Uric acid: from a biological advantage to a potential danger. A focus on cardiovascular effects

Molecular Basis of Cardiomyopathies in Type 2 Diabetes

Diabetic cardiomyopathy (DbCM) is a common complication in individuals with type 2 diabetes mellitus (T2DM), and its exact pathogenesis is still debated. It was hypothesized that chronic hyperglycemia and insulin resistance activate critical cellular pathways that are responsible for numerous functional and anatomical perturbations in the heart. Interstitial inflammation, oxidative stress, myocardial apoptosis, mitochondria dysfunction, defective cardiac metabolism, cardiac remodeling, hypertrophy and fibrosis with consequent impaired contractility are the most common mechanisms implicated. Epigenetic changes also have an emerging role in the regulation of these crucial pathways. The aim of this review was to highlight the increasing knowledge on the molecular mechanisms of DbCM and the new therapies targeting specific pathways.

Uric acid and cardiovascular diseases: a reappraisal

Serum uric acid (SUA) has garnered an increased interest in recent years as an important determinant of cardiovascular disease. Uric acid, a degradation product of purine metabolism, is affected by several inheritable and acquired factors, such as genetic mutation, metabolic syndrome, chronic kidney disease, and medication interactions. Even though elevated SUA have been commonly associated with the development of gout, it has significant impact in the development of hypertension, metabolic syndrome, and cardiovascular disease. Uric acid, in both crystalline and soluble forms, plays a key role in the induction of inflammatory cascade and development of atherosclerotic diseases. This concise reappraisal emphasizes key features about the complex and challenging role of uric acid in the development and progression of atherosclerosis and cardiovascular disease. It explores the pathogenesis and historical significance of uric acid, highlights the complex interplay between uric acid and components of metabolic syndrome, focuses on the pro-inflammatory and pro-atherogenic effects of uric acid, as well as discusses the role of urate lowering therapies in mitigating the risk of cardiovascular disease while providing the latest evidence to the healthcare professionals focusing on the clinical importance of SUA levels with regards to cardiovascular disease.

Establishment and validation of prediction model for atherosclerotic cardiovascular disease in patients with hyperuricemia

OBJECTIVE

To construct a risk prediction model for atherosclerotic cardiovascular disease (ASCVD) in patients with hyperuricemia.

METHODS

Data in this study were obtained from the National Health and Nutrition Examination Survey (NHANES) (2007-2010). Participants from Huashan Hospital were included as an external validation. Logistic regression analysis was used to explore the relevant factors of ASCVD in patients with hyperuricemia. The discriminability of the model was evaluated using the area under the curve (AUC) statistic of the receiver operating characteristic curve. Hosmer-Lemeshow test, correction curve and decision curve analysis (DCA) were used to evaluate the model.

RESULTS

A total of 389 patients collected from the NHANES were included in the final analysis. Logistic regression analysis showed that age, creatinine (Cr), glucose (Glu), serum uric acid (SUA), and history of gout were predictive factors for ASCVD in hyperuricemia (HUA) patients. These predictive factors were used to construct a nomogram. And 157 patients from NHANES were in the internal validation group and 136 patients from Huashan Hospital were in the external validation group. The AUC values of the three groups were 0.943, 0.735, and 0.664. The p values of the Hosmer-Lemeshow test were .568, .600, and .763. The calibration curve showed consistency between the nomogram and the actual observed values. The DCA curve indicated that the model has good clinical practicality.

CONCLUSION

This study constructed the ASCVD risk prediction model for HUA patients, which is beneficial for medical staff to detect high-risk populations of ASCVD in the early stage.

Robust positive association between serum urate and the risk of chronic obstructive pulmonary disease: hospital-based cohort and Mendelian randomisation study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and hyperuricaemia are both characterised by systemic inflammation. Preventing chronic diseases among the population with common metabolic abnormality is an effective strategy. However, the association of hyperuricaemia with the higher incidence and risk of COPD remains controversial. Therefore, replicated researches in populations with distinct characteristics or demographics are compellingly warranted.

METHODS

This cohort study adopted a design of ambispective hospital-based cohort. We used propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) to minimise the effects of potential confounding factors. A Cox regression model and restricted cubic spline (RCS) model were applied further to assess the effect of serum urate on the risk of developing COPD. Finally, we conducted a two-sample Mendelian randomisation (MR) analysis to explore evidence of causal association.

RESULTS

There is a higher incidence in the population with hyperuricaemia compared with the population with normal serum urate (22.29/1000 person-years vs 8.89/1000 person-years, p=0.009). This result is robust after performing PSM (p=0.013) and IPTW (p<0.001). The Cox model confirms that hyperuricaemia is associated with higher risk of developing COPD (adjusted HR=3.35 and 95% CI=1.61 to 6.96). Moreover, RCS shows that the risk of developing COPD rapidly increases with the concentration of serum urate when it is higher than the reference (420 µmol/L). Finally, in MR analysis, the inverse variance weighted method evidences that a significant causal effect of serum urate on COPD (OR=1.153, 95% CI=1.034 to 1.289) is likely to be true. The finding of MR is robust in the repeated analysis using different methods and sensitivity analysis.

CONCLUSIONS

Our study provides convincing evidence suggesting a robust positive association between serum urate and the risk of developing COPD, and indicates that the population with hyperuricaemia is at high risk of COPD in the Chinese population who seek medical advice or treatment in the hospital.

Association between uric acid and risk of venous thromboembolism in East Asian populations: a cohort and Mendelian randomization study

Background

Serum uric acid (SUA) levels have been associated with an increased risk and recurrence of venous thromboembolism (VTE) in European populations, but the potential causal relationship remains unclear. Large-scale studies on the association between SUA and VTE in East Asian populations are lacking, despite the high prevalence of hyperuricemia in this region. To address this, we conducted a cohort analysis and a two-sample Mendelian randomization (MR) study in East Asian populations.

Methods

We collected data on VTE patients from the China Pulmonary Thromboembolism Registry Study (CURES) and compared them to controls obtained from the China Health and Retirement Longitudinal Survey (CHARLS). Propensity score matching (PSM) and cubic-spline models were applied to assess the effect of SUA on VTE risk while adjusting for multiple covariates. We also performed two-sample MR analyses to infer potential causality based on summary statistics from Genome-wide Association Studies (GWAS) of SUA and VTE in the East Asian population.

