Uric acid and neurological disease: a narrative review

Xanthine Oxidoreductase: A Double-Edged Sword in Neurological Diseases

Non-communicable neurological disorders are the second leading cause of death, and their burden continues to increase as the world population grows and ages. Oxidative stress and inflammation are crucially implicated in the triggering and progression of multiple sclerosis, Alzheimer's disease, amyotrophic lateral sclerosis, Huntington's disease, Parkinson's disease, and even stroke. In this narrative review, we examine the role of xanthine oxidoreductase (XOR) activities and products in all the above-cited neurological diseases. The redox imbalance responsible for oxidative stress could arise from excess reactive oxygen and nitrogen species resulting from the activities of XOR, as well as from the deficiency of its main product, uric acid (UA), which is the pivotal antioxidant system in the blood. In fact, with the exception of stroke, serum UA levels are inversely related to the onset and progression of these neurological disorders. The inverse correlation observed between the level of uricemia and the presence of neurological diseases suggests a neuroprotective role for UA. Oxidative stress and inflammation are also caused by ischemia and reperfusion, a condition in which XOR action has been recognized as a contributing factor to tissue damage. The findings reported in this review could be useful for addressing clinical decision-making and treatment optimization.

Association between the ratio of serum uric acid to high density lipoprotein cholesterol and depressive symptoms in middle-aged and elderly Chinese

BACKGROUND

Previous studies have reported that metabolic syndrome is associated with depression. In recent years, the ratio of uric acid to high-density lipoprotein cholesterol (UHR) has been considered as a new effective marker of metabolic syndrome. The purpose of this study was to investigate the association between UHR and depression in people aged 45 years and older in China using the China Health and Retirement Longitudinal Study(CHARLS) database.

METHODS

A total of 10,396 subjects aged 45 years and above were included in this cross-sectional study. The Center for Epidemiologic Studies Depression Scale (CESD-10) was used to facilitate rapid screening and assessment of depression. A CESD-10 score of ≥ 10 was considered the critical value of depression. UHR was calculated from the ratio of serum uric acid (mg/dL) to high-density lipoprotein cholesterol (mg/dL). Linear regression and logistic regression were used to explore the relationship between UHR and depression, respectively. In addition, subgroup analysis and interaction tests were performed.

RESULTS

The study found that UHR was negatively associated with depression. In the fully adjusted model, every 1-unit increase in UHR was associated with a 14% lower odds of developing depression (OR =  0.14, 95% CI: 0.05-0.37). Participants in the highest quartile of UHR were 24% less likely to develop depression compared with participants in the lowest quartile (OR =  0.76, 95% CI: 0.67-0.87). The interaction analysis indicates that this negative correlation is more pronounced in the subgroup aged 60 years and above.

CONCLUSION

UHR was significantly negatively correlated with depressive symptoms in the middle-aged and elderly Chinese population. However, further prospective studies are needed to accurately elucidate the causal relationship between increased UHR levels and the risk of depression. Therefore, larger cohort studies are needed to support these findings.

MWCNTs-Beta-Cyclodextrin-reduced graphene oxide gel based electrochemical sensor for simultaneous detection of dopamine and uric acid in human sweat samples

Accurate determination of dopamine (DA) and uric acid (UA) in biological samples is crucial in diagnosing neurodegenerative disorders and gout, respectively. Here we report a highly sensitive and inexpensive, flexible screen-printed sensor for determining DA and UA in sweat samples. Beta-cyclodextrin-based (βCD) composite gel with reduced graphene oxide (rGO) was synthesized by self-polymerization of βCD at an optimum ratio of "good" and "poor solvent". Multiwall carbon nanotubes (MWCNTs) were incorporated into the composite as a conductive filler. The MWCNTs-βCD-rGO gel provides selective biorecognition of DA and UA at the electrode surface through guest-host interaction. The gels were characterized by XRD, TGA, FTIR, UV-Vis, 1H NMR, FESEM, XPS and optical microscopy. The flexible printed sensor showed linear DA detection in the range 0.25 to 16 μM with a correlation coefficient (R2) of 0.9890, limit of detection (LoD) of 0.08 μM and sensitivity of 3.63 μA μM-1 cm-2. Similarly, UA calibration showed linear detection from 50 to 700 μM with a R2 value of 0.9860, LoD of 0.078 μM and sensitivity of 0.118 μA μM-1 cm-2. The SPE/MWCNTs-βCD-rGOsensor showed simultaneous determination of DA and UA from exercise induced sweat samples. The proposed sensor demonstrated excellent repeatability and satisfactory recoveries in human sweat.

