Comparative effects of topiroxostat and febuxostat on arterial properties in hypertensive patients with hyperuricemia

Effect of the Xanthine Oxidase Inhibitor Febuxostat on the Cardio-Ankle Vascular Index in Asymptomatic Patients with Hyperuricemia and Liver Dysfunction: A Sub-Analysis of the PRIZE Study

AIMS

The effect of uric acid (UA)-lowering therapy with xanthine oxidoreductase (XOR) inhibitors on the development of cardiovascular disease requires further investigation. This study aimed to evaluate the long-term effects of febuxostat on arterial stiffness, focusing on liver function.

METHODS

The PRIZE study involved random assignment of patients with asymptomatic hyperuricemia to receive either add-on febuxostat treatment (febuxostat group) or non-pharmacological treatment (control group). Of the 514 participants, 23 and 14 patients in the febuxostat and control groups, respectively, underwent assessment of arterial stiffness using the cardio-ankle vascular index (CAVI). The participants in each group were further grouped on the basis of their baseline alanine aminotransferase (ALT) or aspartate aminotransferase (AST) levels (above or below the media value or 30 U/L). The primary endpoint was the change in the CAVI from baseline to 12 and 24 months.

RESULTS

Overall, no significant differences were found between the control and febuxostat groups in the least-squares mean estimates of changes in CAVI at 24 months (mean between-group difference, -0.41 [95% CI, -1.05 to 0.23]; p=0.204). However, there were significant differences in participants with higher baseline ALT or AST levels above 30 U/L at 24 months (mean between-group difference, -1.12 [95% CI, -2.23 to -0.01]; p=0.048 for ALT ≥ 30 U/L and -1.08 [95% CI, -2.13 to -0.03]; p=0.044 for AST ≥ 30 U/L).

CONCLUSIONS

Two-year treatment with febuxostat demonstrated a beneficial effect on CAVI in patients with hyperuricemia and liver dysfunction.

Association between serum uric acid levels and arterial stiffness in patients with psoriasis

This study examined the association between serum uric acid levels (SUA) and arterial stiffness in patients with psoriasis vulgaris. A cross-sectional study was conducted on 205 consecutive patients with psoriasis vulgaris who visited the Dermatology Clinic of China-Japan Friendship Hospital between March 2022 and July 2024. Arterial stiffness was assessed by measuring brachial-ankle pulse wave velocity (baPWV). The patients were divided into four groups (Q1, Q2, Q3, and Q4) according to the quartiles of SUA levels. The clinical data of each group were analysed and compared. Multivariate linear regression was employed to investigate the linear correlation between SUA levels and baPWV, and subgroup analyses were performed. There were differences in sex ratio, body mass index (BMI), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), homocysteine (HCY), and baPWV levels between the four groups. After adjustment for confounders, a significant linear correlation between SUA and baPWV remained, with baPWV increasing by 0.519 cm/s for every 1 mmol/L increase in SUA (β=0.519, 95%CI: 0.176-0.862, P = 0.003). BaPWV was significantly higher in the Q4 group compared with the lowest Q1 group (β=137.043, 95%CI: 43.574-230.511, P = 0.004). Subgroup analysis showed that the positive correlation between SUA and baPWV was more significant in the subgroups of males, moderate-to-severe psoriasis, no history of hypertension, no history of hyperlipidaemia, non-smokers and BMI ≥ 24 kg/m2. In patients with psoriasis, high SUA is associated with increased baPWV. Early screening and intervention of cardiovascular risk should be emphasised. Further studies are needed to establish a causal relationship and to guide treatment.

Comparison of the incidence of proteinuria and changes in eGFR among febuxostat and topiroxostat users

BACKGROUND

Febuxostat and topiroxostat are non-purine selective xanthine oxidoreductase inhibitors commonly used for hyperuricaemia treatment in Japan. However, comparative data on the effects of febuxostat and topiroxostat on renal function and proteinuria are limited. This study compared proteinuria incidence and changes in the estimated glomerular filtration rate (eGFR) among prevalent febuxostat and topiroxostat users.

