; 95% CI (0.57, 2.95), P = 0.53] or between the febuxostat (80 mg/d) and allopurinol (200-300 mg/d) [RR = 1.79; 95% CI (0.74, 4.32), P = 0.20].

CONCLUSIONS

Febuxostat (80 mg/d) was associated with a higher percentage of patients achieving serum uric acid levels of 6.0 mg/dL or less than allopurinol (200-300 mg/d), however, febuxostat (80 mg/d) did not exhibit better efficacy in reducing the incidence of gout. More attention should be devoted to the adverse reactions caused by an increase in febuxostat doses.

Serum uric acid: a futile bystander in endothelial function?

PURPOSE

This study aims to investigate the relationship between serum uric acid levels and endothelial function, oxidative stress, and hemodynamic parameters, and to determine if uric acid levels provide additional insights beyond traditional factors like ageing and hypertension in volunteers with low cardiovascular risk factors. Serum uric acid is known for its antioxidant properties, but it may also contribute to cardiovascular risk.

MATERIALS AND METHODS

The study enrolled 40 male participants, divided into three groups based on age and blood pressure status. Group 1 comprised younger participants, group 2 included older individuals without hypertension, and group 3 consisted of older patients with hypertension. The study assessed endothelial function using laser Doppler imaging and measured acetylcholine- and sodium nitroprusside-induced hyperaemia. The heat microcirculatory response was also examined in the presence of L-NAME, an inhibitor of NOS synthase. The study evaluated oxidative stress and arterial stiffness by measuring allantoin, angiotensin II, Homocitrulline/Lysine, and Chloro-Tyrosine/Tyrosine ratios, as well as by performing non-invasive measurements of aortic augmentation indexes and carotid-femoral pulse wave velocity.

RESULTS

The study found that uric acid levels did not differ significantly among the three groups. Augmentation indexes increased with ageing, but hypertension did not have an additional effect. Blood pressure and carotid-femoral pulse wave velocity differed among the groups, with the lowest values among younger participants and the highest values among older individuals with hypertension. Allantoin and angiotensin II levels did not differ among the groups. However, Homocitrulline/Lysine and Chloro-Tyrosine/Tyrosine ratios were significantly lower in young subjects. Correlation and multivariable analysis showed that uric acid had no effect on any of the studied parameters. Despite a strong association between ageing and systolic blood pressure with impaired endothelial function, oxidative stress, and arterial stiffness, only ageing retained a significant effect in the multivariable analysis.

CONCLUSION

In healthy or hypertensive adults with normal renal function, serum uric acid appears to be a futile bystander in endothelial function, oxidative stress, and arterial stiffness, in contrast to ageing, which reduces NO bioavailability. This study suggests that traditional factors such as ageing and hypertension should be the focus of clinical assessment and management of cardiovascular risk, rather than uric acid levels.

Emerging Urate-Lowering Drugs and Pharmacologic Treatment Strategies for Gout: A Narrative Review

Hyperuricemia with consequent monosodium urate crystal deposition leads to gout, characterized by painful, incapacitating inflammatory arthritis flares that are also associated with increased cardiovascular event and related mortality risk. This narrative review focuses on emerging pharmacologic urate-lowering treatment (ULT) and management strategies in gout. Undertreated, gout can progress to palpable tophi and joint damage. In oral ULT clinical trials, target serum urate of < 6.0 mg/dL can be achieved in ~ 80-90% of subjects, with flare burden reduction by 1-2 years. However, real-world ULT results are far less successful, due to both singular patient nonadherence and prescriber undertreatment, particularly in primary care, where most patients are managed. Multiple dose titrations commonly needed to optimize first-line allopurinol ULT monotherapy, and substantial potential toxicities and other limitations of approved, marketed oral monotherapy ULT drugs, promote hyperuricemia undertreatment. Common gout comorbidities with associated increased mortality (e.g., moderate-severe chronic kidney disease [CKD], type 2 diabetes, hypertension, atherosclerosis, heart failure) heighten ULT treatment complexity and emphasize unmet needs for better and more rapid clinically significant outcomes, including attenuated gout flare burden. The gout drug armamentarium will be expanded by integrating sodium-glucose cotransporter-2 (SGLT2) inhibitors with uricosuric and anti-inflammatory properties as well as clinically indicated antidiabetic, nephroprotective, and/or cardioprotective effects. The broad ULT developmental pipeline is loaded with multiple uricosurics that selectively target uric acid transporter 1 (URAT1). Evolving ULT approaches include administering selected gut anaerobic purine degrading bacteria (PDB), modulating intestinal urate transport, and employing liver-targeted xanthine oxidoreductase mRNA knockdown. Last, emerging measures to decrease the immunogenicity of systemically administered recombinant uricases should simplify treatment regimens and further improve outcomes in managing the most severe gout phenotypes.

