Urate-Lowering Drugs and Prevention of Cardiovascular Disease

Effects of WN1703 on Cardiovascular Function in Chronic Hyperuricemia Rats and Myocardial Injury Mechanism Exploration in H9C2 Cells

Hyperuricemia, a prevalent condition, is typically preceded by disturbances in purine metabolism and is frequently associated with hyperlipidemia and other dysfunctions of metabolism. WN1703 demonstrated an inhibitory activity against xanthine oxidoreductase (XOR) that was comparable to febuxostat in our prior investigation. In this study, we assessed the cardiovascular safety of WN1703 in a chronic hyperuricemia rat model induced by potassium oxonate in combination with hypoxanthine. We investigated the changes in cardiovascular biomarkers in chronic hyperuricemia rats treated with febuxostat and WN1703, including creatine kinase (CK), CK-MB, B type natriuretic peptide (BNP), Corin protein (CRN), Neprilysin (NEP), myeloperoxidase (MPO), 8-hydroxy-2-deoxyguanosine (8-OHdG), tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), and interleukin-8 (IL-8). Additionally, we validated the potential mechanism of cardiac injury induced by WN1703 in H9C2 cells, guided by cardiotoxicity predictions from the cardioToxCSM database and network pharmacology. We observed that excessively rapid urate-lowering, oxidative stress, and inflammation could disrupt myocardial functional homeostasis and increase the risk of cardiovascular injury in hyperuricemia rats, and WN1703 treatment effectively reduced the levels oxidative stress marker 8-OHdG and inflammatory factor TNF-α. Despite the absence of organic damage to the heart with prolonged treatment of febuxostat and WN1703, potential hazard of cardiovascular injury could be associated with the modulation of the TGFβ and RHO/ROCK signaling pathways by febuxostat and WN1703. This could offer new insights into the mechanisms underlying the adverse effects caused by XOR inhibitors.

Asymptomatic hyperuricemia: to treat or not a threat? A clinical and evidence-based approach to the management of hyperuricemia in the context of cardiovascular diseases

Asymptomatic hyperuricemia is defined by serum uric acid levels above 6.2 mg/dl in women and 7 mg/dl in men. In the presence of monosodium urate crystal formation and articular inflammation, hyperuricemia may become symptomatic (namely nephrolithiasis and gout). Uric acid results from purine catabolism and is at the centre of a complex metabolic interplay that involves oxidative stress, inflammation, renin-angiotensin-aldosterone system (RAAS) activation and insulin resistance. Uric acid levels present a continuous relation with conditions like hypertension and chronic kidney disease (CKD) and are reported to have an impact on risk of cardiovascular events. However, whether elevated uric acid is a causal agent and thus a possible therapeutic target is still uncertain and matter of further investigation. Treating symptomatic hyperuricemia involves lowering uric acid drugs and controlling inflammation. Urate-lowering agents are well tolerated but show minimal impact on cardiovascular events in patients with gout. Use of direct-acting urate-lowering agents in asymptomatic hyperuricemia associated with cardiovascular diseases does not warrant a clear benefit, whereas addressing cardiovascular issues with guideline-recommended therapies lowers uric acid and reduces the occurrence of cardiovascular events. Regular assessment of uric acid and clinical symptoms is advised before starting and renewing a urate-lowering treatment.

Tophi and carotid atherosclerosis in gout patients: Role of insulin resistance

BACKGROUND AND AIM

Gout and cardiovascular disease are closely related, but the mechanism linking them is still unknown. Gout may affect the insulin signaling pathway inducing insulin resistance (IR). The study aims to evaluate the association between tophi and carotid atherosclerosis, considering the potential role of IR.

METHODS AND RESULTS

A total of 595 patients with gout aged 18 to 80 were enrolled in this study. Carotid intima-media thickness, plaques and tophi were evaluated by B-mode ultrasonography. IR was assessed by the HOMA index (hepatic IR) and Gutt index (peripheral IR). Multivariable logistic regression and interaction analysis were used to examine the association between tophi and IR and its impact on carotid atherosclerosis. Among these participants, the average age was 55.4 (±12.54) years, and 94.6 % were male. Tophi were associated with increased odds of carotid atherosclerosis and burden after adjustment for confounders (P < 0.05). Tophi and IR synergically interacted for inducing carotid atherosclerosis. The interaction between peripheral IR with tophi was more pronounced than hepatic IR with tophi.

CONCLUSIONS

Tophi were independently associated with carotid atherosclerosis risk. IR mediated a significant amount of the effect of tophi on the development of carotid atherosclerosis. Peripheral IR probably plays a more important role than hepatic IR does.

Curcumin Derivatives Linked to a Reduction of Oxidative Stress in Mental Dysfunctions and Inflammatory Disorders

Stress is a critical factor in the etiology of inflammation and neurodegeneration. The risk factor for the majority of psychiatric disorders is oxidative stress-induced depression. Mitochondrial damage and oxidative stress are associated with the development of neurodegenerative disorders. During aging, the brain and associated regions become more susceptible due to oxidative stress. The leading cause of oxidative stress is the continuous generation of ROS (reactive oxygen species) and RNS (Reactive nitrogen species) endogenously or exogenously. In this review, discussion on a potent antioxidant natural constituent "curcumin" has been made to alleviate many pathological and neurological disorders. A focused compilation of vast and informative research on the potential of curcumin as a magical moiety used therapeutically has been done in search of its role in controlling the neurological and similar disorders induced by oxidative stress.

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.