Allopurinol use and risk of multiple sclerosis

BACKGROUND

Low uric acid levels have been observed in patients with multiple sclerosis (MS). As allopurinol is commonly used to lower uric acid in gout patients, this study examined allopurinol use in individuals with MS during the five years before diagnosis, compared to a matched control group.

METHODS

This nationwide case-control study used Danish health registry data. 9,063 individuals diagnosed with MS between 2008 and 2023 were included on the day of MS diagnosis, while 90,630 controls, were matched from the general population. Controls were matched on age, gender, place of residence, and inclusion date. Allopurinol prescriptions were tracked annually for five years prior to the inclusion date. The primary outcome was the odds ratio of allopurinol use in MS patients compared to controls, analyzed using conditional logistic regression.

RESULTS

In the five years prior to the MS diagnosis or matching date for controls, allopurinol use was consistently lower in MS cases. In total, 0.30% (n = 27) of MS cases had at least one allopurinol prescription, compared to 0.62% (n = 558) of controls, corresponding to an odds ratio of 0.48 (95% CI: 0.33-0.71).

CONCLUSIONS

Individuals diagnosed with MS had significantly lower allopurinol use in the five years preceding their diagnosis, suggesting an inverse relationship between uric acid levels and MS risk. Reduced uric acid levels may be associated with early MS development, possibly due to its antioxidant properties or metabolic changes. Alternatively, these findings suggest a possible protective effect of allopurinol against MS, warranting further investigation.

In situ fabricated gold nanostars on hydrogel beads as photo-oxidase mimics for rapid and sustainable POCT of uric acid

Synthetic enzyme mimics surpass their natural counterparts in terms of stability, efficiency, and cost-effectiveness, making them highly valuable for catalytic applications. Gold nanomaterials, particularly gold nanostars, have emerged as promising enzyme mimetic nanocatalysts due to their enhanced light interaction and superior catalytic efficiency. In this study, gold nanostars grown in situ on the surface of core-shell hydrogel beads exhibited specific oxidase-like activity when exposed to light. Photoexcitation of gold nanostars generates singlet oxygen through the interaction of positive holes and superoxide radicals, resulting in photo-oxidase-like activity. Attaching the gold nanostars to the hydrogel bead surface prevented catalytic activity loss caused by agglomeration, resulting in a marked improvement in catalytic stability. This stability is evident from the sustained catalytic activity of the hydrogel bead-embedded gold nanostars, even after 60 days of prolonged incubation in an aqueous medium, and their strong catalytic performance across multiple reaction cycles. Leveraging this photo-oxidase-like activity, a point-of-care testing (POCT) setup is developed for highly sensitive uric acid detection. The system achieved a remarkable detection limit of 0.9 μM and demonstrated excellent accuracy in blood serum and urine sample analyses. Furthermore, the integration of smartphone technology facilitated rapid and convenient on-site testing, bridging the gap between laboratory settings and real-world applications. This approach offers a practical and sustainable solution for efficient and accurate uric acid monitoring in diverse settings.

Targeting uric acid: a promising intervention against oxidative stress and neuroinflammation in neurodegenerative diseases

Oxidative stress and neuroinflammation are recognized as key factors in the development of neurodegenerative diseases, yet effective interventions and biomarkers to address oxidative stress and neuroinflammation in these conditions are limited. Uric acid (UA), traditionally associated with gout, is now gaining prominence as a potential target in neurodegenerative diseases. Soluble UA stands out as one of the most vital antioxidant compounds produced by the human body, accounting for up to 55% of the extracellular capacity to neutralize free radicals. While there is increasing evidence supporting the neuroprotective properties of UA in Parkinson's disease and Alzheimer's disease, gaps in knowledge still exist regarding the underlying mechanisms and how to effectively translate these benefits into clinical practice. Moreover, the current UA elevation therapy exhibits unstable antioxidant properties, individual variability, and even adverse effects, limiting its potential clinical applications. This review consolidates recent advancements in understanding how UA exerts neuroprotective effects on neurodegenerative diseases and emphasizes the dual roles of UA in managing oxidative stress and neuroinflammation. Additionally, the review elucidates the mechanisms through which UA confers neuroprotection. Based on this, the review underscores the significance of UA as a potential biomarker and aims to provide a comprehensive understanding of its potential as a therapeutic target, while also addressing possible challenges to clinical implementation.