Findings

We found that the SUA levels were higher in VTE patients (317.95 mmol/L) compared to the general population (295.75 mmol/L), and SUA ≥ 325 mmol/L was associated with an increased risk of VTE recurrence (P-value = 0.0001). The univariable MR suggested a causal relationship between elevated SUA and higher VTE risk (Pinverse variance weighted < 0.05), and multivariable MR showed that elevated SUA levels continued to promote the development of VTE after adjusting for multiple covariates (Pmultivariable residual < 0.05). Sensitivity analyses produced similar results for these estimations.

Interpretation

Our study provides evidence supporting a robust positive association between SUA and VTE in the East Asian population, and MR analyses suggest that this association is likely to be causal. Our findings underscore the importance of monitoring SUA levels in VTE prevention and call for urgent action to address the growing burden of hyperuricemia in the Asia-Pacific region.

Funding

This research was funded by Beijing Nova Program (No. Z211100002121057), National Natural Science Foundation of China (No. 82100065 and No. 62350004), CAMS Innovation Fund for Medical Sciences (No. 2021-I2M-1-061 and No. 2021-1-I2M-001), Elite Medical Professionals project of China-Japan Friendship Hospital (No. ZRJY2021-QM12), National Key Research and Development Project (No. 2021YFF1201200 and No. 2022YFC3341004).

Hyperuricaemia Does Not Interfere with Aortopathy in a Murine Model of Marfan Syndrome

Redox stress is involved in the aortic aneurysm pathogenesis in Marfan syndrome (MFS). We recently reported that allopurinol, a xanthine oxidoreductase inhibitor, blocked aortopathy in a MFS mouse model acting as an antioxidant without altering uric acid (UA) plasma levels. Hyperuricaemia is ambiguously associated with cardiovascular injuries as UA, having antioxidant or pro-oxidant properties depending on the concentration and accumulation site. We aimed to evaluate whether hyperuricaemia causes harm or relief in MFS aortopathy pathogenesis. Two-month-old male wild-type (WT) and MFS mice (Fbn1^C1041G/+) were injected intraperitoneally for several weeks with potassium oxonate (PO), an inhibitor of uricase (an enzyme that catabolises UA to allantoin). Plasma UA and allantoin levels were measured via several techniques, aortic root diameter and cardiac parameters by ultrasonography, aortic wall structure by histopathology, and pNRF2 and 3-NT levels by immunofluorescence. PO induced a significant increase in UA in blood plasma both in WT and MFS mice, reaching a peak at three and four months of age but decaying at six months. Hyperuricaemic MFS mice showed no change in the characteristic aortic aneurysm progression or aortic wall disarray evidenced by large elastic laminae ruptures. There were no changes in cardiac parameters or the redox stress-induced nuclear translocation of pNRF2 in the aortic tunica media. Altogether, the results suggest that hyperuricaemia interferes neither with aortopathy nor cardiopathy in MFS mice.

Association between periodontitis and uric acid levels in blood and oral fluids: a systematic review and meta-analysis

BACKGROUND

Uric acid, a formerly-known antioxidant that has recently been linked to numerous inflammatory diseases as a pro-inflammatory and -oxidative mediator in pathological conditions. It is imperative to reassess the association between periodontitis and uric acid locally and systematically. The aim of this systematic review was to systemically evaluate the association between periodontitis and the uric acid (UA) levels in blood, saliva and gingival crevicular fluid (GCF).

METHODS

Relevant clinical studies up to January 28, 2023 were identified and retrieved from electronic databases including PubMed, Scopus, EMBASE and Web of Science, with periodontitis, uric acid, hyperuricemia and gout as the keywords. The weighted (WMD) or standardized mean difference (SMD) was calculated using fixed- or random-effect models. Methodological heterogeneity was assessed.

RESULTS

Sixteen eligible observational studies and one RCT were enrolled, which included 1354 patients with periodontitis and 989 controls. Three sample types for UA detection were involved, including blood (n = 8), saliva (n = 9) and GCF (n = 1). Meta-analysis demonstrated an enhanced plasma UA concentration (WMD = 1.00 mg/dL, 95% CI 0.63 to 1.37, P < 0.001) but a decreased salivary UA level (SMD = -0.95, 95% CI -1.23 to -0.68, P < 0.001) in periodontitis versus control. Statistical heterogeneity among the plasma- and saliva-tested studies were moderate (I² = 58.3%, P = 0.066) and low (I² = 33.8%, P = 0.196), respectively.

CONCLUSIONS

Within the limitations of the enrolled studies, it seems that there is an association between periodontitis and increased blood UA and decreased salivary UA. (Registration no. CRD42020172535 in Prospero).

Association between serum uric acid levels of patients with gout and their complications and examination fees: A cross-sectional analysis

OBJECTIVE

Correlation influence factor analysis of gout patients' serum uric acid (SUA) levels, their examination fees, and various complications were explored.

METHODS

From January 2017 to December 2021, 17 666 patients with gout were obtained. Conduct quartile grouping according to gout patients' SUA levels was used to compare the differences between groups in terms of examination fees and complications. Kernel density estimation method was adopted to analyze the data distribution, Spearman and Mantel-Haenszel χ² tests were used to analyze the correlation between SUA levels and examination fees and complications. Binary logistic regression analysis was used to analyze the correlation influence factor between SUA levels and complications.

RESULTS

Of the 17 666 gout cases, 85.46% were male. Among them, 7637 (43.23%) were inpatients and 10 029 (56.77%) were outpatients. Compared with outpatients, age, SUA levels, and examination fees were significantly higher, and there were more complications among inpatients (P < 0.05). Correlation analysis revealed that outpatients and SUA levels of patients with gout were positively correlated with examination fees, cardiovascular diseases, pulmonary diseases, liver diseases, and kidney diseases (P < 0.01). Binary logistic regression analysis showed that SUA level is an independent influence factor for cardiovascular diseases, pulmonary diseases, liver diseases, and kidney diseases (odds ratio [95% confidence interval]: 1.002 [1.002-1.002], 1.001 [1.000-1.001], 1.003 [1.002-1.003], and 1.001 [1.001-1.002], respectively).