Celebrating Versatility: Febuxostat's Multifaceted Therapeutic Application

Febuxostat, initially developed as a xanthine oxidase inhibitor to address hyperuricemia in gout patients, has evolved into a versatile therapeutic agent with multifaceted applications. This review provides a comprehensive overview of febuxostat's mechanism of action, its effectiveness in gout management, its cardiovascular safety profile, renal and hepatic effects, musculoskeletal applications, safety considerations, and emerging research prospects. Febuxostat's primary mechanism involves selective inhibition of xanthine oxidase, resulting in reduced uric acid production. Its pharmacokinetics require personalized dosing strategies based on individual characteristics. In gout management, febuxostat offers a compelling alternative, effectively lowering uric acid levels, relieving symptoms, and supporting long-term control, especially for patients intolerant to allopurinol. Recent studies have demonstrated its cardiovascular safety, and it exhibits minimal hepatotoxicity, making it suitable for those with liver comorbidities. Febuxostat's potential nephroprotective effects and kidney stone prevention properties are noteworthy, particularly for gout patients with renal concerns. Beyond gout, its anti-inflammatory properties hint at applications in musculoskeletal conditions and a broader spectrum of clinical contexts, including metabolic syndrome. Emerging research explores febuxostat's roles in cardiovascular health, neurological disorders, rheumatoid arthritis, and cancer therapy, driven by its anti-inflammatory and antioxidative properties. Future directions include personalized medicine, combination therapies, mechanistic insights, and ongoing long-term safety monitoring, collectively illuminating the promising landscape of febuxostat's multifaceted therapeutic potential.

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.

Uric Acid and Hypertension: a Review of Evidence and Future Perspectives for the Management of Cardiovascular Risk

Uric acid is the final product of purine metabolism, and its increased serum levels have been directly involved in the pathogenesis and natural history of hypertension. The relationship between elevated uric acid and hypertension has been proven in both animals and humans, and its relevance is already evident in childhood and adolescent population. The mechanism responsible for blood pressure increase in hyperuricemic subjects is implicating both oxidative stress and intracellular urate activity with a primary involvement of XOR (xanthine-oxidoreductase activity). An increase in the relative risk of hypertension has been confirmed by genetic data and by large meta-analyses of epidemiological data. The effects of urate-lowering treatment on blood pressure control in patients with elevated serum uric acid has been investigated in a small number of reliable studies with a large heterogeneity of patient populations and study designs. However, 2 large meta-analyses suggest a significant effect of urate-lowering treatment on blood pressure, thus confirming the significant relationship between high serum urate and blood pressure. The future research should be focused on a more appropriate identification of patients with cardiovascular hyperuricemia by considering the correct cardiovascular threshold of serum urate, the time-course of uricemia fluctuations, and the identification of reliable markers of urate overproduction that could significantly clarify the clinical and therapeutic implications of the interaction between serum uric acid and hypertension.

Hypertension and Hypercholesterolemia: Let's Make Therapy Easy and Efficient

Arterial hypertension and hypercholesterolemia increase the risk of cardiovascular morbidity and mortality. Effectively reducing both blood pressure and circulating low-density lipoprotein cholesterol may considerably reduce cardiovascular risk. As this is particularly true if the intervention starts early, it is very important to identify and treat hypertension and hypercholesterolemia as early as possible. By improving adherence, a single-pill formulation that offers a combination of different drugs could be an effective way to manage patients with multiple cardiovascular risks.

Impact of serum uric acid levels on cardiovascular events and quality of life in patients with chronic coronary syndromes: Insights from a contemporary, prospective, nationwide registry

BACKGROUND AND AIMS

Hyperuricemia is a metabolic disorder that has been associated with adverse cardiovascular (CV) events. Using the data from a nationwide, prospective registry on patients with chronic coronary syndromes (CCS), we assessed the impact of serum uric acid (SUA) levels on quality of life (QoL) and major adverse CV events (MACE), a composite of CV death and hospitalization for myocardial infarction, heart failure (HF), angina or revascularization at 1-year.

METHODS AND RESULTS

Among the 5070 consecutive CCS patients enrolled in the registry, levels of SUA were available for 2394 (47.2%). Patients with SUA levels available at baseline were grouped as low tertile (n = 860; 4.3 [3.7-4.7] mg/dL), middle tertile (n = 739; 5.6 [5.3-5.9] mg/dL) and high tertile (n = 795; 7.1 [6.7-7.9] mg/dL). At 1 year, the incidence of MACE was 3.7%, 4.1% and 6.8% for low, middle and high tertiles, respectively (p = 0.005 for low vs high tertile). Patients in the high tertile of SUA had a significantly higher rate of CV mortality (1.4% vs 0.4%; p = 0.05) and hospital admission for HF (2.8% vs 1.6%; p = 0.03) compared to the low tertile. However, hyperuricemia did not result as an independent predictor of MACE at multivariable analysis [hazard ratio: 1.27; 95% confidence intervals: 0.81-2.00; p = 0.3].

CONCLUSIONS

In this contemporary, large cohort of CCS, those in the high tertile of SUA had a greater burden of CV disease and worse QoL. However, SUA did not significantly influence the higher rate of CV mortality, hospitalization for HF and MACE observed in these patients during 1-year follow-up.

Impact of serum uric acid levels on the clinical prognosis and severity of coronary artery disease in patients with acute coronary syndrome and hypertension after percutaneous coronary intervention: a prospective cohort study

OBJECTIVE

The impact of serum uric acid (sUA) levels on the clinical prognosis and severity of coronary artery disease in patients with acute coronary syndrome (ACS) and hypertension after percutaneous coronary intervention (PCI) is not fully clear. This study aimed to assess the association among sUA levels, clinical prognosis and severity of coronary artery disease in patients with ACS and hypertension after PCI.

DESIGN

In this prospective cohort study, we followed-up patients with ACS and hypertension after PCI for 1 year to explore the risk factors for 1 year total major adverse cardiovascular events (MACEs) and multivessel coronary artery disease, the dose-effect relationship among sUA levels, MACEs and severity of coronary artery disease and correlation between sUA levels and severity of coronary artery disease (Gensini score).

SETTING/PATIENTS

Several Chinese internists followed-up 422 patients who were diagnosed with ACS and hypertension after PCI in a large tertiary hospital of Qingdao during the period from 1 June 2019 to 1 December 2019.

OUTCOME MEASURES

One-year follow-up MACEs results and coronary angiography results.