The impact of uric acid levels in the pathophysiology and its contribution to the prediction of diagnosis in restless legs syndrome

Restless legs syndrome (RLS) is characterized by an uncomfortable urge to move the legs, worsened in the evening, occurring at rest, and relieved temporarily by movement. Although its pathophysiology remains incompletely understood, oxidative stress has been suggested. Uric acid (UA) is a marker associated with oxidative stress, and its reduced levels pose a risk for certain neurodegenerative diseases. In this study, we aimed to assess serum UA concentrations in RLS patients to gain insights into its role in the etiopathogenesis of the condition.: This study involved 200 individuals. Serum UA levels were compared with clinical parameters. Disease severity was assessed, categorizing patients into "mild," "moderate," "severe," and "very severe" subgroups. Comparative analysis of UA levels was conducted between these subgroups and the control group. Patients exhibited a statistically significant reduction in UA levels compared to controls (p = 0.001; p < 0.01). No significant disparities in UA levels were observed among patients based on RLS scores (p > 0.05). The generalized linear model in which UA serves as the dependent variable revealed statistically significant associations with the "moderate" and "severe" stages of RLS, as well as age (p < 0.05). Additionally, a ROC curve analysis was executed to evaluate the potential of UA as a biomarker. The ROC analysis, focusing on the patient-control classification, revealed a statistically significant area under the curve (AUC = 0.848, p < 0.001). Our study supports the hypothesis implicating serum UA levels in RLS pathogenesis. Further understanding of UA and its physiological effects will clarify on its role in RLS pathophysiology.

Rational design of Ag-doped MnFe2O4/HNTs for peroxidase-mimicking activity and colorimetric sensing of uric acid in human serum

Mimicking enzyme have significantly advanced sensing assays by replicating native enzyme functions, yet achieving both high catalytic activity and easy recyclability remains a challenge. In this study, Ag-doped MnFe2O4/halloysite nanotubes (HNTs) were rationally designed as a novel nanozyme by depositing in-situ Ag and MnFe2O4 nanoparticles onto HNTs. The resulting nanocomposite exhibited excellent peroxidase-like activity along with magnetic properties. Leveraging these features, a highly efficient and sensitive colorimetric system for detecting uric acid (UA) was developed. The Ag-doped MnFe2O4/HNTs catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine in the presence of H2O2, causing a color change from colorless to blue. The system showed a linear absorbance response to UA concentrations ranging from 1 to 20 μM, with a detection limit of 59 nM. Mechanistic studies revealed that reactive oxygen species intermediates (1O2) were generated through the decomposition of H2O2, leading to peroxidase-like activity in the Ag-doped MnFe2O4/HNTs. The assay was successfully applied to detect UA in human serum with recoveries over 99.68 %. This study indicates the successful application of Ag-doped MnFe2O4/HNTs for colorimetric UA detection in human serum. This research introduces a novel approach for designing recyclable, high-performance mimicking enzyme and establishes an effective colorimetric sensing platform for UA detection in human serum.

Uric Acid: A Biomarker and Pathogenic Factor of Affective Disorders and Neurodegenerative Diseases

Uric acid (UA), the end-product of purine metabolism, has a complicated physiological role in the body, showing the combination of regulating inflammatory response, promoting oxidation/anti-oxidation, and modifying autophagy activity in vivo. Meanwhile, various research and theories support that inflammation, oxidative stress, and other risk factors promote the onset and progression of affective disorders and neurodegenerative diseases. Existing studies suggest that UA may be involved in the pathophysiological processes of affective disorders in various ways, and there has been a gradual advance in the understanding of the interplay between UA levels and affective disorders and neurodegenerative diseases. This review summarized the role of UA in the process of inflammation, oxidative stress, and autophagy. On this basis, we discussed the correlation between UA and affective disorders and several neurodegenerative diseases, and simultaneously analyzed the possible mechanism of its influence on affective disorders and neurodegenerative diseases, to provide a theoretical basis for UA as a biomarker or therapeutic target for the diagnosis of these diseases.

Changes in serum uric acid, glutathione, and amyloid-β1-42 levels in Parkinson's disease patients and their association with disease progression and cognitive decline

OBJECTIVE

This study aims to evaluate the diagnostic significance of serum uric acid (UA), glutathione (GSH), and amyloid-β1-42 (Aβ1-42) levels in relation to disease progression and cognitive impairment in patients with Parkinson's disease (PD).