Exploring the Multifaceted Nexus of Uric Acid and Health: A Review of Recent Studies on Diverse Diseases

The prevalence of patients with hyperuricemia or gout is increasing worldwide. Hyperuricemia and gout are primarily attributed to genetic factors, along with lifestyle factors like consuming a purine-rich diet, alcohol and/or fructose intake, and physical activity. While numerous studies have reported various comorbidities linked to hyperuricemia or gout, the range of these associations is extensive. This review article focuses on the relationship between uric acid and thirteen specific domains: transporters, genetic factors, diet, lifestyle, gout, diabetes mellitus, metabolic syndrome, atherosclerosis, hypertension, kidney diseases, cardiovascular diseases, neurological diseases, and malignancies. The present article provides a comprehensive review of recent developments in these areas, compiled by experts from the Young Committee of the Japanese Society of Gout and Uric and Nucleic Acids. The consolidated summary serves to enhance the global comprehension of uric acid-related matters.

Gout Treatment and Clinical Considerations: The Role of Pegloticase, Colchicine, and Febuxostat

Gout treatment has evolved rapidly in recent decades, and various drugs have been designed for acute and chronic management. Three medications used to treat gout include pegloticase, colchicine, and febuxostat. When prescribing these drugs, important factors to consider include pharmacokinetics, pharmacodynamics, population specifics, benefits, and contraindications. Pharmacokinetic considerations of each drug include absorption, distribution, metabolism, and elimination factors. Pharmacodynamics factors are assessed by their potential for toxicity and effects on serum uric acid levels. Additionally, the drug's targeted population must be considered to avoid unwanted complications in certain pre-existing conditions such as cardiovascular disease or glucose-6-dehydrogenase (G6PD) deficiency. In this paper, we aim to provide insight into the gout medications, pegloticase, colchicine, and febuxostat. This review will include their pharmacokinetics, pharmacodynamics, population specifics, benefits, and contraindications.

The Impact of Label Changes (Boxed Warning) on Real-World Febuxostat Utilization in Patients with Gout: A Cross-Sectional Drug Utilization Study

INTRODUCTION

This drug utilization study evaluated the impact of 2019 label changes on real-world febuxostat utilization among patients with gout. We describe the numbers and proportions of patients initiating febuxostat as new users (allopurinol-naïve) or prevalent new users (prior allopurinol use) and data on febuxostat users with established cardiovascular disease (CVD) morbidities before, during, and after the 2019 label changes.

METHODS

This descriptive, non-interventional, cross-sectional study used data from two large administrative claims databases in the United States, the IQVIA PharMetrics Plus database and the Optum Research Database (ORD). The study population included patients with gout initiating febuxostat on or after June 1, 2016. Data were collected on febuxostat and allopurinol use, established CVD morbidities, comorbidities of interest, concomitant medications, and patient demographics.

RESULTS

In both databases, the total number of febuxostat users and proportion of patients who initiated febuxostat as new users both decreased during the study period. Of 13,848 patients in the PharMetrics Plus cohort, 42.7% were new users of febuxostat and 57.3% were prevalent new users. In the ORD cohort, 40.5% of the 10,198 patients were new users and 59.5% were prevalent new users. The most common established CVD morbidities in the 12 months prior to initiation of febuxostat were diabetes mellitus, ischemic heart disease, and heart failure/cardiomyopathy.

CONCLUSIONS

Although the benefit-risk profile for febuxostat is considered favorable for the treatment of hyperuricemia in certain patients with gout, real-world febuxostat utilization decreased during the study period, presumably in response to the label change.