RESULTS

In the coronary angiography results, multivessel coronary artery disease (28.5% vs 21.4%, p=0.006) and non-culprit lesion vascular occlusion (11.7% vs 5.3%, p=0.042) were more common in the hyperuricaemia group, and the Gensini score (26.69±13.46 vs 17.66±10.57, p<0.001) was also higher. In the results of 1-year MACEs, the incidence of all-cause mortality (3.5% vs 2.5%, p=0.037), PCI or coronary artery bypass grafting therapy due to myocardial infarction or angina pectoris (15.1% vs 7.6%, p=0.027), medication conservative therapy in hospital due to myocardial infarction or angina pectoris (12.9% vs 6.7%, p=0.041) and total MACEs (31.8% vs 16.9%, p=0.001) were higher in patients with hyperuricaemia. Univariate and multivariate logistic regression analysis models showed that hyperuricaemia was still an independent risk factor for total MACEs within 1 year (OR=2.618, 95% CI 1.656 to 4.139, p<0.001; OR=1.920, 95% CI 1.158 to 3.183, p=0.011, respectively) and multivessel coronary artery disease (OR=2.140, 95% CI 1.371 to 3.342, p=0.001; OR=1.688, 95% CI 1.051 to 2.710, p=0.030, respectively) after adjusting for confounding factors. The severity of coronary artery disease (non-culprit lesion vascular occlusion (4.7% vs 8.4% vs 9.6% vs 16.2%, p=0.041); multivessel coronary artery disease (17.9% vs 22.4% vs 29.8% vs 35.2%, p=0.022); Gensini score (16.96±10.35 vs 19.31±10.63 vs 26.12±11.48 vs 33.33±14.01, p<0.001)) and the incidence of total MACEs (13.2% vs 14.2% vs 34.6% vs 41%, p<0.001) increased significantly with the sUA levels increasing. Further, the Gensini score was positively correlated with uric acid levels (r=0.515, p<0.001).

CONCLUSIONS

Hyperuricaemia is an independent risk factor for 1-year total MACEs and multivessel coronary artery disease in patients with ACS and hypertension after PCI.

Effects of intensive urate lowering therapy with febuxostat in comparison with allopurinol on pulse wave velocity in patients with gout and increased cardiovascular risk: the FORWARD study

AIMS

Hyperuricaemia and gout are strongly related with traditional cardiovascular risk factors and vascular damage. This study aimed to assess whether febuxostat and allopurinol could differently influence carotid-femoral pulse wave velocity (cfPWV) in patients with gout and elevated serum uric acid (SUA) levels.

METHODS AND RESULTS

A multi-centre, multinational, phase IV, randomized, parallel-group, active-controlled, open label trial with blind end-points evaluation. One hundred and ninetyseven adults with gout and SUA levels ≥8 mg/dL were randomised to febuxostat or allopurinol in a 1:1 ratio for 36 weeks. The primary outcome was the comparison of the effects of febuxostat and allopurinol on changes in cfPWV. The mean cfPWV values at randomisation and week 36 were respectively 8.69 m/s and 9.00 m/s for subjects randomised to febuxostat and 9.02 m/s and 9.05 m/s for subjects randomised to allopurinol. No statistically significant changes in cfPWV by treatment assignment were observed at any time point for any of the assessed parameters. More subjects who received febuxostat had serum urate concentrations ≤6 mg/dL following treatment (78.3% vs 61.1% at week 36, p = 0.0137). Treatment-emergent adverse events were reported by 51 (52.0%) patients randomised to febuxostat and 63 (62.5%) patients randomised to allopurinol. The majority of events were mild in both treatment groups and included gout flares and arthralgia.

CONCLUSIONS

In patients with gout and elevated SUA levels the arterial stiffness remained stable both with febuxostat and allopurinol. Febuxostat was more effective and faster than allopurinol in achieving the SUA target. Both treatments were safe and well tolerated.

Uric acid predicts long-term cardiovascular risk in type 2 diabetes but does not mediate the benefits of fenofibrate: The FIELD study

AIM

To explore the relationship between baseline uric acid (UA) levels and long-term cardiovascular events in adults with type 2 diabetes (T2D) and to determine whether the cardioprotective effects of fenofibrate are partly mediated through its UA-lowering effects.

METHODS

Data from the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial were utilized, comprising 9795 adults with T2D randomly allocated to treatment with fenofibrate or matching placebo. Plasma UA was measured before and after a 6-week, active fenofibrate run-in phase in all participants. Cox proportional hazards models were used to explore the relationships between baseline UA, pre-to-post run-in reductions in UA and long-term cardiovascular outcomes.

RESULTS

Mean baseline plasma UA was 0.33 mmol/L (SD 0.08). Baseline UA was a significant predictor of long-term cardiovascular events, with every 0.1 mmol/L higher UA conferring a 21% increase in event rate (HR 1.21, 95% CI 1.13-1.29, P < .001). This remained significant after adjustment for treatment allocation, cardiovascular risk factors and renal function. The extent of UA reduction during fenofibrate run-in was also a significant predictor of long-term cardiovascular events, with every 0.1 mmol/L greater reduction conferring a 14% lower long-term risk (HR 0.86, 95% CI 0.76-0.97, P = .015). This effect was not modified by treatment allocation (P_interaction = .77).

CONCLUSIONS

UA is a strong independent predictor of long-term cardiovascular risk in adults with T2D. Although greater reduction in UA on fenofibrate is predictive of lower cardiovascular risk, this does not appear to mediate the cardioprotective effects of fenofibrate.