METHODS

We conducted a retrospective cohort study using databases provided by DeSC Healthcare, Inc. (Tokyo, Japan). We identified 17,446 individuals (11.8% women; mean age 67.4 years) with eGFR ≥ 30 mL/min/1.73 m2 and no history of cardiovascular disease or proteinuria at baseline. Separate analyses were performed for individuals with eGFR < 60 mL/min/1.73 m2 and those with eGFR ≥ 60 mL/min/1.73 m2. The adjusted hazard ratio (HR) for proteinuria incidence in topiroxostat users compared with febuxostat users was assessed using the Cox model. Changes in eGFR were compared between the two groups using multiple regression analysis.

RESULTS

During the mean follow-up period of 1.79 years, 1,433 participants developed proteinuria. In non-diabetic individuals with eGFR ≥ 60 mL/min/1.73 m2, the adjusted HR for proteinuria incidence in topiroxostat users compared with febuxostat users was 0.60 (95% confidence interval, 0.40-0.91; p = 0.016). No significant differences were observed in eGFR changes between the two groups with eGFR < 60 and ≥ 60 mL/min/1.73 m2.

CONCLUSION

Topiroxostat prevalent users had a lower risk of proteinuria than febuxostat prevalent users in non-diabetic individuals with eGFR ≥ 60 mL/min/1.73 m2. Our findings suggest that topiroxostat might be more effective than febuxostat in preventing proteinuria in non-diabetic individuals with eGFR ≥ 60 mL/min/1.73 m2.

Approaches and Challenges in Managing Treatment-Resistant Hypertension: A Case Report

Treatment-resistant hypertension (TRH) is defined by consistently elevated blood pressure readings unresponsive to medical management. In clinical practice, it poses a significant challenge due to the intertwining variables that may cause the issue to persist such as lifestyle, genetics, and other comorbidities, as opposed to simple medication non-adherence. This report describes the case of a 68-year-old female patient presenting for a routine follow-up with persistently elevated ambulatory blood pressure readings. The patient was compliant with her medication regimen and followed lifestyle modification guidelines. Physical exam and review of systems showed no changes relative to previous visits. Laboratory findings were insignificant other than a low estimated glomerular filtration rate (eGFr) of 52. The patient's condition was stable but required further management to bring blood pressure readings into or closer to optimal range. This case looks at how the patient was managed and the rationale behind these decisions based on the patient's clinical history. It also emphasizes the importance of regular monitoring and constant adjustment of medical management to treatment for patients with TRH due to its unrelenting nature.

Hyperuricemia research progress in model construction and traditional Chinese medicine interventions

Hyperuricemia (HUA), a severe metabolic disease derived from purine metabolism disorder, will lead to abnormally increased serum uric acid (SUA) levels in the body. Studies have shown that HUA is highly related to gout, hypertension, diabetes, coronary heart disease, chronic kidney diseases, and so on. Traditional Chinese medicine (TCM) shows excellent results in treating HUA because of its unique advantages of multi-metabolites and multi-targets. This article reports on the use of TCM components for uric acid (UA)-lowering activity with excellent efficacy and low side effects based on established HUA models. This work summarizes the advantages and limitations of various HUA disease models for efficacy evaluation. Applications of TCM in HUA treatment have also been discussed in detail. This paper reveals recent research progress on HUA in constructing evaluation models and systematic TCM interventions. It will provide a scientific reference for establishing the HUA model and suggest future TCM-related HUA studies.

A Possible Therapeutic Application of the Selective Inhibitor of Urate Transporter 1, Dotinurad, for Metabolic Syndrome, Chronic Kidney Disease, and Cardiovascular Disease