CONCLUSIONS

As SUA levels increased, examination fees, cardiovascular disease, pulmonary disease, liver disease, and kidney disease complications increased. SUA level is an independent influence factor for the combination of gout with cardiovascular diseases, pulmonary diseases, liver diseases, and kidney diseases.

Sex differences between serum uric acid levels and cardiovascular outcomes in patients with coronary artery disease after stent implantation

Background

The relationship between elevated serum uric acid (SUA) levels and cardiovascular outcomes after stent implantation remains uncertain. This study sought to evaluate the impact of SUA on 12-month cardiovascular outcomes after stent implantation.

Methods

We performed a retrospective study of patients who successfully underwent stent implantation and enrolled 3,222 patients with coronary artery disease (CAD) from a single center. SUA levels were measured before stent implantation. The patients were divided into six groups (<4, 4-4.9, 5-5.9, 6-6.9, 7-7.9 and ≥ 8 mg/dL) at SUA intervals of 1.0 mg/dL. The incidence of cardiovascular outcomes in the six groups was monitored for 1 year after stent implantation and the hazard ratios were estimated. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) for cardiovascular outcomes were estimated using a Cox proportional hazard regression analysis. The primary endpoint was all-cause death. The secondary endpoint was a composite of all-cause death, myocardial infarction, target vessel revascularization, stent thrombosis and stroke. The follow-up duration was 12 months.

Results

Over the 12-month follow-up period, there were 101 all-cause deaths and 218 MACCE. After adjustment for several parameters, the group with SUA levels of more than or equal to 8 mg/dL had significantly higher hazard ratios in the incidence of all-cause death or MACCE. The group with <4.0 mg/dL had significantly higher hazard ratios in all-cause death only in male patients. In contrast, there were no significant differences observed for cardiovascular outcomes in female patients.

Conclusions

Our study identified a U-shaped association between SUA levels and cardiovascular outcomes during 12-month follow-up for males, but not for females. Further studies are warranted to clarify the sex differences between SUA levels and clinical outcomes.

Sex Hormone-Binding Globulin (SHBG) Reduction: The Alarm Bell for the Risk of Non-Alcoholic Fatty Liver Disease in Adolescents with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) represents an endocrine condition affecting 5-18% of adolescents, frequently in association with obesity, metabolic alterations, and liver dysfunction. In this study, we aimed to evaluate the prevalence and risk factors for developing non-alcoholic fatty liver disease (NAFLD) in a cohort of PCOS adolescents. Thirty-two girls were assessed for anthropometric and biochemical markers: total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglycerides (TG), glucose, insulin, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma glutamyl transpeptidase (γGT). In addition, LH, FSH, 17β-Estradiol (E2), prolactin, testosterone (T), free testosterone, delta 4-androstenedione (D4 A), dehydroepiandrosterone sulfate (DHEAS) and sex hormone binding protein (SHBG) were also evaluated. All subjects underwent liver ultrasound to detect NAFLD. Our data demonstrated that PCOS adolescents complicated with NAFLD accounted for 37.5%, and those with obesity and lower SHBG were more predisposed to developing NAFLD. Moreover, SHBG showed a negative correlation with several parameters such as blood pressure, body mass index, waist circumference, insulin, and the homeostatic model assessment of insulin resistance (HOMA-IR). Our results demonstrated that the assessment of SHBG may allow the identification of PCOS adolescents at risk for developing NAFLD and metabolic alterations.

Allopurinol treatment reduced vascular remodeling and improved vascular functions in monocrotaline-induced pulmonary hypertensive rats

Increased oxidative stress and high uric acid are implicated in the pathogenesis of pulmonary hypertension (PH). This provides opportunity to benefit from drugs like allopurinol which suppresses both contributing factors. Therefore, we aimed to investigate the effects of allopurinol in preventing as well as reversing the pathological changes occurring in monocrotaline (MCT)-induced rat model of PH. Male rats were assigned into three groups based on the follow-up time: 7, 21 and 35 days. Time-matched controls of each group received single injections of MCT (60 mg/kg) intraperitoneally. Test groups consisted of rats who were treated with MCT on day 0 plus oral allopurinol (60 mg/kg) daily for 7 or 21 days. 35-day group received allopurinol for two weeks starting on the 22nd day following MCT injection. At the end of all-time points, rats were killed and basal pulmonary perfusion pressure, Fulton index, pulmonary arterial wall thickness and pulmonary arterial relaxations along with oxidative stress markers (MDA, SOD, XO), NO and uric acid levels were measured in all groups. MCT-injected rats had evidence of raised oxidative stress (high MDA and XO, low SOD levels) which was reversed by allopurinol co-treatment in all-time groups. Marked elevation of uric acid seen in 21- and 35 day-groups was also reversed by allopurinol. Reduced NO levels of 21 and 35 days were unchanged in allopurinol treated groups. Apart from an increase in arterial wall thickening which was maintained in all-time groups, no alterations in other cardiovascular parameters were observed in 7-day group. However, basal lung perfusion pressure and Fulton index significantly increased, while arterial relaxations decreased in 21- and 35-day groups. Co-treatment with allopurinol for 21 days improved these functional alterations, whereas late allopurinol treatment failed to affect them. Our results indicate that early treatment of MCT-induced PH with allopurinol ameliorated the impaired functional characteristics via suppressing the increased oxidative stress and uric acid, while treatment started after progression of the disease had no significant effect.

Uric Acid Expression in Carotid Atherosclerotic Plaque and Serum Uric Acid Are Associated With Cerebrovascular Events

BACKGROUND

Uric acid (UA) concentration within carotid plaque and its association with cerebrovascular events have not been detected or quantified. Systemically, serum UA is a marker of inflammation and risk factor for atherosclerosis. However, its association with carotid plaque instability and stroke pathogenesis remains unclear. In patients undergoing carotid endarterectomy, we aimed to determine whether UA is present differentially in symptomatic versus asymptomatic carotid plaques and whether serum UA is associated with cerebrovascular symptoms (stroke, transient ischemic attack, or amaurosis fugax).