The Association of Febuxostat Compared With Allopurinol on Blood Pressure and Major Adverse Cardiac Events Among Adult Patients With Hyperuricemia: A Meta-analysis

Increased uric acid levels have been known to be associated with different cardiovascular and renal diseases. Over the past few years, several studies have examined the role of urate-lowering therapy (ULT) in hypertension and major adverse cardiac events (MACE) and suggest a potential role of elevated serum uric acid as an independent cardiovascular risk factor. This meta-analysis was done to determine the association of 2 ULTs commonly used in clinical practice (febuxostat vs. allopurinol) on hypertension and MACE and resolve the conflicting results of the outcomes of earlier studies. Randomized controlled trials comparing febuxostat versus allopurinol published with outcomes on blood pressure, all-cause mortality, myocardial infarction (MI), and stroke were searched through PubMed, Google Scholar, and Cochrane database. A total of 10 studies were subsequently included in the meta-analysis. Pooled analysis of the mean differences (MD) were done for the outcomes on blood pressure (systolic and diastolic) and risk ratios (RRs) for the outcomes on MACE with corresponding 95% confidence intervals (CIs). Pooled analysis of studies on hyperuricemic patients showed that febuxostat 40 mg has no significant difference compared with allopurinol 100/300 mg with respect to diastolic (MD, -0.56 with 95% CI of -4.28 to 3.15) and systolic blood pressure (MD, 0.30 with 95% CI of -3.33 to 3.93). No significant differences were also noted on all-cause mortality (RR, 1.18 with 95% CI of 0.99-1.41), MI (RR, 0.92 with 95% CI of 0.72-1.18), and stroke (RR, 1.05 with 95% CI of 0.77-1.43). The results of this meta-analysis showed that the 2 ULTs (febuxostat vs. allopurinol) have no significant association with respect to blood pressure among adult patients with hyperuricemia. No significant association was also noted of either ULT with all-cause mortality, MI, and stroke.

Serum uric acid, predicts heart failure in a large Italian cohort: search for a cut-off value the URic acid Right for heArt Health study

OBJECTIVE

To assess the prognostic cut-off values of serum uric acid (SUA) in predicting fatal and morbid heart failure in a large Italian cohort in the frame of the Working Group on Uric Acid and Cardiovascular Risk of the Italian Society of Hypertension.

METHODS

The URic acid Right for heArt Health (URRAH) study is a nationwide, multicentre, cohort study involving data on individuals aged 18-95 years, recruited on a community basis from all regions of Italy under the patronage of the Italian Society of Hypertension with a mean follow-up period of 128 ± 65 months. Incident heart failure was defined on the basis of International Classification of Diseases Tenth Revision codes and double-checked with general practitioners and hospital files. Multivariate Cox regression models having fatal and morbid heart failure as dependent variables, adjusted for sex, age, SBP, diabetes, estimated glomerular filtration rate, smoking habit, ethanol intake, BMI, haematocrit, LDL cholesterol, previous diagnosis of heart failure and use of diuretics as possible confounders, were used to search for an association between SUA as a continuous variable and heart failure. By means of receiver operating characteristic curves, two prognostic cut-off values (one for all heart failure and one for fatal heart failure) were identified as able to discriminate between individuals doomed to develop the event. These cut-off values were used as independent predictors to divide individuals according to prognostic cut-off values in a multivariate Cox models, adjusted for confounders.

RESULTS

A total of 21 386 individuals were included in the analysis. In Cox analyses, SUA as a continuous variable was a significant predictor of all [hazard ratio 1.29 (1.23-1.359), P < 0.0001] and fatal [hazard ratio 1.268 (1.121-1.35), P < 0.0001] incident heart failure. Cut-off values of SUA able to discriminate all and fatal heart failure status were identified by mean of receiver operating characteristic curves in the whole database: SUA more than 5.34 mg/dl (confidence interval 4.37-5.6, sensitivity 52.32, specificity 63.96, P < 0.0001) was the univariate prognostic cut-off value for all heart failure, whereas SUA more than 4.89 mg/dl (confidence interval 4.78-5.78, sensitivity 68.29, specificity 49.11, P < 0.0001) for fatal heart failure. The cut-off for all heart failure and the cut-off value for fatal heart failure were accepted as independent predictors in the Cox analysis models, the hazard ratios being 1.645 (1.284-2.109, P < 0.0001) for all heart failure and 1.645 (1.284-2.109, P < 0.0001) for fatal heart failure, respectively.

CONCLUSION

The results of the current study confirm that SUA is an independent risk factor for all heart failure and fatal heart failure, after adjusting for potential confounding variables and demonstrate that a prognostic cut-off value can be identified for all heart failure (>5.34 mg/dl) and for fatal heart failure (>4.89 mg/dl).

In vitro and in silico Xanthine Oxidase Inhibitory Activity of Selected Phytochemicals Widely Present in Various Edible Plants

AIM AND OBJECTIVE

The present study was designed to evaluate the xanthine oxidase (XO) inhibitory and antioxidant activities of 30 bioactive compounds present in edible food plants for the possible treatment of hyperuricemia.

MATERIALS AND METHODS

The XO inhibitory, SO and DPPH radical scavenging activities of selected dietary polyphenols were determined by using colorimetric assays. The molecular docking analysis was performed to evaluate the insight into inhibitory mode of action of bioactive compounds against XO.

RESULTS

The results show that apigenin, galangin, kaempferol, quercetin, genistein and resveratrol potently inhibit XO enzyme among all tested compounds. Flavonoids exhibit higher, anthocyanins and hydroxycinnamic acids moderate, maslinic acid, ellagic acid, salicylic acid, [6]-gingerol and flavan-3-ols showed weak XO inhibitory activity. The results of molecular docking study revealed that these bioactive compounds bind with the active site of XO and occupy the active site which further prevents the entrance of substrate and results in the inhibition of XO.

CONCLUSION

Inhibition of XO gives a robust biochemical basis for management of hyperuricemia, gout and other associated diseases via controlling uric acid synthesis.