Gout therapeutics and drug delivery

Gout is a common inflammatory arthritis caused by persistently elevated uric acid levels. With the improvement of people's living standards, the consumption of processed food and the widespread use of drugs that induce elevated uric acid, gout rates are increasing, seriously affecting the human quality of life, and becoming a burden to health systems worldwide. Since the pathological mechanism of gout has been elucidated, there are relatively effective drug treatments in clinical practice. However, due to (bio)pharmaceutical shortcomings of these drugs, such as poor chemical stability and limited ability to target the pathophysiological pathways, traditional drug treatment strategies show low efficacy and safety. In this scenario, drug delivery systems (DDS) design that overcome these drawbacks is urgently called for. In this review, we initially describe the pathological features, the therapeutic targets, and the drugs currently in clinical use and under investigation to treat gout. We also comprehensively summarize recent research efforts utilizing lipid, polymeric and inorganic carriers to develop advanced DDS for improved gout management and therapy.

Mechanisms and rationale for uricase use in patients with gout

Xanthine oxidase inhibitors such as allopurinol and febuxostat have been the mainstay urate-lowering therapy (ULT) for treating hyperuricaemia in patients with gout. However, not all patients receiving oral ULT achieve the target serum urate level, in part because some patients cannot tolerate, or have actual or misconceived contraindications to, their use, mainly due to comorbidities. ULT dosage is also limited by formularies and clinical inertia. This failure to sufficiently lower serum urate levels can lead to difficult-to-treat or uncontrolled gout, usually due to poorly managed and/or under-treated gout. In species other than humans, uricase (urate oxidase) converts urate to allantoin, which is more soluble in urine than uric acid. Exogenic uricases are an exciting therapeutic option for patients with gout. They can be viewed as enzyme replacement therapy. Uricases are being used to treat uncontrolled gout, and can achieve rapid reduction of hyperuricaemia, dramatic resolution of tophi, decreased chronic joint pain and improved quality of life. Availability, cost and uricase immunogenicity have limited their use. Uricases could become a leading choice in severe and difficult-to-treat gout as induction and/or debulking therapy (that is, for lowering of the urate pool) to be followed by chronic oral ULT. This Review summarizes the evidence regarding available uricases and those in the pipeline, their debulking effect and their outcomes related to gout and beyond.

Cardiovascular Safety Evaluation of Febuxostat and Allopurinol: Findings from the FDA Adverse Event Reporting System

BACKGROUND

Febuxostat and allopurinol are the most commonly used uric acid-lowering medications, and their safety is of great concern, especially the cardiovascular adverse reactions associated with febuxostat. We propose to study the cardiovascular toxicity of febuxostat and allopurinol using the FDA Adverse Event Reporting System (FAERS) database.

METHODS

A total of 64 quarters of FAERS data were downloaded from 2004 to 2019. Febuxostat- and allopurinol-related cardiovascular adverse events were extracted after data cleaning. Signal detection was conducted by reporting odds ratio (ROR) and proportional reporting ratio (PRR).

RESULTS

There were 2939 and 25,219 reports of febuxostat- and allopurinol-related cardiovascular adverse events (CVAEs), respectively. The most frequent CVAEs with febuxostat and allopurinol were edema peripheral (14.38%) and peripheral swelling (8.76%), respectively. In elderly gout patients, febuxostat is associated with an increased risk of heart failure, ischemic heart disease, hypertension, and cardiomyopathy. Febuxostat in combination with acetic acid derivatives nonsteroidal anti-inflammatory drug (NSAIDS) also increases the risk of cardiovascular adverse events.

CONCLUSIONS

Compared with allopurinol, febuxostat may increase cardiovascular toxicity in patients with gout.

Allopurinol for Secondary Prevention in Patients with Cardiovascular Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The effects of allopurinol in patients with cardiovascular disease are not well defined; therefore, the latest evidence is summarized in this study.

METHODS

PubMed, Embase, Cochrane Library, and ClinicalTrials.gov databases were searched for randomized controlled trials (RCTs) of allopurinol in patients with cardiovascular disease published up to 11 February 2023. The primary outcome was cardiovascular death.

RESULTS

We combined the results of 21 RCTs that included 22,806 patients. Compared to placebo/usual care, allopurinol treatment was not associated with a significant reduction in cardiovascular death (RR 0.60; 95% CI 0.33-1.11) or all-cause death (RR 0.90; 95% CI 0.72-1.12). However, evidence from earlier trials and studies with small sample sizes indicated that allopurinol might confer a protective effect in decreasing cardiovascular death (RR 0.34; 95% CI 0.15-0.76) across patients undergoing coronary artery bypass grafting (CABG) or having acute coronary syndrome (ACS). In comparisons between allopurinol and febuxostat, we observed no difference in cardiovascular death (RR 0.92; 95% CI 0.69-1.24) or all-cause death (RR 1.02; 95% CI 0.75-1.38).