The reabsorption of uric acid (UA) is mainly mediated by urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) in the kidneys. Dotinurad inhibits URAT1 but does not inhibit other UA transporters, such as GLUT9, ATP-binding cassette transporter G2 (ABCG2), and organic anion transporter 1/3 (OAT1/3). We found that dotinurad ameliorated the metabolic parameters and renal function in hyperuricemic patients. We consider the significance of the highly selective inhibition of URAT1 by dotinurad for metabolic syndrome, chronic kidney disease (CKD), and cardiovascular disease (CVD). The selective inhibition of URAT1 by dotinurad increases urinary UA in the proximal tubules, and this un-reabsorbed UA may compete with urinary glucose for GLUT9, reducing glucose reabsorption. The inhibition by dotinurad of UA entry via URAT1 into the liver and adipose tissues increased energy expenditure and decreased lipid synthesis and inflammation in rats. Such effects may improve metabolic parameters. CKD patients accumulate uremic toxins, including indoxyl sulfate (IS), in the body. ABCG2 regulates the renal and intestinal excretion of IS, which strongly affects CKD. OAT1/3 inhibitors suppress IS uptake into the kidneys, thereby increasing plasma IS, which produces oxidative stress and induces vascular endothelial dysfunction in CKD patients. The highly selective inhibition of URAT1 by dotinurad may be beneficial for metabolic syndrome, CKD, and CVD.

Urate-Lowering Drugs and Muscle Injury: A Systematic Review and Network Meta-Analysis

Several urate-lowering drugs have been linked to muscle injury. This study investigated the association of oral urate-lowering drugs with the risk of muscle injury by performing a network meta-analysis of randomized and non-randomized controlled trials. A systematic search of MEDLINE, via PubMed, the ClinicalTrials.gov website, and the Cochrane Central Register of Controlled Trials was conducted to identify relevant studies with a primary outcome of "all muscle injuries." A random-effects model was used to perform a frequentist network meta-analysis to estimate whether there was significant heterogeneity among the studies. In total, 32 studies including 28,327 participants with 2694 (9.5%) "all muscle injuries" were assessed, and the overall risk of bias was judged to be low to moderate. No statistically significant differences were found between placebo and 6 urate-lowering therapies: allopurinol (risk ratio, RR, 1.05; 95% confidence interval, 95%CI, 0.63-1.73), febuxostat (RR 1.10, 95%CI 0.71-1.70), lesinurad (RR 7.00, 95%CI 0.31-160.36), lesinurad concomitant with allopurinol (RR 0.85, 95%CI 0.34-2.11), lesinurad concomitant with febuxostat (RR 1.97, 95%CI 0.55-7.03), and topiroxostat (RR 0.99, 95%CI 0.37-2.65). The findings suggest that there is little need to consider the risk of muscle injury when using urate-lowering drugs in the clinical setting.

Relationship of Serum Uric Acid with Kidney Function Decline Mediated by Systemic Arterial Stiffness: A Retrospective Cohort Study in Japan

Hyperuricemia is associated with kidney function decline (KFD), although whether hyperuricemia directly causes nephrotoxicity or is indirectly mediated by systemic arterial stiffening remains unclear. We examined the detailed relationship of serum uric acid (SUA) with KFD and potential mediation by arterial stiffness. Study population was 27,648 urban residents with an estimated glomerular filtration rate (eGFR) of ≥60 mL/min/1.73 m2 at baseline, and they participated in a median of three consecutive annual health examinations. Arterial stiffness was assessed using cardio-ankle vascular index (CAVI). KFD was defined as a decrease in eGFR to below 60. Multivariate analysis showed an association between baseline SUA and CAVI independent of eGFR. During the study period, 6.6% of participants developed KFD. Stratified analysis revealed a linear relationship between the contribution of CAVI or SUA and KFD. ROC analysis determined a cutoff CAVI of 8.0 (males) or 7.9 (females) and a cutoff SUA of 6.3 (males) or 4.5 mg/dL (females) for predicting KFD. The linkage between SUA and CAVI was associated with a greater increase in the hazard ratio for KFD with an increase in SUA. CAVI showed the mediating effect on the relationship of SUA with KFD after an adjustment for confounders. SUA was associated positively with CAVI-mediated KFD. Further studies should verify whether intensive SUA-lowering treatment prevents KFD via improving vascular function.

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.