Sex-specific association of hyperuricemia with cardiometabolic abnormalities in a military cohort: The CHIEF study

Hyperuricemia has been associated with metabolic syndrome, and the association with various cardiometabolic risk factors may be affected by sex.We made a cross-sectional examination in a military cohort of 6738 men and 766 women, aged 18 to 50 years of Taiwan in 2013 to 2014. Hyperuricemia were defined as serum uric acid levels ≥7.0 mg/dL for men and ≥5.7 mg/dL for women, respectively. Multivariable logistic regression analyses were used to determine the associations between hyperuricemia and various metabolic abnormalities.In the overall population, hyperuricemia was associated with high blood pressure (odds ratio [OR]: 1.59, and 95% confidence intervals: 1.42-1.77), low high-density lipoprotein (OR: 1.75, 1.56-1.97), high triglycerides (OR: 2.14, 1.90-2.42), high low-density lipoprotein (OR: 1.71, 1.51-1.93), high fasting plasma glucose (OR: 1.29, 1.13-1.48), and central obesity (OR: 2.85, 2.55-3.18) after adjusting for age and serum creatinine concentrations. However, the associations with atherogenic lipid profiles including high triglycerides and high low-density lipoprotein were merely significant in men but not in women. In addition, there was a tendency for a sex difference in the association of hyperuricemia and raised blood pressure ≥130/85 mm Hg, which was greater in women than that in men (OR: 2.92, 1.37-6.25 and 1.54, 1.37-1.72, respectively; P for interaction = .059).Our findings suggest that the association between hyperuricemia and various cardiometabolic abnormalities in young adults may differ by sex, possibly due to a regulation of sex hormones and uneven effects of uric acid at the same levels between sexes on lipid metabolisms and arterial stiffness.

Hyperuricemia is a Risk Factor for One-Year Overall Survival in Elderly Female Patients with Acute Coronary Syndrome

Background

Hyperuricemia is a risk factor for cardiovascular diseases, but the impact of hyperuricemia and sex-related disparities is not fully clear in elderly patients with acute coronary syndrome (ACS).

Objective

To investigate the association between hyperuricemia and 1-year all-cause mortality in elderly patients with ACS.

Methods

This retrospective cohort study included 711 consecutive ACS patients aged ≥75 years, hospitalized in our center between January 2013 and December 2017. Serum uric acid (sUA), in-hospital events, and 1-year follow-up were analyzed. Multivariable logistic regression models were used to explore the risk factors for in-hospital events and 1-year all-cause mortality.

Results

sUA levels were higher in males than in females (381.4 ± 110.1 vs. 349.3 ± 119.1 μmol/l, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%, P < 0.001). Prevalence of hypertension (80.5% vs. 72.6%,

Conclusions

Hyperuricemia is an independent risk factor for 1-year all-cause mortality in elderly female patients with ACS.

Serum Uric Acid Levels and Risk of Intracranial Atherosclerotic Stenosis: A Cross-Sectional Study

Elevated serum uric acid (SUA) has been reported to be associated with an increased risk of cardiovascular diseases, but the role of SUA in intracranial atherosclerosis remains unclear. To investigate the association between SUA and intracranial atherosclerotic stenosis (ICAS), we evaluated 1522 subjects (305 with ICAS, 1217 without ICAS) with magnetic resonance angiography (MRA). Subjects were classified into ten groups according to the deciles of the SUA level. The rate of ICAS reached a minimum in the seventh decile (6.0-6.3 mg/dL; reference group). After adjusting for confounding factors, multivariate logistic regression analysis demonstrated that both low SUA level (≤ 3.8 mg/dL; OR, 2.34; 95% CI, 1.29-4.39; p = 0.006) and high SUA level (≥ 7.8 mg/dL; OR, 2.10; 95% CI, 1.15-3.92; p = 0.017) conferred greater risk for ICAS. In multivariable analysis with a quadratic model which used SUA as a continuous variable, a U-shaped association between SUA and the rate of ICAS was confirmed (α > 0; p < 0.001). The estimated SUA level associated with the lowest rate of ICAS was 6.2 mg/dL. In conclusion, our findings suggest a U-shaped association between ICAS and SUA.

In silico design and synthesis of hesperitin derivatives as new xanthine oxidase inhibitors

Background

Hesperitin, a naturally occurring flavonoid was hybridized with phenolic acids to evaluate its potential to inhibit the activity of xanthine oxidase (XO), a key enzyme which catalyses xanthine to uric acid which is found to be associated with gout and many life style related disorders.

Objective

To develop new xanthine oxidase inhibitors from natural constituents along with antioxidant potential.

Method

In this report, we designed and synthesized hesperitin derivatives hybridized with natural phenolic acids to form ester linkage with the help of molecular docking. The synthesized compounds were evaluated for their antioxidant and xanthine oxidase inhibitory potential.

Results

The in vitro xanthine oxidase inhibitory activity and enzyme kinetics studies showed that hesperitin derivatives displayed a potential inhibition against XO in competitive manner with IC₅₀ value ranging from 9.0 to 23.15 µM and HET4 was revealed as most active derivative. Molecular simulation revealed that new hesperitin derivatives interacted with the amino acid residues SER1080, PHE798, GLN1194, ARG912, THR1083, ALA1078 and MET1038 located within the active cavity of XO. Results of antioxidant activity revealed that all the derivatives showed very good antioxidant potential.

Conclusion

Taking advantage of molecular docking, this hybridization of two natural constituent could lead to desirable xanthine oxidase inhibitors with improved activity.

New xanthine oxidase inhibitors from the fruiting bodies of Tyromyces fissilis

Excessive uric acid production, which causes gout and hyperuricemia, can be blocked by inhibiting xanthine oxidase (XO). However, some agents to block on XO often cause side effects, thereby necessitating the identification of new inhibitors. During the screening of XO inhibitors from various mushroom extracts, we found that a methanolic extract of the fruiting bodies of Tyromyces fissilis, an inedible and non-toxic fungus, showed inhibitory activity. Both n-hexane and ethyl acetate layers, obtained by partitioning this extract exhibited XO inhibitory activity. Subsequently, using an activity-guided separation method, eight active compounds (1-8) were isolated. The structures of five of the new compounds, 2-4, 6, and 7, were elucidated by spectral analysis and chemical derivatization. All compounds had a salicylic acid moiety with an aliphatic group at the C-6 position. Notably, 2-hydroxy-6-pentadecylbenzoic acid (1) showed the highest level of XO noncompetitive inhibition (58.9 ± 2.2% at 25 µM).