METHODS

Carotid atherosclerotic plaques were collected during carotid endarterectomy. The presence of UA was assessed using Gomori methenamine silver staining as well as anti-UA immunohistochemical staining and its quantity measured using an enzymatic colorimetric assay. Clinical information was obtained through a retrospective review of data.

RESULTS

UA was more commonly detected in symptomatic (n=23) compared with asymptomatic (n=9) carotid plaques by Gomori methenamine silver (20 [86.9%] versus 2 [22.2%]; P=0.001) and anti-UA immunohistochemistry (16 [69.5%] versus 1 [11.1%]; P=0.004). UA concentration was higher in symptomatic rather than asymptomatic plaques (25.1 [9.5] versus 17.9 [3.8] µg/g; P=0.021). Before carotid endarterectomy, serum UA levels were higher in symptomatic (n=341) compared with asymptomatic (n=146) patients (5.9 [interquartile range, 4.6-6.9] mg/dL versus 5.2 [interquartile range, 4.6-6.2] mg/dL; P=0.009).

CONCLUSIONS

The current study supports a potential role of UA as a potential tissue participant and a systemic biomarker in the pathogenesis of carotid atherosclerosis. UA may provide a mechanistic explanation for plaque instability and subsequent ischemic cerebrovascular events.

The Cardiovascular Disease (CVD) Risk Continuum from Prenatal Life to Adulthood: A Literature Review

The risk of developing cardiovascular diseases (CVDs) arises from the interaction of prenatal factors; epigenetic regulation; neonatal factors; and factors that affect childhood and adolescence, such as early adiposity rebound (AR) and social and environmental influences. Thus, CVD risk varies between the group of low-risk metabolically healthy normal-weight subjects (MHNW); the intermediate-risk group, which includes metabolically healthy obese (MHO) and metabolically unhealthy normal-weight subjects (MUHNW); and the high-risk group of metabolically unhealthy obese (MUHO) subjects. In this continuum, several risk factors come into play and contribute to endothelial damage, vascular and myocardial remodeling, and atherosclerotic processes. These pathologies can occur both in prenatal life and in early childhood and contribute to significantly increasing CVD risk in young adults over time. Early intervention in the pediatric MUHO population to reduce the CVD risk during adulthood remains a challenge. In this review, we focus on CVD risk factors arising at different stages of life by performing a search of the recent literature. It is urgent to focus on preventive or early therapeutic strategies to stop this disturbing negative metabolic trend, which manifests as a continuum from prenatal life to adulthood.

Xanthine oxidoreductase: A leading actor in cardiovascular disease drama

Cardiovascular diseases (CVD) are the leading cause of global mortality and their pathogenesis lies mainly in the atherosclerotic process. There are close connections linking oxidative stress and inflammation to endothelial dysfunction, atherosclerosis and, consequently, to CVD. This review focuses on the role of xanthine oxidoreductase (XOR) and its products on the development of chronic inflammation and oxidative stress, responsible for atheromatous plaque formation. Evidence is reported that an excessive level of XOR products favors inflammatory response and plaque development, thereby promoting major cardiovascular risk factors. Also, the relationship between hyperuricemia and hypertension as well as between XOR activity and CVD is confirmed. In spite of the increasing number of clinical studies investigating the output of cardiovascular patients treated with urate-lowering therapies (including uricosuric drugs, XOR inhibitors and recombinant uricase) the results are still uncertain. The inhibition of XOR activity appears more promising than just the control of uricemia level in preventing cardiovascular events, possibly because it also reduces the intracellular accumulation of urate, as well as the production of reactive oxygen species. However, XOR inhibition also reduces the availability of the multifaced mediator nitric oxide and, at present, can be recommended only in hyperuricemic patients.

Correlation between serum uric acid levels and carotid plaque neovascularisation assessed by contrast-enhanced ultrasound

AIM

To investigate the potential impact of serum uric acid (SUA) levels on the grade of intraplaque neovascularisation (IPN) at contrast-enhanced ultrasound (CEUS).

MATERIAL AND METHODS

The study screened 212 patients with carotid atherosclerotic plaques using conventional ultrasound, and the patients then underwent CEUS. Based on the distribution of contrast medium microbubbles in the plaque, patients were split into three groups: 60 patients regarded as grade 0-1 (group A), 81 patients as grade 2 (group B), and 71 patients as grade 3 (group C), and SUA levels were measured on the second day after CEUS.

RESULTS

The frequencies of stroke were statistically different between the three groups (p<0.05). In grades 0, 1, 2, and 3, SUA levels ranged from 236.92 ± 72.75, 276.46 ± 67.31, 283.93 ± 53.85, and 384.49 ± 79.80 μmol/l, respectively. Spearman's analysis showed that the visual grade of IPN at CEUS correlated linearly with the SUA level (r=0.551, p<0.01). The difference in SUA levels between different sexes was statistically significant (p<0.05), and the differences in plaque echogenicity and diastolic blood pressure (DBP) between the three groups were also statistically significant (all p<0.05).

CONCLUSIONS

SUA levels correlate positively with the visual grade of IPN at CEUS, which may promote plaque vulnerability. The present results may further help to optimise therapy for vulnerable plaque and improve stroke risk stratification strategies.

The Impact of Uric Acid and Hyperuricemia on Cardiovascular and Renal Systems

The description of gout dates back almost 5000 years, and scientific interest in uric acid increased when it was found to be involved in the pathogenesis of gout. Since then, many basic and clinical studies have assessed the implications of uric acid for the oxidative system, inflammation, and cardiovascular and renal outcomes. Uric acid-lowering therapy failed to improve clinical hard outcomes in asymptomatic hyperuricemia, and it is retained in symptomatic hyperuricemia. Dietary and lifestyle modifications are critical to manage hyperuricemia. More studies are warranted to investigate the role of uric acid-lowering drugs on cardiovascular outcomes.