Impact of Hyper- and Hypo-Uricemia on Kidney Function

Uric acid (UA) forms monosodium urate (MSU) crystals to exert proinflammatory actions, thus causing gout arthritis, urolithiasis, kidney disease, and cardiovascular disease. UA is also one of the most potent antioxidants that suppresses oxidative stress. Hyper andhypouricemia are caused by genetic mutations or polymorphism. Hyperuricemia increases urinary UA concentration and is frequently associated with urolithiasis, which is augmented by low urinary pH. Renal hypouricemia (RHU) is associated with renal stones by increased level of urinary UA, which correlates with the impaired tubular reabsorption of UA. Hyperuricemia causes gout nephropathy, characterized by renal interstitium and tubular damage because MSU precipitates in the tubules. RHU is also frequently associated with tubular damage with elevated urinary beta2-microglobulin due to increased urinary UA concentration, which is related to impaired tubular UA reabsorption through URAT1. Hyperuricemia could induce renal arteriopathy and reduce renal blood flow, while increasing urinary albumin excretion, which is correlated with plasma xanthine oxidoreductase (XOR) activity. RHU is associated with exercise-induced kidney injury, since low levels of SUA could induce the vasoconstriction of the kidney and the enhanced urinary UA excretion could form intratubular precipitation. A U-shaped association of SUA with organ damage is observed in patients with kidney diseases related to impaired endothelial function. Under hyperuricemia, intracellular UA, MSU crystals, and XOR could reduce NO and activate several proinflammatory signals, impairing endothelial functions. Under hypouricemia, the genetic and pharmacological depletion of UA could impair the NO-dependent and independent endothelial functions, suggesting that RHU and secondary hypouricemia might be a risk factor for the loss of kidney functions. In order to protect kidney functions in hyperuricemic patients, the use of urate lowering agents could be recommended to target SUA below 6 mg/dL. In order to protect the kidney functions in RHU patients, hydration and urinary alkalization may be recommended, and in some cases an XOR inhibitor might be recommended in order to reduce oxidative stress.

Science Popularization Interventions on Rational Medication in Patients with Hyperuricemia

Objective: This research aimed to explore the science of population intervention in the rational medication treatment of hyperuricemia patients in China. The research model was designed to determine interventions from three dimensions of science propylitization (empirical evidence, logical reasoning, and skeptical attitude). Methods: The data for this research was collected from hyperuricemia patients in China with a survey-based questionnaire. A partial least square-structural equation modeling statistical method was used for data evaluation. Results: The research investigated that science popularization can strongly influence hyperuricemia patients' rational medication with empirical evidence, logical reasoning, and a skeptical attitude. Furthermore, the research asserted that more focus on scientific knowledge of hyperuricemia patients can improve their health further. Conclusion: Theoretically, this research would have wider implications. First, the research model was based on science popularization interventions which is a novel contribution to the relationship with rational medication. Second, the practical implications of this study would lie in science population interventions improving the rational medications for hyperuricemia patients. Besides, this research asserted a few future directions for scholars to contribute and determine the impact of further variables to enhance the model of science popularization in relationship with rational medication.

The Effects of Topiroxostat, a Selective Xanthine Oxidoreductase Inhibitor, on Arterial Stiffness in Hyperuricemic Patients with Liver Dysfunction: A Sub-Analysis of the BEYOND-UA Study

Background: The effects of uric acid (UA)-lowering therapy with xanthine oxidoreductase (XOR) inhibitors on the development of cardiovascular diseases remain controversial. Based on recent findings that plasma XOR activity increased in liver disease conditions, we conducted a sub-analysis of the BEYOND-UA study to examine the differential effects of topiroxostat on arterial stiffness based on liver function in hyperuricemic individuals with hypertension. Methods: Sixty-three subjects treated with topiroxostat were grouped according to baseline alanine aminotransferase (ALT) levels (above or below cut-off values of 22, 30, or 40 U/L). The primary endpoint was changes in the cardio-ankle vascular index (CAVI) from baseline to 24 weeks. Results: Significant reductions in CAVI during topiroxostat therapy occurred in subjects with baseline ALT ≥30 U/L or ≥40 U/L, and significant between-group differences were detected. Brachial-ankle pulse wave velocity significantly decreased in the ALT-high groups at all cut-off values. Reductions in morning home blood pressure and serum UA were similar regardless of the baseline ALT level. For eleven subjects with available data, ALT-high groups showed high plasma XOR activity, which was significantly suppressed by topiroxostat. Conclusions: Topiroxostat improved arterial stiffness parameters in hyperuricemic patients with liver dysfunction, which might be related to its inhibitory effect on plasma XOR.