METHODS

A total of 209 PD patients with disease duration ranging from 4.0 to 6.8 years were enrolled. Based on the Hoehn-Yahr staging system, patients were classified into Early (n = 67), Medium-term (n = 70), and Advanced (n = 72) stages. Cognitive function was assessed using the Mini-Mental State Examination (MMSE), dividing the cohort into CD (cognitive dysfunction, n = 94) and NO-CD (no cognitive dysfunction, n = 115) groups. Serum UA, GSH, and Aβ1-42 levels were analyzed for correlations with clinical data. Independent risk factors and diagnostic value were determined through multivariable logistic regression models and receiver operating characteristic curve analysis.

RESULTS

Serum UA and GSH levels progressively declined with advancing disease stage, while Aβ1-42 increased. Compared to the NO-CD group, the CD group showed lower serum UA and GSH levels, and higher Aβ1-42 levels. Serum UA and GSH were inversely correlated with disease duration, levodopa equivalent daily dose, and Unified Parkinson's Disease Rating Scale scores, while Aβ1-42 showed positive correlations. UA (p = 0.006), GSH (p < 0.001), and Aβ1-42 (p = 0.040) were independent predictors of disease stage. Similarly, UA (p = 0.003), GSH (p < 0.001), and Aβ1-42 (p < 0.001) were independent predictors of cognitive dysfunction. The combined assessment of these markers demonstrated a higher area under the curve (AUC) than individual markers for disease and cognitive decline identification.

CONCLUSIONS

Serum UA, GSH, and Aβ1-42 are independent predictors of disease progression and cognitive decline in PD patients. Their combined use offers enhanced diagnostic accuracy for disease staging and cognitive impairment in PD.

Causal relationship between uric acid and stroke: a two-sample mendelian randomization study

Many previous observational studies have disputed whether there is a link between uric acid and stroke. And the causal relationship between uric acid and stroke is unclear. To determine whether there is a causal relationship between uric acid and stroke by using mendelian randomization (MR). Uric acid dataset was obtained from Anna Kottgen et al, with a sample size of 110,347 people, including 2450,548 single nucleotide polymorphisms (SNPs). Stroke pooled data from Malik R et al, publicly available in MEGASTROKE genome-wide association study, included meta-analysis data from 40,585 stroke patients and 406,111 control patients, totaling 8211,693 SNPs. The summary data of genome-wide association study of uric acid and stroke were collected from publicly available online databases. Inverse variance weighting was used to determine the causal relationship between uric acid and stroke. MR-Egger and weighted median model were used for supplementary analysis. Results were then analyzed for heterogeneity, pleiotropy, and sensitivity to ensure no statistical pleiotropy and to reduce bias. A total of 27 SNPs were included in this study after the disequilibrium instrumental variables were excluded. Check the PhenoScanner database for SNPs associated with confounders. In the end, a total of 8 SNPs were excluded. Two SNPs were excluded because the correction direction was the same. Since the F statistic is >10, rs10761587 and rs1825043 are excluded. Finally, 15 SNPs were selected as uric acid instrumental variables. Inverse variance weighting-fixed effect model suggested that there was no causal relationship between uric acid and stroke (odds ratio = 1.004, 95% confidence interval = 0.940, 1.072). MR-Egger and weighted median model also showed the same result. In addition, the results of this study were robust without heterogeneity and pleiotropy. This MR study suggests no support of a causal relationship between uric acid and stroke.

Association between uric acid and the risk of depressive symptoms in US adults: results from NHANES 2005-2018

BACKGROUND

This study explores the relationship between serum uric acid(UA) levels and depression. UA is the final product of purine metabolism in the human body, possessing certain physiological functions such as blood pressure regulation, antioxidation, DNA protection, and anti-aging, thereby drawing attention for its potential role in preventing and treating depression.

METHODS

This cross-sectional study includes 32,424 participants aged ≥ 20 years from the National Health and Nutrition Examination Survey (NHANES) conducted between 2005 and 2018, generating a nationally representative database. Depressive symptoms were assessed using the Patient Health Questionnaire-9. Serum uric acid concentration was measured using the uricase-peroxidase coupled method, and participants were divided into quartiles of serum uric acid concentration. Weighted data were calculated according to analysis guidelines. The association between serum uric acid and depressive symptoms was analyzed using weighted multivariable logistic regression models and restricted cubic spline regression analyses. Subgroup analyses were also performed.