"Resurrected" human-source urate oxidase with high uricolytic activity and stability

As evidences showed that UOX(Gene ID: 391051), a single pseudogene formed after multiple mutations during human evolution, could be transcribed to mature mRNA and translated to two short peptides, we hypothesized that urate oxidase with higher homology with deduced human urate oxidase (dHU) might have lower immunogenicity. In this work, we constructed a "resurrected" human-source urate oxidase (rHU19) based on dHU. It obtained better uricolytic activity (8.29 U/mg) and catalytic efficiency (3.32 s^-1 μM^-1) compared with wild porcine urate oxidase (wPU) and FDA-approved porcine-baboon chimera (PBC). Maintaining high homology with dHU (93.75 %), rHU19 could be more suitable for the treatment of gout and hyperuricemia theoretically.

Impact of uric acid on liver injury and intestinal permeability following resuscitated hemorrhagic shock in rats

BACKGROUND

Multiorgan failure is a consequence of severe ischemia-reperfusion injury after traumatic hemorrhagic shock (HS), a major cause of mortality in trauma patients. Circulating uric acid (UA), released from cell lysis, is known to activate proinflammatory and proapoptotic pathways and has been associated with poor clinical outcomes among critically ill patients. Our group has recently shown a mediator role for UA in kidney and lung injury, but its role in liver and enteric damage after HS remains undefined. Therefore, the objective of this study was to evaluate the role of UA on liver and enteric injury after resuscitated HS.

METHODS

A murine model of resuscitated HS was treated during resuscitation with a recombinant uricase, a urate oxidase enzyme (rasburicase; Sanofi-Aventis, Canada Inc, Laval, Canada), to metabolize and reduce circulating UA. Biochemical analyses (liver enzymes, liver apoptotic, and inflammatory markers) were performed at 24 hours and 72 hours after HS. Physiological testing for enteric permeability and gut bacterial product translocation measurement (plasma endotoxin) were performed 72 hours after HS. In vitro, HT-29 cells were exposed to UA, and the expression of intercellular adhesion proteins (ZO-1, E-cadherin) was measured to evaluate the influence of UA on enteric permeability.

RESULTS

The addition of uricase to resuscitation significantly reduced circulating and liver UA levels after HS. It also prevented HS-induced hepatolysis and liver apoptotic/inflammatory mediators at 24 hours and 72 hours. Hemorrhagic shock-induced enteric hyperpermeability and endotoxemia were prevented with uricase.

CONCLUSIONS

After resuscitated HS, UA is an important mediator in liver and enteric injury. Uric acid represents a therapeutic target to minimize organ damage in polytrauma patients sustaining HS.

Flexible and disposable gold nanoparticles-N-doped carbon-modified electrochemical sensor for simultaneous detection of dopamine and uric acid

Catalytic and electrocatalytic applications of supported metal nanoparticles are hindered due to an aggregation of metal nanoparticles and catalytic leaching under harsh operations. Hence, stable and leaching free catalysts with high surface area are extremely desirable but also challenging. Here we report a gold nanoparticles-hosted mesoporous nitrogen doped carbon matrix, which is prepared using bovine serum albumin (BSA) through calcination. BSA plays three roles in this process as a reducing agent, capping agent and carbon precursor, hence the protocol exhibits economic and sustainable. Gold nanoparticles at N-doped BSA carbon (AuNPs@NBSAC)-modified three-electrode strip-based flexible sensor system has been developed, which displayed effective, sensitive and selective for simultaneous detection of uric acid (UA) and dopamine (DA). The AuNPs@NBSAC-modified sensor showed an excellent response toward DA with a linear response throughout the concentration range from 1 to 50 μM and a detection limit of 0.05 μM. It also exhibited an excellent response toward UA, with a wide detection range from 5 to 200 μM as well as a detection limit of 0.1 μM. The findings suggest that the AuNPs@NBSAC nanohybrid reveals promising applications and can be considered as potential electrode materials for development of electrochemical biosensors.

Paper Microfluidics and Tailored Gold Nanoparticles for Nonenzymatic, Colorimetric Multiplex Biomarker Detection

The plasmonic properties of gold nanoparticles (AuNPs) are a promising tool to develop sensing alternatives to traditional, enzyme-catalyzed reactions. The need for sensing alternatives, especially in underdeveloped areas of the world, has given rise to the application of nonenzymatic sensing approaches paired with cellulosic substrates to biochemical analysis. Herein, we present three individual, low-step, wet-chemistry, colorimetric assays for three target biomarkers, namely, glucose, uric acid, and free cholesterol, relevant in diabetes control and their translation into paper-based assays and microfluidic platforms for multiplexed analysis. For glucose determination, an in situ AuNPs synthesis approach was applied into the developed μPAD, giving semiquantitative measures in the physiologically relevant range. For uric acid and cholesterol determination, modified AuNPs were used to functionalize paper with a gold-on-paper approach with the optical properties changing based on different aggregation degrees and hydrophobic properties of particles dependent on analyte concentration. These paper-based assays show sensitivity ranges and limits of detection compatible for target analyte level determination and detection limits comparable to those of similar enzymatic, colorimetric systems, relying only on plasmonic transduction without the need for enzymatic activity or other chromogenic substrates. The resulting paper-based assays were integrated into a single 3D, multiplex paper-based device using paper microfluidics, showing the capability for performing different colorimetric assays with distinct requirements in terms of sample flow and sample uptake in test zones using a combination of both horizontal and vertical flows inside the same device. The presented device allows for multiparametric, colorimetric measures of different metabolite levels from a single complex sample matrix drop using digital color analysis, showing the potential for development of low-cost, low-complexity tools for diagnostics toward the point-of-care.

U-Shaped Association Between Serum Uric Acid and Short-Term Mortality in Patients With Infective Endocarditis

BACKGROUND

Increased uric acid (UA) levels have been reported to be associated with poor clinical outcomes in several conditions. However, the prognostic value of UA in patients with infective endocarditis (IE) is yet unknown.

METHODS

A total of 1,117 patients with IE were included and divided into two groups according to the current definition of hyperuricemia (UA>420 μmol/L in men and >360 μmol/L in women): hyperuricemia group (n=336) and normouricemia group (n=781). The association between the UA level and short-term outcomes were examined.