Febuxostat and renal outcomes: post-hoc analysis of a randomized trial

Effect of urate-lowering on renal outcomes in patients at high-risk for cardiovascular disease with hyperuricemia without gout is not known. We conducted a post hoc analysis of a randomized trial (Febuxostat for Cerebral and　CaRdiorenovascular Events PrEvEntion StuDy [FREED]). The FREED trial enrolled 1070 asymptomatic, hyperuricemic elderly patients with at least one risk factor for cardiovascular disease, divided into febuxostat (n = 537) and non-febuxostat (n = 533) groups. We compared the effect of these treatments on renal outcomes including 40% decline in estimated glomerular filtration rate, new onset of microalbuminuria and development or worsening macroalbuminuria. The relative risk of developing or worsening macroalbuminuria was 56% lower in the febuxostat group (hazard ratio, 0.44; 95% CI, 0.24-0.82; P = 0.0098). However, the risks for other outcomes were comparable. In patients with asymptomatic hyperuricemia without gout, febuxostat reduces the risk of development or worsening of macroalbuminuria.

Effect of Topiroxostat on Reducing Oxidative Stress in the Aorta of Streptozotocin-Induced Diabetic Rats

Xanthine oxidoreductase exists both intracellularly and extracellularly and induces vascular injury by producing reactive oxygen species (ROS). Here, we investigated the effects and mechanism of action of topiroxostat, a xanthine oxidase inhibitor, on ROS using an animal model of type 1 diabetes with persistent hyperglycemia. Six-week-old male Sprague-Dawley rats were administered 50 mg/kg streptozotocin to induce diabetes; at 8 weeks of age, animals were administered topiroxostat (0.3, 1, or 3 mg/kg) for 2 weeks through mixed feeding after which the aorta was sampled. The production of superoxide, a type of ROS, was measured by chemiluminescence and dihydroethidium staining. Cytotoxicity was evaluated by nitrotyrosine staining. Topiroxostat at 3 mg/kg significantly decreased blood urea nitrogen, e-selectin, urinary malondialdehyde, and the urinary albumin/creatinine ratio compared with the streptozotocin group. Superoxide production by xanthine oxidase anchored to the cell membrane was significantly decreased by topiroxostat at both 1 mg/kg and 3 mg/kg compared with the streptozotocin group. Dihydroethidium staining revealed no significant effect of topiroxostat administration on superoxide production. The fluorescence intensity of nitrotyrosine staining was significantly suppressed by 3 mg/kg topiroxostat. Topiroxostat was found to inhibit the production of ROS in the thoracic aorta and suppress vascular endothelial damage. The antioxidant effect of topiroxostat appears to be exerted via the inhibition of anchored xanthine oxidase.

Association of serum uric acid with the risk of developing hypertension: A prospective cohort study with mediation analysis

Elevated serum uric acid (SUA) is associated with the incidence of hypertension, but whether relevant metabolic factors have mediating effects is not certain. Our study was based on a functional community cohort established in Beijing. In 2015, a total of 7482 individuals without hypertension were recruited and followed up until 2019. Multivariate logistic regression analysis was used to investigate the association between SUA and hypertension. Cross-lagged panel analysis and mediation analysis were used to explore the effects of metabolic factors on the association between SUA and incident hypertension. During the average 4-year follow-up, the cumulative incidence of hypertension was 10.9% (n = 580). SUA was an independent risk factor for hypertension, and the RRs (95% CI) for subjects with baseline SUA levels in quartile 2, quartile 3 and quartile 4 were 1.20 (0.88-1.63), 1.50 (1.10-2.05), and 1.57 (1.11-2.22) compared to those in quartile 1, respectively. The cross-lagged panel analysis showed that the increases in Cr, TG, LDL, ALT, AST and WBC occurred after SUA increased (P < 0.001). Among these factors, TG, WBC and ALT played an intermediary role in both men (TG: 14.76%; WBC: 11.61%; ALT: 15.93%) and women (TG: 14.55%; WBC: 8.55%; ALT: 6.89%). The elevated SUA concentration was an independent risk factor for hypertension in the Chinese population, and TG, WBC and ALT had important mediating effects on the association between SUA and hypertension.

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.