CONCLUSION

Allopurinol could not reduce cardiovascular (CV) death or major adverse CV outcomes significantly in patients with existing cardiovascular diseases. Given the limitations of the original studies, the potential advantages of allopurinol observed in patients undergoing CABG or presenting with ACS necessitate further confirmation through subsequent RCTs. In the comparisons between allopurinol and febuxostat, our analysis failed to uncover any marked superiority of allopurinol in reducing the risk of adverse cardiovascular incidents.

Management of Patients with Gout and Kidney Disease: A Review of Available Therapies and Common Missteps

Gout, a common form of inflammatory arthritis, is characterized by deposition of monosodium urate crystals in articular and periarticular tissues. Repeated flares of gout cause joint damage as well as significant health care utilization and decreased quality of life. Patients with CKD have a higher prevalence of gout. Treating Patients with CKD and gout is challenging because of the lack of quality data to guide management in this specific population. This often leads to suboptimal treatment of patients with gout and impaired renal function because concerns regarding the efficacy and safety of available gout therapies in this population often result in significant interphysician variability in treatment regimens and dosages. Acute gout flares are treated with various agents, including nonsteroidal anti-inflammatory drugs, colchicine, glucocorticoids, and-more recently-IL-1 inhibitors. These medications can also be used as prophylaxis if urate-lowering therapy (ULT) is initiated. While these drugs can be used in patients with gout and CKD, there are often factors that complicate treatment, such as the numerous medication interactions involving colchicine and the effect of glucocorticoids on common comorbidities, such as diabetes and hypertension. ULT is recommended to treat recurrent flares, tophaceous deposits, and patients with moderate-to-severe CKD with a serum urate goal of <6 mg/dl recommended to prevent flares. While many misconceptions exist around the risks of using urate-lowering agents in patients with CKD, there is some evidence that these medications can be used safely in Patients with renal impairment. Additional questions exist as to whether gout treatment is indicated for Patients on RRT. Furthermore, there are conflicting data on whether ULT can affect renal function and cardiovascular disease in patients. All of these factors contribute to the unique challenges physicians face when treating patients with gout and CKD.

Simiao San alleviates hyperuricemia and kidney inflammation by inhibiting NLRP3 inflammasome and JAK2/STAT3 signaling in hyperuricemia mice

ETHNOPHARMACOLOGICAL RELEVANCE

Simiao San (SmS), a famous traditional Chinese formula, is clinically used to treat patients with hyperuricemia (HUA). However, its mechanism of action on lowering uric acid (UA) and inhibiting inflammation still deserves further investigation.

AIM OF THE STUDY

To examine the effect and its possible underlying mechanism of SmS on UA metabolism and kidney injury in HUA mouse.

MATERIALS AND METHODS

The HUA mouse model was constructed with the combined administration of both potassium oxalate and hypoxanthine. The effects of SmS on UA, xanthine oxidase (XOD), creatinine (CRE), blood urea nitrogen (BUN), interleukin-10 (IL-10), interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were determined by ELISA or biochemical assays. Hematoxylin and eosin (H&E) was used to observe pathological alterations in the kidneys of HUA mice. The expression levels of organic anion transporter 1 (OAT1), recombinant urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), nucleotide binding domain and leucine rich repeat pyrin domain containing 3 (NLRP3), Cleaved-Caspase 1, apoptosis-associated speck like protein (ASC), nuclear factor kappa-B (NF-κB), IL-6, janus kinase 2 (JAK2), phosphor (P)-JAK2, signal transducers and activators of transcription 3 (STAT3), P-STAT3, suppressor of cytokine signaling 3 (SOCS3) were examined by Western blot and/or immunohistochemical (IHC) staining. The major ingredients in SmS were identified by a HPLC-MS assay.