RESULTS

The in-hospital mortality was 6.2% (69/1117). Patients with hyperuricemia carried a higher risk of in-hospital death (9.8% vs. 4.6%, p=0.001). Hyperuricemia was not an independent risk factor for in-hospital death (adjusted odds ratio [aOR]=1.92, 95% confidence interval [CI]: 0.92-4.02, p=0.084). A U-shaped relationship was found between the UA level and in-hospital death (p<0.001). The in-hospital mortality was lower in patients with UA in the range 250-400 μmol/L. The aOR of in-hospital death in patients with UA>400 and <250 μmol/L was 3.48 (95% CI: 1.38-8.80, p=0.008) and 3.28 (95%CI: 1.27-8.51, p=0.015), respectively. Furthermore, UA>400 μmol/L (adjusted hazard ratio [aHR]=3.54, 95%CI: 1.77-7.07, p<0.001) and <250 μmol/L (aHR=2.23, 95%CI: 1.03-4.80, p=0.041) were independent risk factors for the 6-month mortality.

CONCLUSION

The previous definition of hyperuricemia was not suitable for risk assessment in patients with IE because of the U-shaped relationship between UA levels and in-hospital death. Low and high levels of UA were predictive of increased short-term mortality in IE patients.

Uric Acid in Metabolic and Cerebrovascular Disorders: A Review

BACKGROUND

Several studies showed a close link between metabolic syndrome (MetS), type 2 diabetes (T2DM) and cerebrovascular diseases. There is considerable debate regarding the role of uric acid (UA) as a risk factor in these conditions.

OBJECTIVE

The aim of this narrative review is to discuss the links between UA, MetS, T2DM and cerebrovascular disease.

METHODS

An extensive review has been conducted based on the scientific literature published in English, and indexed in MEDLINE (through PubMed), EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and Google Scholar from January to May 2019. Additional relevant studies published after the initial review were also considered during the period of June 2019-October 2019, during which, this manuscript was written. The Mesh Terms considered were: uric acid, antioxidant, oxidant, metabolic syndrome, diabetes, cerebrovascular diseases, stroke, haemorrhagic stroke, neurocognitive disorders, and their combinations.

RESULTS

The literature review shows a dose-dependent inflammatory action of UA, which occurs with serum concentrations >4 mg/dl (>0.24 mmol/l), representing one of the contributors to the chronic inflammatory process that underlies metabolic and cerebrovascular diseases.

CONCLUSION

UA, which is associated with arterial hypertension and cardiovascular diseases, represents one of the indicators of oxidative homeostasis. Increasing concentrations represent a status of active inflammation which is observed with metabolic and cerebrovascular diseases.

Detecting Rare Variants and Heteroplasmy of Mitochondrial DNA from High-Throughput Sequencing in Patients with Coronary Artery Disease

Background

Although mutations and dysfunction of mitochondrial DNA (mtDNA) are related to a variety of diseases, few studies have focused on the relationship between mtDNA and coronary artery disease (CAD), especially the relationship between rare variants and CAD.

Material/Methods

Two-stage high-throughput sequencing was performed to detect mtDNA variants or heteroplasmy and the relationship between them and CAD phenotypes. In the discovery stage, mtDNA was analyzed by high-throughput sequencing of long-range PCR products generated from the peripheral blood of 85 CAD patients and 80 demographically matched controls. In the validation stage, high-throughput sequencing for mtDNA target regions captured by GenCap Kit was performed on 100 CAD samples and 100 controls. Finally, tRNA fine mapping was performed between our study and the reported Chinese CAD study.

Results

Among the tRNA genes, we confirmed a highly conserved rare variant, A5592G, previously reported in the Chinese CAD study, and 2 novel rare mutations that reached Bonferroni’s correction significance in the combined analysis were found (P=7.39×10⁻⁴ for T5628C in tRNA^Ala and P=1.01×10⁻⁵ for T681C in 12S rRNA) in the CAD study. Both of them were predicted to be pathological, with T5628C disrupting an extremely conservative base-pairing at the AC stem of tRNA^Ala. Furthermore, we confirmed the controversial issue that the number of non-synonymous heteroplasmic sites per sample was significantly higher in CAD patients.

Conclusions

In conclusion, our study confirmed the contribution of rare variants in CAD and showed that CAD patients had more non-synonymous heterogeneity mutations, which may be helpful in identifying the genetic and molecular basis of CAD.

Glucose, Fructose, and Urate Transporters in the Choroid Plexus Epithelium

The choroid plexus plays a central role in the regulation of the microenvironment of the central nervous system by secreting the majority of the cerebrospinal fluid and controlling its composition, despite that it only represents approximately 1% of the total brain weight. In addition to a variety of transporter and channel proteins for solutes and water, the choroid plexus epithelial cells are equipped with glucose, fructose, and urate transporters that are used as energy sources or antioxidative neuroprotective substrates. This review focuses on the recent advances in the understanding of the transporters of the SLC2A and SLC5A families (GLUT1, SGLT2, GLUT5, GLUT8, and GLUT9), as well as on the urate-transporting URAT1 and BCRP/ABCG2, which are expressed in choroid plexus epithelial cells. The glucose, fructose, and urate transporters repertoire in the choroid plexus epithelium share similar features with the renal proximal tubular epithelium, although some of these transporters exhibit inversely polarized submembrane localization. Since choroid plexus epithelial cells have high energy demands for proper functioning, a decline in the expression and function of these transporters can contribute to the process of age-associated brain impairment and pathophysiology of neurodegenerative diseases.

Pro-Aging Effects of Xanthine Oxidoreductase Products

The senescence process is the result of a series of factors that start from the genetic constitution interacting with epigenetic modifications induced by endogenous and environmental causes and that lead to a progressive deterioration at the cellular and functional levels. One of the main causes of aging is oxidative stress deriving from the imbalance between the production of reactive oxygen (ROS) and nitrogen (RNS) species and their scavenging through antioxidants. Xanthine oxidoreductase (XOR) activities produce uric acid, as well as reactive oxygen and nitrogen species, which all may be relevant to such equilibrium. This review analyzes XOR activity through in vitro experiments, animal studies and clinical reports, which highlight the pro-aging effects of XOR products. However, XOR activity contributes to a regular level of ROS and RNS, which appears essential for the proper functioning of many physiological pathways. This discourages the use of therapies with XOR inhibitors, unless symptomatic hyperuricemia is present.