Review of Urate-Lowering Therapeutics: From the Past to the Future

We reviewed all currently available ULT, as well as any medications in development using following databases: United States Food and Drug Administration (FDA), European Medicines Agency (EMA), Japanese Pharmaceutical and Medical Devices Agency (PMDA), and ClinicalTrials.gov. We identified a total of 36 drugs, including 10 approved drugs, 17 in clinical testing phases, and 9 in preclinical developmental phases. The 26 drugs currently undergoing testing and development include 5 xanthine oxidase inhibitors, 14 uricosurics, 6 recombinant uricases, and one with multiple urate-lowering mechanisms of action. Herein, we reviewed the benefit and risk of each drug summarizing currently available drugs. New trials of uricosuric agents are underway to develop the new indication. New drugs are going on to improve the potency of recombinant uricase and to develop the new route administration of such as oral formulation. This review will provide valuable information on the properties, indications, and limitations of ULTs.

The reality of treatment for hyperuricemia and gout in Japan: A historical cohort study using health insurance claims data

Hyperuricemia causes gout and has also been associated with metabolic syndrome and cardiovascular disease. Uric acid‐lowering drugs (ULDs) are used to reduce uric acid levels for the treatment of hyperuricemia and gout. However, there is a lack of robust and real‐world data on the history and treatment of patients with newly diagnosed hyperuricemia or gout in Japan. This retrospective, longitudinal, historical cohort study determined the characteristics of patients with hyperuricemia and/or gout, and prescription of, and adherence to, ULDs using data from the JMDC Claims Database. The primary evaluation population included 64 677 patients with newly diagnosed hyperuricemia and/or gout. Of these, only 26 501 (41.0%) had a prescription for ULDs at diagnosis. Even when ULDs were prescribed, the persistence rate of prescriptions declined over time, with a 54.4% persistence rate for ULDs at 12 months after the index diagnosis. In subgroups of patients with or without hypertension and diabetes, the rate of ULD prescription continuation was significantly higher in those with comorbidities than in those without (76.8% vs. 42.6% in those with vs. without hypertension, and 78.7% vs. 52.2% in those with vs. without diabetes). These finding suggest that therapeutic interventions to lower serum uric acid levels are under‐utilized for patients with newly diagnosed hyperuricemia and/or gout in Japan.

Differential effect of a xanthine oxidase inhibitor on arterial stiffness and carotid atherosclerosis: a subanalysis of the PRIZE study

Atherosclerosis and arterial stiffness are phenotypes of atherosclerotic vascular damage. Atherosclerosis originates from endothelial vascular damage and forms focal morphological lesions; arterial stiffness originates from diffuse medial-layer damage in the arterial tree. Thus, the two phenomena reflect different facets of atherosclerotic vascular damage, and they both gradually progress. We conducted a subanalysis to compare the long-term effects of febuxostat on atherosclerosis and arterial stiffness in the PRIZE study (a multicenter, prospective, randomized, open-label, blinded-endpoint clinical trial to examine the effect of febuxostat on carotid atherosclerosis). Among 514 study participants, arterial stiffness parameters (brachial-ankle pulse wave velocity or cardio-ankle vascular index) were obtained at baseline, 12 months, and 24 months in 100 subjects. Among them, 48 subjects were allocated to the control group (i.e., nonpharmacological lifestyle modification for hyperuricemia), and 52 subjects were allocated to the febuxostat treatment group. While the decrease in serum uric acid was greater in the febuxostat group than in the control group, the adjusted percentage decrease in arterial stiffness parameters at month 24 was greater in the febuxostat group than in the control group, with a mean between-group difference (febuxostat - control) of -5.099% (95% confidence interval (CI) -10.009% to -0.188%, p = 0.042). Thus, long-term treatment with febuxostat may exert beneficial effects on arterial stiffness without improving carotid atherosclerosis. A long-term study to examine the effect of febuxostat on cardiovascular outcomes related to increased arterial stiffness is warranted.