RESULTS

HUA mouse exhibited an elevation in serum levels of UA, BUN, CRE, XOD, and the ratio of urinary albumin to creatinine (UACR), and a decline in urine levels of UA and CRE. In addition, HUA induces pro-inflammatory microenvironment in mouse, including an increase in serum levels of IL-1β, IL-6, and TNF-α, and renal expressions of URAT1, GULT9, NLRP3, ASC, Cleaved-Caspase1, P-JAK2/JAK2, P-STAT3/STAT3, and SOCS3, and a decrease in serum IL-10 level and renal OAT1 expression as well as a disorganization of kidney pathological microstructure. In contrast, SmS intervention reversed these alterations in HUA mouse.

CONCLUSION

SmS could alleviate hyperuricemia and renal inflammation in HUA mouse. The action mechanisms behind these alterations may be associated with a limitation of the NLRP3 inflammasome and JAK2/STAT3 signaling pathways.

Comparative Effectiveness of Sodium-Glucose Cotransporter-2 Inhibitors for Recurrent Gout Flares and Gout-Primary Emergency Department Visits and Hospitalizations : A General Population Cohort Study

BACKGROUND

Sodium-glucose cotransporter-2 inhibitors (SGLT2is) decrease serum urate levels, but whether this translates into prevention of recurrent flares among patients with gout and gout-primary emergency department (ED) visits or hospitalizations is unknown.

OBJECTIVE

To compare gout flares and cardiovascular events among patients with gout initiating SGLT2is versus dipeptidyl peptidase 4 inhibitors (DPP-4is), another second-line glucose-lowering agent not associated with serum urate levels or cardiovascular risk.

DESIGN

Propensity score-matched, new-user cohort study.

SETTING

General population database from 1 January 2014 to 30 June 2022.

PARTICIPANTS

Patients with gout and type 2 diabetes.

MEASUREMENTS

The primary outcome was recurrent gout flare counts ascertained by ED, hospitalization, outpatient, and medication dispensing records. Secondary outcomes included myocardial infarction and stroke; genital infection (positive control) and osteoarthritis encounter (negative control) were also assessed. Poisson and Cox proportional hazards regressions were used with 1:1 propensity score matching (primary analysis) and overlap weighting (sensitivity analysis).

RESULTS

After propensity score matching, the flare rate was lower among SGLT2i initiators than DPP-4i initiators (52.4 and 79.7 events per 1000 person-years, respectively), with a rate ratio (RR) of 0.66 (95% CI, 0.57 to 0.75) and a rate difference (RD) of -27.4 (CI, -36.0 to -18.7) per 1000 person-years. The corresponding RR and RD for gout-primary ED visits and hospitalizations were 0.52 (CI, 0.32 to 0.84) and -3.4 (CI, -5.8 to -0.9) per 1000 person-years, respectively. The corresponding hazard ratio (HR) and RD for myocardial infarction were 0.69 (CI, 0.54 to 0.88) and -7.6 (CI, -12.4 to -2.8) per 1000 person-years; the HR for stroke was 0.81 (CI, 0.62 to 1.05). Those who initiated SGLT2is showed higher risk for genital infection (HR, 2.15 [CI, 1.39 to 3.30]) and no altered risk for osteoarthritis encounter (HR, 1.07 [CI, 0.95 to 1.20]). Results were similar when propensity score overlap weighting was applied.

LIMITATION

Participants had concurrent type 2 diabetes.

CONCLUSION

Among patients with gout, SGLT2is may reduce recurrent flares and gout-primary ED visits and hospitalizations and may provide cardiovascular benefits.

PRIMARY FUNDING SOURCE

National Institute of Arthritis and Musculoskeletal and Skin Diseases.

Update in uric acid, hypertension, and cardiovascular diseases

A direct relationship between serum uric acid levels and hypertension, cardiovascular, renal and metabolic diseases has been reported in many basic and epidemiological studies. Among these, high blood pression is one of the most common features associated with hyperuricemia. In this regard, several small-scale interventional studies have demonstrated a significant reduction in blood pressure in hypertensive or prehypertensive patients on uric acid-lowering drugs. These observation or intervention studies have led to affirm that there is a causal relationship between uric acid and hypertension. While the clinical association between uric acid and high blood pressure is notable, no clear conclusion has yet been reached as to whether lowering uric acid is beneficial to prevent cardiovascular and renal metabolic diseases. Recently, several prospective randomized controlled intervention trials using allopurinol and other uric acid-lowering drugs have been reported, and the results from these trials were almost negative, suggesting that the correlation between hyperuricemia and cardiovascular disease has no causality. However, it is important to note that in some of these recent studies there were high dropout rates and an important fraction of participants were not hyperuricemic. Therefore, we should carry caution in interpreting the results of these studies. This review article presents the results of recent clinical trials using uric acid-lowering drugs, focusing on hypertension and cardiovascular and renal metabolic diseases, and discusses the future of uric acid therapy.