Characteristics of laboratory findings of COVID-19 patients with comorbid diabetes mellitus

AIMS

Coronavirus disease (COVID-19), also referred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is instigated by a novel coronavirus. The disease was initially reported in Wuhan, China, in December 2019. Diabetes is a risk factor associated with adverse outcomes. Herein, our objective was to investigate the characteristics of laboratory findings of type 2 diabetes mellitus (T2DM) patients infected with SARS-CoV-2.

METHODS

This was a retrospective study and included 80 T2DM patients of Jinling Hospital from 2010 to 2020, as well as 76 COVID-19 patients without T2DM and 55 COVID-19 patients with T2DM who were treated at Huoshen hill Hospital from February 11 to March 18, 2020. We then compared the differences in laboratory test results between the three groups.

RESULTS

The levels of lymphocytes, uric acid (UA), and globulin in the T2DM group were significantly higher. In contrast, C-reactive protein (CRP), creatinine, and lactic dehydrogenase (LDH)levels were lower than those in the COVID-19 (p < 0.05) and COVID-19 + T2DM groups (p < 0.05). No considerable difference was observed regarding the levels of alanine aminotransferase (ALT), white blood cell (WBC), aspartate aminotransferase (AST), globulin, and blood urea nitrogen (BUN) in the three groups (p > 0.05).

CONCLUSION

T2DM patients infected with SARS-CoV-2 showed decreased levels of body mass index (BMI), lymphocytes, UA, and albumin, and increased CRP levels. The decreased BMI, UA, and albumin levels may be associated with oxidative stress response and nutritional consumption. The decreased lymphocyte counts and increased CRP levels may be related to the infection.

Soluble uric acid induces myocardial damage through activating the NLRP3 inflammasome

Uric acid crystal is known to activate the NLRP3 inflammasome and to cause tissue damages, which can result in many diseases, such as gout, chronic renal injury and myocardial damage. Meanwhile, soluble uric acid (sUA), before forming crystals, is also related to these diseases. This study was carried out to investigate whether sUA could also activate NLRP3 inflammasome in cardiomyocytes and to analyse the mechanisms. The cardiomyocyte activity was monitored, along with the levels of mature IL-1β and caspase-1 from H9c2 cells following sUA stimulus. We found that sUA was able to activate NLRP3 inflammasome, which was responsible for H9c2 cell apoptosis induced by sUA. By elevating TLR6 levels and then activating NF-κB/p65 signal pathway, sUA promoted NLRP3, pro-caspase 1 and pro-IL-1β production and provided the first signal of NLRP3 inflammasome activation. Meanwhile, ROS production regulated by UCP2 levels also contributed to NLRP3 inflammasome assembly and subsequent caspase 1 activation and mature IL-1β secretion. In addition, the tlr6 knockdown rats suffering from hyperuricemia showed the lower level of IL-1β and an ameliorative cardiac function. These findings suggest that sUA activates NLRP3 inflammasome in cardiomyocytes and they may provide one therapeutic strategy for myocardial damage induced by sUA.

Analyzing the Association between Hyperuricemia and Periodontitis: A Cross-Sectional Study Using KoGES HEXA Data

Hyperuricemia arises from the buildup of excessive uric acid in the blood, and it is implicated in the development of periodontitis. The objective of this study was to investigate the association between hyperuricemia and periodontitis using a cross-sectional study design and Korean Genome and Epidemiology Study Health Examinee (KoGES HEXA) data. This prospective cohort study used epidemiological data from the KoGES from 2004 to 2016. Among 173,209 participants, 8809 with hyperuricemia and 126,465 controls (non-hyperuricemia) were selected. This study defined hyperuricemia as >7.0 mg/dL of uric acid in men and >6.0 mg/dL in women. This study analyzed the history of periodontitis among hyperuricemia and control participants. Participants’ age, gender, income, obesity, smoking, alcohol consumption, and nutritional intake were all examined. Chi-square tests, independent t-tests, and two-tailed analyses were used for statistical analysis. The adjusted OR (aOR) of hyperuricemia for periodontitis was 0.89 (95% confidence interval (CI) = 0.81–0.96, p = 0.005). This study demonstrated that hyperuricemia was associated with periodontitis. This finding meant that elevated uric acid levels could have a positive effect on periodontitis. However, further studies should be performed to determine the range of uric acid levels beneficial to periodontal health.

Uric acid and uric acid to creatinine ratio in the assessment of chronic obstructive pulmonary disease: Potential biomarkers in multicomponent models comprising IL-1beta

Chronic obstructive pulmonary disease (COPD) is a complex and heterogeneous disease, with oxidative stress and inflammation implicated in its development. Uric acid (UA) could exert anti-oxidative, pro-oxidative or pro-inflammatory effects, depending on the specific context. It was recently shown that soluble UA, and not just its crystals, could activate the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, leading to interleukin (IL)-1β secretion. We aimed to assess the differences in blood levels of UA and its ratio with creatinine (UCR) between COPD patients and healthy subjects, as well as their association with disease severity, smoking status, common COPD comorbidities and therapy regimes. The diagnostic characteristics of UA and UCR were also explored. This study included 109 stable COPD patients and 95 controls and measured white blood cells (WBC), C-reactive protein (CRP), fibrinogen (Fbg), IL-1β, creatinine (CREAT) and UA. All of the parameters were increased in COPD patients, except for CREAT. UA and UCR were positively associated with WBC, CRP and IL-1β. COPD smokers had lower UA and UCR values. Common COPD therapy did not affect UA or UCR, while patients with cardiovascular diseases (CVD) had higher UA, but not UCR, levels. Patients with higher UCR values showed worse disease-related outcomes (lung function, symptoms, quality of life, history of exacerbations, BODCAT and BODEx). Also, UCR differentiated patients with different severity of airflow limitation as well as symptoms and exacerbations. The great individual predictive potential of UCR and IL-1β was observed with their odds ratios (OR) being 2.09 and 5.53, respectively. Multiparameter models of UA and UCR that included IL-1β were able to correctly classify 86% and 90% of cases, respectively. We suggest that UA might be a useful biomarker when combined with IL-1β, while UCR might be even more informative and useful in overall COPD assessments.