Isolation, characterization, and xanthine oxidase inhibitory activities of flavonoids from the leaves of Perilla frutescens

Phytochemical investigation of the water extract from the leaves of Perilla frutescens (Lamiaceae) led to the isolation of a new flavanone, a new chalcone, and a new aurone, namely, (2S)-5,7-dimethoxy-8,4'-dihydroxyflavanone (1), 2',4'-dimethoxy-4,5',6'-trihydroxychalcone (2), and (Z)-4,6-dimethoxy-7,4'-dihydroxyaurone (3), respectively. The structures were unambiguously elucidated on the basis of spectroscopic data. And the absolute configuration of 1 was determined by analysis of electronic circular dichroism spectrum. The isolated compounds were evaluated for their inhibitory effects on xanthine oxidase in vitro. Among them, 2 showed more potent activity than the positive control allopurinol, a well-known XO inhibitor clinically used for treatment of gout. Lineweaver-Burk transformation of the inhibition kinetics data demonstrated that it was a mixed-type inhibitor.[Formula: see text].

Association between serum uric acid and arterial stiffness in a low-risk, middle-aged, large Korean population: A cross-sectional study

We investigated the association between serum uric acid (SUA) and brachial ankle pulse wave velocity (baPWV) in an apparently healthy population. We performed a cross-sectional study on middle-aged Koreans who completed a yearly health-screening program between January and December 2014. Subjects with coronary artery disease, diabetes, or hypertension were excluded. Linear regression analyses were used to study the relationship between SUA and baPWV. Multiple adjustments were made for variables based on clinical or statistical significance. Of 66,917 study participants (38,170 men and 28,747 women), the mean age was 39.4 ± 6.7 years and the average SUA level was 5.23 ± 1.4 mg/dL. SUA values were higher in men than in women (6.1 ± 1.2 mg/dL vs. 4.1 ± 0.8 mg/dL). SUA was linearly associated with baPWV in women and in men (P < .001, respectively). Multiple regression analyses remained significant for women with a positive association with baPWV across SUA quintiles in a dose-response manner (P < .001) while no longer for men with a J-shaped association between SUA quintiles and baPWV. When SUA modeled continuously, baPWV rose by 12.413 cm/s in women (P < .001) and by 6.588 cm/s in men (P < .001) for each 1 mg/dL increase of SUA. In a low-risk, middle-aged, large Korean population, higher SUA levels could have an unfavorable impact on arterial stiffness as measured by baPWV, and this association was stronger in women than in men.

Antihyperuricemic effect of mangiferin aglycon derivative J99745 by inhibiting xanthine oxidase activity and urate transporter 1 expression in mice

A mangiferin aglycon derivative J99745 has been identified as a potent xanthine oxidase (XOD) inhibitor by previous in vitro study. This study aimed to evaluate the hypouricemic effects of J99745 in experimental hyperuricemia mice, and explore the underlying mechanisms. Mice were orally administered 600 mg/kg xanthine once daily for 7 days and intraperitoneally injected 250 mg/kg oxonic acid on the 7th day to induce hyperuricemia. Meanwhile, J99745 (3, 10, and 30 mg/kg), allopurinol (20 mg/kg) or benzbromarone (20 mg/kg) were orally administered to mice for 7 days. On the 7th day, uric acid and creatinine in serum and urine, blood urea nitrogen (BUN), malondialdehyde (MDA) content and XOD activities in serum and liver were determined. Morphological changes in kidney were observed using hematoxylin and eosin (H&E) staining. Hepatic XOD, renal urate transporter 1 (URAT1), glucose transporter type 9 (GLUT9), organic anion transporter 1 (OAT1) and ATP-binding cassette transporter G2 (ABCG2) were detected by Western blot and real time polymerase chain reaction (PCR). The results showed that J99745 at doses of 10 and 30 mg/kg significantly reduced serum urate, and enhanced fractional excretion of uric acid (FEUA). H&E staining confirmed that J99745 provided greater nephroprotective effects than allopurinol and benzbromarone. Moreover, serum and hepatic XOD activities and renal URAT1 expression declined in J99745-treated hyperuricemia mice. In consistence with the ability to inhibit XOD, J99745 lowered serum MDA content in hyperuricemia mice. Our results suggest that J99745 exerts urate-lowering effect by inhibiting XOD activity and URAT1 expression, thus representing a promising candidate as an anti-hyperuricemia agent.

The association between serum uric acid and asymptomatic intracranial arterial stenosis in middle-aged Koreans

BACKGROUND AND AIMS

Intracranial arterial stenosis (ICAS) is one of the most common causes of stroke, especially in Asians. Hyperuricemia has been associated with an increased risk of comorbidities such as metabolic syndrome or cardiovascular diseases. However, there are few studies focusing on the association between serum uric acid (SUA) levels and asymptomatic ICAS. The aim of this study was to explore the association between SUA and the prevalence of ICAS in middle-aged Korean health screening examinees.

METHODS AND RESULTS

A cross-sectional study was performed on 9417 males and 7755 females who underwent a comprehensive health examination including transcranial Doppler (TCD) ultrasonography. The association of SUA and ICAS was analyzed using multivariate logistic regression. The prevalence of ICAS among the total examinee population was 3.55%. In females, the multivariate-adjusted odds ratio for ICAS was 1.52 (confidence interval 1.13-2.04) in the 3rd quartile of SUA and 1.45 (1.05-2.00) in the highest quartile, compared to the reference (P for trend 0.008). This trend was evident in all clinically relevant subgroups evaluated, including women with low inflammation status. SUA was not significantly associated with the prevalence of ICAS among males. In a sensitivity analysis, the multivariate-adjusted odds ratio of middle cerebral artery stenosis in females was 1.60 (1.09-2.37) in the highest quartile compared to the reference (P for trend 0.023).

CONCLUSIONS

Higher SUA level was associated with increased risk of ICAS among middle-aged females but not males. A further cohort study is warranted to elucidate the effect of SUA on asymptomatic ICAS.