Comparative Safety of Gout Treatment Strategies on Cardiovascular Outcomes Using Observational Data: Clone-censor-weight Target Trial Emulation Approach

BACKGROUND

We sought to examine the cardiovascular safety of intensive treat-to-target serum urate strategies for gout using Medicare claims data linked to electronic health record laboratory data.

METHODS

We selected patients with gout who initiated urate-lowering therapy. We emulated a hypothetical trial comparing the rate of major adverse cardiovascular events (nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death) among seven different strategies over 24 months. Three aspects were considered in defining increasingly intensive strategies: (1) continuation of urate-lowering therapy, (2) serum urate monitoring, and (3) modification of urate-lowering therapy when serum urate >6 mg/dl. We applied the "clone-censor-weight" method to account for baseline and time-varying confounding.

RESULTS

We identified 4402 patients with gout who initiated urate-lowering therapy (mean age 77; male 60%). During a total of 6611 person-years (PY) of follow-up under usual care, the rate of major cardiovascular events (first and recurrent) was 4.5/100 PY (95% CI = 4.0, 5.1). The rate ratios (RRs) suggested reductions (RR point estimates 0.88-0.84) compared with usual care. All 95% CIs were imprecise, but their upper bounds excluded substantial increase in RRs. RRs were closer to 1.0 for the analysis focusing on the first major adverse cardiovascular event during follow-up and on comparison to the strategy requiring continuation of urate-lowering therapy (but not necessarily titration).

CONCLUSIONS

Our treatment strategy trial emulation did not find increased risk of major adverse cardiovascular events with intensive urate-lowering strategies. Results may provide reassurance of the cardiovascular safety of intensive treat-to-target serum urate strategies recommended by rheumatology societies.

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

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

Asymptomatic hyperuricaemia in chronic kidney disease: mechanisms and clinical implications

Asymptomatic hyperuricaemia (HU) is considered a pathogenic factor in multiple disease contexts, but a causative role is only proven for the crystalline form of uric acid in gouty arthritis and urate nephropathy. Epidemiological studies document a robust association of HU with hypertension, cardiovascular disease (CVD) and CKD progression, but CKD-related impaired uric acid (UA) clearance and the use of diuretics that further impair UA clearance likely accounts for these associations. Interpreting the available trial evidence is further complicated by referring to xanthine oxidase inhibitors as urate-lowering treatment, although these drugs inhibit other substrates, so attributing their effects only to HU is problematic. In this review we provide new mechanistic insights into the biological effects of soluble and crystalline UA and discuss clinical evidence on the role of asymptomatic HU in CKD, CVD and sterile inflammation. We identify research areas with gaps in experimental and clinical evidence, specifically on infectious complications that represent the second common cause of death in CKD patients, referred to as secondary immunodeficiency related to kidney disease. In addition, we address potential therapeutic approaches on how and when to treat asymptomatic HU in patients with kidney disease and where further interventional studies are required.

Gout and hyperuricaemia: modifiable cardiovascular risk factors?

Gout and hyperuricaemia are two clinical situations associated with an elevated risk of developing cardiovascular (heart failure, myocardial infarction, stroke) and metabolic and renal complications. One reason is probably related to the fact that the prevalence of hyperuricaemia and gout is high in clinical situations, which themselves involve a high cardiovascular risk, such as hypertension, diabetes, chronic kidney disease or obesity. However, recent studies suggest that hyperuricaemia may promote cardiovascular complications independently of other cardiovascular risk factors, by inducing chronic inflammation, oxidative stress, and endothelial dysfunction. The questions that arise today concern primarily the treatment of asymptomatic hyperuricaemia. Should it be treated to decrease the patients' cardiovascular risk and if so, starting from which level and towards which target? There are now several pieces of evidence indicating that this might be useful, but data from large studies are not unanimous. This review will discuss this issue as well as new well-tolerated treatments, such as febuxostat or SGLT2 inhibitors, which lower uric acid levels, prevent gout and lower the risk of cardio-renal events.