RESULTS

Among 32,424 participants, 3,421 were defined as having depressive symptoms. The crude prevalence of depressive symptoms was 10.5% (weighted prevalence: 9.086% [95% confidence interval: 9.032-9.139%]). Compared with the first quartile, individuals with higher UA levels had a decreased risk of depressive symptoms by 9% (OR: 0.910, 95% CI: 0.797-10.40), 14.6% (OR: 0.854, 95% CI: 0.741-0.983), and 20.5% (OR: 7795, 95% CI: 0.680-0.930), respectively. Further restricted cubic spline regression analysis revealed a nonlinear association between UA and depressive symptoms, with an inflection point of 319.72 µmol/L. Subgroup multivariable weighted logistic regression analysis found that the association between UA and the risk of depressive symptoms remained consistent across all subgroups, demonstrating high stability and reliability.

CONCLUSION

This study emphasizes a significant nonlinear negative correlation between serum uric acid and depressive symptoms. This suggests that proper control of serum uric acid levels may play a role in preventing and treating depression.

Salivary uric acid dynamics are associated with stress response hormones among African Americans in an urban sample

Acute physiological responses to psychosocial stressors are a potential pathway underlying racial disparities in stress-related illnesses. Uric acid (UA) is a potent antioxidant that has been linked to disparities in stress-related illnesses, and recent research has shown that UA is responsive to acute social stress. However, an examination of the relationships between the purinergic system and other commonly measured stress systems is lacking. Here, we measure and characterize associations of salivary uric acid (sUA) with markers of hypothalamic-pituitary-adrenal (HPA) axis activation, sympathetic-adreno-medullar (SAM) axis activation, and acute inflammation. A community sample of 103 African Americans (33 male, 70 female) completed the Trier Social Stress Test to induce social-evaluative threat. Passive drool collected before, during, and after the stressor task provided salivary reactivity measures of UA (sUA), cortisol, dehydroepiandrosterone sulfate (DHEAS), salivary alpha amylase (sAA - a surrogate marker of SAM activity) and C-reactive protein (sCRP). Multiple regressions revealed that total activation of cortisol, DHEAS, and sCRP were each positively associated with higher total activation of sUA. Additionally, DHEAS reactivity was positively associated with sUA reactivity. Relationships between HPA-axis markers and sUA were especially observed among younger and male participants. Overall, findings suggest potential coordination of stress systems with sUA in response to acute stress, which may further the contributions of biological stress processes to racial health disparities.

Significance and amplification methods of the purine salvage pathway in human brain cells

Previous studies suggest that uric acid or reactive oxygen species, products of xanthine oxidoreductase (XOR), may associate with neurodegenerative diseases. However, neither relationship has ever been firmly established. Here, we analyzed human brain samples, obtained under protocols approved by research ethics committees, and found no expression of XOR and only low levels of uric acid in various regions of the brain. In the absence of XOR, hypoxanthine will be preserved and available for incorporation into the purine salvage pathway. To clarify the importance of salvage in the brain, we tested using human-induced pluripotent stem cell-derived neuronal cells. Stable isotope analyses showed that the purine salvage pathway was more effective for ATP synthesis than purine de novo synthesis. Blood uric acid levels were related to the intracellular adenylate pool (ATP + ADP + AMP), and reduced levels of this pool result in lower uric acid levels. XOR inhibitors are related to extracellular hypoxanthine levels available for uptake into the purine salvage pathway by inhibiting the oxidation of hypoxanthine to xanthine and uric acid in various organs where XOR is present and can prevent further decreases in the intracellular adenylate pool under stress. Furthermore, adding precursors of the pentose phosphate pathway enhanced hypoxanthine uptake, indicating that purine salvage is activated by phosphoribosyl pyrophosphate replenishment. These findings resolve previous contradictions regarding XOR products and provide new insights into clinical studies. It is suggested that therapeutic strategies maximizing maintenance of intracellular adenylate levels may effectively treat pathological conditions associated with ischemia and energy depletion.

Exploring the causal association between uric acid and lung cancer in east Asian and European populations: a mendelian randomization study

BACKGROUND

Lung cancer still ranks first in the mortality rate of cancer. Uric acid is a product of purine metabolism in humans. Its presence in the serum is controversial; some say that its high levels have a protective effect against tumors, others say the opposite, that is, high levels increase the risk of cancer. Therefore, the aim of this study was to investigate the potential causal association between serum uric acid levels and lung cancer.