The role of urate-lowering treatment on cardiovascular and renal disease: evidence from CARES, FAST, ALL-HEART, and FEATHER studies

Hyperuricemia has long been known to cause gout, and has recently been correlated with cardiovascular disease, hypertension, and renal disease. In the last few years, several large clinical studies have confirmed that hyperuricemia is a significant and independent risk factor for hypertension, ischemic heart disease, and heart failure, after an extensive adjustment for almost all the possible confounding conditions. This article reviews published literature on the subject, and describes ongoing studies on the use of urate-lowering therapy for cardiovascular and renal diseases.

The role of hyperuricemia on vascular endothelium dysfunction

Hyperuricemia appears to be associated with an increased risk for cardiovascular disease and associated mortality. Population epidemiological data support a causal link between hyperuricemia and cardiovascular disease. Endothelium injury could be one of the potential mechanisms in hyperuricemia-induced cardiovascular disease. However, the specific role of uric acid (UA) in the impairment of vascular relaxation and its signal transduction pathway has not been examined. The authors investigated the role of UA on vascular relaxation, nitric oxide (NO) production and expression of proinflammatory cytokines. Brachial flow-mediated dilation and nitroglycerine-mediated dilation were measured by B-mode ultrasound with 10 megahertz linear-array transducer from 21 patients with hyperuricemia and 16 control subjects. Human umbilical vein endothelial cells (ECs) were incubated with UA (5-15 mg/dl) with or without nuclear factor (NF)-κB inhibitor II. Hyperuricemia inhibited brachial flow-mediated dilation. While UA significantly inhibited NO expression with time course- and dose- dependent manner in the cultured ECs, 10 mg/dl UA also increased expression of inflammation cytokine interleukin (IL)-6, IL-8 and tumor necrosis factor-α in vitro. These abnormalities were associated with UA-induced activation of transcription factor NF-κB. Furthermore, NF-κB inhibitor II prevented UA-induced reduction of NO and increased inflammation cytokines. These data suggested hyperuricemia-induced endothelium injury and vascular dysfunction by a reduction of NO and expression of inflammatory cytokines through the NF-κB pathway.

Uric acid promotes vascular stiffness, maladaptive inflammatory responses and proteinuria in western diet fed mice

OBJECTIVE

Aortic vascular stiffness has been implicated in the development of cardiovascular disease (CVD) and chronic kidney disease (CKD) in obese individuals. However, the mechanism promoting these adverse effects are unclear. In this context, promotion of obesity through consumption of a western diet (WD) high in fat and fructose leads to excess circulating uric acid. There is accumulating data implicating elevated uric acid in the promotion of CVD and CKD. Accordingly, we hypothesized that xanthine oxidase(XO) inhibition with allopurinol would prevent a rise in vascular stiffness and proteinuria in a translationally relevant model of WD-induced obesity.

MATERIALS/METHODS

Four-week-old C57BL6/J male mice were fed a WD with excess fat (46%) and fructose (17.5%) with or without allopurinol (125mg/L in drinking water) for 16weeks. Aortic endothelial and extracellular matrix/vascular smooth muscle stiffness was evaluated by atomic force microscopy. Aortic XO activity, 3-nitrotyrosine (3-NT) and aortic endothelial sodium channel (EnNaC) expression were evaluated along with aortic expression of inflammatory markers. In the kidney, expression of toll like receptor 4 (TLR4) and fibronectin were assessed along with evaluation of proteinuria.

RESULTS

XO inhibition significantly attenuated WD-induced increases in plasma uric acid, vascular XO activity and oxidative stress, in concert with reductions in proteinuria. Further, XO inhibition prevented WD-induced increases in aortic EnNaC expression and associated endothelial and subendothelial stiffness. XO inhibition also reduced vascular pro-inflammatory and maladaptive immune responses induced by consumption of a WD. XO inhibition also decreased WD-induced increases in renal TLR4 and fibronectin that associated proteinuria.

CONCLUSIONS

Consumption of a WD leads to elevations in plasma uric acid, increased vascular XO activity, oxidative stress, vascular stiffness, and proteinuria all of which are attenuated with allopurinol administration.

Effect of apple polyphenols on vascular oxidative stress and endothelium function: a translational study

SCOPE

We aimed examining apple polyphenols' effect on uricemia and endothelial function in a sample of overweight subjects.

METHODS AND RESULTS

This was a two-phased study. In vitro experiment aimed to evaluate apple polyphenols' ability to lower uric acid in comparison with allopurinol. In vivo study consisted in a randomized, double-blind, parallel placebo-controlled clinical trial involving 62 overweight volunteers with suboptimal values of fasting plasma glucose (100 mg/dL≤FPG≤125 mg/dL), randomized to 300 mg apple polyphenols or placebo for 8 weeks. Apple polyphenols extract inhibited xanthine oxidase activity, with an IC50 = 130 ± 30 ng/mL; reducing uric acid production with an IC50 = 154 ± 28 ng/mL. During the trial, after the first 4 weeks of treatment, FPG decreased in the active treated group (-6.1%, p < 0.05), while no significant changes were observed regarding the other hematochemistry parameters. After 4 more weeks of treatment, active-treated patients had an improvement in FPG compared to baseline (-10.3%, p < 0,001) and the placebo group (p < 0,001). Uric acid (-14.0%, p < 0.05 versus baseline; p < 0.05 versus placebo) and endothelial reactivity (0.24±0.09, p = 0.009 versus baseline; p < 0.05 versus placebo) significantly improved too.

CONCLUSION

In vivo, apple polyphenols extract has a positive effect on vascular oxidative stress and endothelium function and reduce FPG and uric acid by inhibiting xanthine oxidase, as our In vitro experiment attests.