Impact of hyperuricemia on chronic kidney disease and atherosclerotic cardiovascular disease

Hyperuricemia is caused by reduced renal/extrarenal excretion and overproduction of uric acid. It is affected by genetic predisposition related to uric acid transporters and by visceral fat accumulation due to overnutrition. The typical symptomatic complication of hyperuricemia is gout caused by monosodium urate crystals. Accumulated evidence from epidemiological studies suggests that hyperuricemia is also a risk factor for hypertension, chronic kidney disease (CKD) and atherosclerotic cardiovascular disease (CVD). However, it remains to be determined whether urate-lowering therapy for asymptomatic patients with hyperuricemia is effective in preventing CKD or CVD progression. This mini review focuses mainly on recent papers investigating the relationship between hyperuricemia and CKD or CVD and studies of urate-lowering therapy. Accumulated studies have proposed mechanisms of renal damage and atherosclerosis in hyperuricemia, including inflammasome activation, decreased nitric oxide bioavailability and oxidative stress induced by uric acid, urate crystals and xanthine oxidoreductase (XOR)-mediated reactive oxygen species. Since patients with hyperuricemia are a heterogeneous population with complex pathologies, it may be important to assess whether an outcome is the result of decreasing serum uric acid levels or an inhibitory effect on XOR. To clarify the impact of hyperuricemia on CKD and CVD progression, high-quality and detailed clinical and basic science studies of hyperuricemia and purine metabolism are needed.

Increased plasma XOR activity induced by NAFLD/NASH and its possible involvement in vascular neointimal proliferation

Xanthine oxidoreductase (XOR) is an enzyme that catalyzes hypoxanthine to xanthine and xanthine to uric acid, respectively. However, the underlying mechanisms of increased plasma XOR and its pathological roles in systemic diseases, such as atherosclerosis, are not fully understood. In this study, we found that changes in plasma XOR activity after bariatric surgery closely associated with those in liver enzymes, but not with those in BMI. In a mouse model of nonalcoholic fatty liver disease/steatohepatitis (NAFLD/NASH), plasma XOR activity markedly increased. Besides, purine catabolism was accelerated in the plasma per se of NASH mice and human patients with high XOR activity. In our NASH mice, we observed an increased vascular neointima formation consisting of dedifferentiated vascular smooth muscle cells (SMCs), which was significantly attenuated by topiroxostat, a selective XOR inhibitor. In vitro, human liver S9–derived XOR promoted proliferation of SMCs with phenotypic modulation and induced ROS production by catabolizing hypoxanthine released from human endothelial cells. Collectively, the results from human and mouse models suggest that increased plasma XOR activity, mainly explained by excess hepatic leakage, was involved in the pathogenesis of vascular injury, especially in NAFLD/NASH conditions.

Independent association of plasma xanthine oxidoreductase activity with hypertension in nondiabetic subjects not using medication

Xanthine oxidoreductase (XOR), a rate-limiting and catalyzing enzyme of uric acid formation in purine metabolism, is involved in reactive oxygen species generation. Plasma XOR activity has been shown to be a novel metabolic biomarker related to obesity, liver dysfunction, hyperuricemia, dyslipidemia, and insulin resistance. However, the association between plasma XOR activity and hypertension has not been fully elucidated. We investigated the association of hypertension with plasma XOR activity in 271 nondiabetic subjects (male/female: 119/152) who had not taken any medications in the Tanno-Sobetsu Study, a population-based cohort. Males had higher plasma XOR activity than females. Plasma XOR activity was positively correlated with mean arterial pressure (r = 0.128, P = 0.036). When the subjects were divided by the presence and absence of hypertension into an HT group (male/female: 34/40) and a non-HT group (male/female: 85/112), plasma XOR activity in the HT group was significantly higher than that in the non-HT group (median: 39 vs. 28 pmol/h/mL, P = 0.028). There was no significant difference in uric acid levels between the two groups. Multivariable logistic regression analysis showed that plasma XOR activity (odds ratio: 1.091 [95% confidence interval: 1.023-1.177] per 10 pmol/h/mL, P = 0.007) was an independent determinant of the risk for hypertension after adjustment for age, sex, current smoking and alcohol consumption, estimated glomerular filtration rate, brain natriuretic peptide, and insulin resistance index. The interaction of sex with plasma XOR activity was not significant for the risk of hypertension. In conclusion, plasma XOR activity is independently associated with hypertension in nondiabetic individuals who are not taking any medications.