METHODS

Mendelian randomization was used to achieve our aim. Sensitivity analyses was performed to validate the reliability of the results, followed by reverse Mendelian analyses to determine a potential reverse causal association.

RESULTS

A significant causal association was found between serum uric acid levels and lung cancer in East Asian and European populations. Further sublayer analysis revealed a significant causal association between uric acid and small cell lung cancer, while no potential association was observed between uric acid and non-small cell lung cancer, squamous lung cancer, and lung adenocarcinoma. The sensitivity analyses confirmed the reliability of the results. Reverse Mendelian analysis showed no reverse causal association between uric acid and lung cancer.

CONCLUSIONS

The results of this study suggested that serum uric acid levels were negatively associated with lung cancer, with uric acid being a potential protective factor for lung cancer. In addition, uric acid level monitoring was simple and inexpensive. Therefore, it might be used as a biomarker for lung cancer, promoting its wide use clinical practice.

Sex difference in the associations among hyperuricemia with self-reported peptic ulcer disease in a large Taiwanese population study

Background

Hyperuricemia may play a role in various systemic diseases. However, few studies have investigated the relationship between hyperuricemia and the risk of peptic ulcer disease (PUD). Therefore, in this population-based study, we enrolled over 120,000 participants from the Taiwan Biobank (TWB) and examined the risk factors for self-reported PUD. In addition, we investigated sex differences in the association between hyperuricemia and self-reported PUD.

Methods

Data of 121,583 participants were obtained from the TWB. Male participants with a serum uric acid level >7 mg/dl and female participants with a serum uric acid level >6 mg/dl were classified as having hyperuricemia. Details of self-reported PUD were obtained by questionnaire. The association between hyperuricemia and self-reported PUD in the male and female participants was examined using multivariable logistic regression analysis.

Results

The overall prevalence of self-reported PUD was 14.6%, with a higher incidence in males (16.5%) compared to females (13.5%). After multivariable adjustment, male sex [vs. female sex; odds ratio (OR) = 1.139; 95% confidence interval (CI) = 1.084-1.198; p < 0.001], and hyperuricemia (OR = 0.919; 95% CI = 0.879-0.961; p < 0.001) were significantly associated with self-reported PUD. Further, a significant interaction was found between sex and hyperuricemia on self-reported PUD (p = 0.004). Hyperuricemia was associated with a low risk of self-reported PUD in males (OR = 0.890; 95% CI = 0.837-0.947; p < 0.001) but not in females (p = 0.139).

Conclusion

The prevalence of self-reported PUD was higher in the male participants than in the female participants. Hyperuricemia was associated with low prevalence of self-reported PUD in males, but not in females. Further studies are needed to clarify the mechanisms behind these observations and verify the potential protective role of hyperuricemia on the development of self-reported PUD.

Association between pre-diagnostic serum uric acid levels in patients with newly diagnosed epilepsy and conversion rate to drug-resistant epilepsy within 5 years: A common data model analysis

PURPOSE

Drug-resistant epilepsy (DRE) poses a significant challenge in epilepsy management, and reliable biomarkers for identifying patients at risk of DRE are lacking. This study aimed to investigate the association between serum uric acid (UA) levels and the conversion rate to DRE.

METHODS

A retrospective cohort study was conducted using a common data model database. The study included patients newly diagnosed with epilepsy, with prediagnostic serum UA levels within a six-month window. Patients were categorized into hyperUA (≥7.0 mg/dL), normoUA (<7.0 and >2.0 mg/dL), and hypoUA (≤2.0 mg/dL) groups based on their prediagnostic UA levels. The outcome was the conversion rate to DRE within five years of epilepsy diagnosis.

RESULTS

The study included 5,672 patients with epilepsy and overall conversion rate to DRE was 19.4%. The hyperUA group had a lower DRE conversion rate compared to the normoUA group (HR: 0.81 [95% CI: 0.69-0.96]), while the hypoUA group had a higher conversion rate (HR: 1.88 [95% CI: 1.38-2.55]).

CONCLUSIONS

Serum UA levels have the potential to serve as a biomarker for identifying patients at risk of DRE, indicating a potential avenue for novel therapeutic strategies aimed at preventing DRE conversion.

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

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

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.