An evidence-based review on urate-lowering treatments: implications for optimal treatment of chronic hyperuricemia

Several studies suggest that chronic hyperuricemia, the main precursor of gout, is involved in the pathogenesis of different systemic disorders that affect cardiovascular and renal systems, such as hypertension, obesity, hypercholesterolemia, atherosclerosis, metabolic syndrome, chronic heart failure, and chronic kidney disease. Recent epidemiological evidence has shown an increasing trend in the prevalence of hyperuricemia and gout in the Western world: a number of population-based studies estimate a prevalence of up to 21% for hyperuricemia and 1%–4% for gout. As such, early detection and careful management of this pathological condition is required, starting from lifestyle changes (mainly based on a diet low in red meat, sugars, and alcoholic beverages, with increased intake of vegetables, water, and vitamin C sources), adding specific drugs to lead serum uric acid (SUA) levels under the target value of 7 mg/dL. In particular, nonselective and selective XO inhibitors (allopurinol, oxypurinol, febuxostat) reduce SUA levels and the overproduction of reactive oxygen species, mainly related to XO overactivity that often causes inflammatory damage to the vascular endothelium. The effect of lowering SUA levels via XO inhibition includes an attenuation of oxidative stress and related endothelial dysfunction that largely contribute to the pathophysiology of metabolic syndrome and cardiovascular diseases. Therefore, the inhibition of XO overactivation seems to be an excellent therapeutic option to limit the harmful effects of excess UA and reactive oxygen species. In conclusion, rapid diagnosis and correct therapy for hyperuricemia may also improve the prevention and/or treatment of serious and multifactorial diseases. The available evidence supports the importance of promoting new experimental clinical trials to confirm the emerging antioxidant role of XO inhibitors, which could effectively contribute to cardiovascular and chronic kidney disease prevention.

Hyperuricemia is associated with increased hospitalization risk and healthcare costs: Evidence from an administrative database in Italy

BACKGROUND AND AIM

Chronic hyperuricemia is responsible for a relevant burden of articular diseases and cardio-nephrometabolic disorders. We evaluated the effect of high serum uric acid (SUA) levels on hospitalization risk and mortality and on healthcare costs in a real-life setting.

METHODS AND RESULTS

We conducted a retrospective analysis using a large administrative database and a clinical registry among 112,170 subjects from three Italian local health units. Individuals were divided into four groups according to their SUA levels: <6 mg/dL (66.5%), >6 mg/dL and ≤7 mg/dL (19.3%), >7 mg/dL and ≤8 mg/dL (8.7%), and >8 mg/dL (5.5%). Compared to those with SUA level of <6 mg/dL, the risk of hospitalization related to gout and/or nephrolithiasis was higher in the three groups of patients with higher SUA levels (1.51, P = 0.100; 2.21, P = 0.005; and 1.17, P = 0.703, respectively). A similar trend was also observed for hospitalization due to chronic kidney disease (CKD) (1.31, P < 0.001; 1.40, P < 0.001; and 2.18, P < 0.001, respectively) and cardiovascular disease (CVD) (1.08, P < 0.001; 1.23, P < 0.001; and 1.67, P < 0.001, respectively) and for all-cause mortality (0.97, P = 0.309; 1.21, P < 0.001; and 2.15, P < 0.001). The mean annual healthcare costs were higher in patients with higher SUA level (€2752, €2957, €3386, and €4607, respectively) mainly because of a progressive increase in hospitalization costs per patient (from € 1515 for SUA <6 mg/dL to € 3096 for SUA >8 mg/dL).

CONCLUSIONS

Increased SUA levels are associated with an increased risk of hospitalizations related to hyperuricemia, CKD, and CVDs and total mortality, and consequently with higher total healthcare costs and hospitalization costs per patient.

Uric Acid Amplifies Aβ Amyloid Effects Involved in the Cognitive Dysfunction/Dementia: Evidences From an Experimental Model In Vitro

There is still a considerable debate concerning whether uric acid is neuroprotective or neurotoxic agent. To clarify this topic, we tested the effects of uric acid on neuronal cells biology by using differentiated SHSY5Y neuroblastoma cells incubated with amyloid β to reproduce an in vitro model of Alzheimer's disease. The incubation of cells with uric acid at the dose of 40 µM or higher significantly reduced cell viability and potentiated the proapoptotic effect of amyloid β. Finally, uric acid enhanced the generation of 4-hydroxynonenal and the expression of PPARβ/δ promoted by amyloid β, indicating a prooxidant effects. In conclusion, uric acid could exert a detrimental influence on neuronal biology being this influence further potentiated by the concomitant exposure to neurotoxic stimuli. This effect is evident for uric acid concentrations close to those achievable in cerebrospinal fluid in presence of mild hyperuricemia thus suggesting a potential role of uric acid in pathophysiology of cognitive dysfunction. These effects are influenced by the concentrations of uric acid and by the presence of favoring conditions that commonly occur in neurodegenerative disorders and well as in the aging brain, including increased oxidative stress and exposure to amyloid β. J. Cell. Physiol. 232: 1069-1078, 2017. © 2016 Wiley Periodicals, Inc.

Hyperuricemia-Related Diseases and Xanthine Oxidoreductase (XOR) Inhibitors: An Overview

Uric acid is the final oxidation product of purine metabolism in humans. Xanthine oxidoreductase (XOR) catalyzes oxidative hydroxylation of hypoxanthine to xanthine to uric acid, accompanying the production of reactive oxygen species (ROS). Uric acid usually forms ions and salts known as urates and acid urates in serum. Clinically, overproduction or under-excretion of uric acid results in the elevated level of serum uric acid (SUA), termed hyperuricemia, which has long been established as the major etiologic factor in gout. Accordingly, urate-lowering drugs such as allopurinol, an XOR-inhibitor, are extensively used for the treatment of gout. In recent years, the prevalence of hyperuricemia has significantly increased and more clinical investigations have confirmed that hyperuricemia is an independent risk factor for cardiovascular disease, hypertension, diabetes, and many other diseases. Urate-lowering therapy may also play a critical role in the management of these diseases. However, current XOR-inhibitor drugs such as allopurinol and febuxostat may have significant adverse effects. Therefore, there has been great effort to develop new XOR-inhibitor drugs with less or no toxicity for the long-term treatment or prevention of these hyperuricemia-related diseases. In this review, we discuss the mechanism of uric acid homeostasis and alterations, updated prevalence, therapeutic outcomes, and molecular pathophysiology of hyperuricemia-related diseases. We also summarize current discoveries in the development of new XOR inhibitors.