Sex Differences in Association of Elevated Blood Pressure with Variables Characterizing Cardiometabolic Risk in Young Subjects with or Without Metabolic Abnormalities

Males present higher blood pressure (BP) values, higher prevalence of elevated BP, and a different prevalence of cardiometabolic risk factors when compared with females. We assumed that the trends of risk markers across BP categories (normotension, high normal BP, and hypertension) differ in young males and females, and between subjects without metabolic abnormalities (without obesity, insulin resistance, atherogenic dyslipidemia, hyperuricemia, or microinflammation) and those presenting them. Data from 2543 subjects (48% males) aged from 16 to 23 years were analyzed. The findings showed that 15% of males and 4% of females presented high normal BP while 9% and 1%, respectively, had hypertension. In males, variables characterizing obesity status, insulin sensitivity, atherogenic dyslipidemia, uric acid, adiponectin, a soluble receptor for advanced glycation end-products, and leukocyte counts showed worsening trends across BP categories. Females presented significant trends only for obesity measures, LDL-cholesterol, and non-HDL-cholesterol. Across BP categories, trends of variables characterizing cardiometabolic risk differed among abnormalities-free and presenting males. The multivariate model selected measures of central obesity, atherogenic dyslipidemia, insulin resistance, and uric acid as significant predictors of BP in both genders, and C-reactive protein in females. Sex differences in measures of cardiovascular health in juveniles may remain undiscovered unless two sexes are analyzed separately. These differences may have implications for sex-specific disease risk in adulthood.

Selected Atherosclerosis-Related Diseases May Differentially Affect the Relationship between Plasma Advanced Glycation End Products, Receptor sRAGE, and Uric Acid

Our study aimed to identify the relationship between advanced glycation end products (AGEs), soluble receptor for advanced glycation end products (sRAGE), the AGEs/sRAGE, and uric acid (UA) levels in selected atherosclerosis diseases, i.e., abdominal aortic aneurysms (AAA), aortoiliac occlusive disease (AIOD), and chronic kidney disease (CKD), resulting from apparent differences in oxidative stress intensity. Furthermore, we suggest that increased AGEs levels may stimulate an antioxidant defense system reflected by the UA level. The studied group size consisted of 70 AAA patients, 20 AIOD patients, 50 patients in the pre-dialyzed group (PRE), and 35 patients in the hemodialyzed group (HD). The enzyme-linked immunosorbent assay was used to measure AGEs and sRAGE levels. We found a significantly higher concentration of AGEs in CKD patients as compared to AAA and AIOD patients. Furthermore, the sRAGE level was higher in the CKD patients in comparison to AIOD and AAA patients. UA level was significantly higher in the PRE group compared to AAA patients. In conclusion, the diseases included in this study differ in the anti- and prooxidant defense system, which is reflected in the relations between the AGEs, the sRAGE, the AGEs/sRAGE ratio, as well as the UA levels.

Circulating leptin is associated with serum uric acid level and its tubular reabsorption in a sample of adult middle-aged men

PURPOSE

Leptin is associated with cardiovascular risk factors (e.g. hypertension, insulin resistance, kidney disease and excess body weight). Experimental studies showed that leptin might affect serum uric acid, by modulation of the uric acid excretion. However, there are few observational data on the relationship between leptin and uric acid in the general population. Therefore, the aim of the present study was to evaluate the relationship between leptin and uric acid and its excretion in a large middle-aged male general population.

METHODS

A sample of 930 adult male individuals (mean age: 52 years) without therapy for high uric acid was included in the analysis (the Olivetti Heart Study).

RESULTS

Uric acid was significantly and positively associated with blood pressure, BMI, waist circumference, insulin resistance, C-reactive protein and leptin (p < 0.01), while inversely with renal function (p = 0.01). The multivariate analysis confirmed the association between leptin and uric acid after adjustment for potential confounders (p < 0.01). After division for adiposity, this trend was confirmed separately for normal weight and excess body weight participants. Moreover, leptin was inversely associated with excretion of uric acid (p < 0.01), also in multivariate analysis (p = 0.03).

CONCLUSION

The results of this study indicate a positive association between circulating leptin levels and uric acid, independently of potential confounders, both in normal and excess body weight men. Furthermore, an inverse association between leptin and uric acid excretion was detected.

Hyperuricemia as a potential plausible risk factor for periodontitis

Elevated blood uric acid (UA) levels have been positively associated with the severity of periodontitis. It thus brings out a hypothesis that hyperuricemia, a pathological elevation of blood UA, might be a risk factor for periodontitis. Namely, periodontitis individuals with Hu might acquire more severe periodontal destruction compared to those without Hu. To support the hypothesis, four aspects of evidences are proposed. First, hyperuricemia and periodontitis share many metabolic and inflammatory comorbidities such as metabolic syndrome, diabetes and cardiovascular diseases which are commonly related to elevated UA levels and gout. Second, observational and interventional studies have found altered UA levels in blood and saliva in periodontitis patients or after periodontal treatment, suggesting an epidemiological connection between hyperuricemia and periodontitis. Third, plausible immuno-metabolic mechanisms by which hyperuricemia might promote the progression of periodontitis are suggested, such as impaired immune response, oxidative stress, pathological bone remodeling and dysbiosis. The last, our empirical data exhibited elevated UA levels in gingival tissue in periodontitis mice compared to controls. If the hypothesis is true, given the high prevalence of the two conditions, hyperuricemia would be a significant risk factor increasing the global burden of periodontal diseases. Evidences on a directional correlation between hyperuricemia and periodontitis are sparse. Longitudinal and experimental studies would be necessary to determine the magnitude of periodontal risk, if any, exacerbated by hyperuricemia and the underlying mechanisms.

A fast and facile electrochemical method for the simultaneous detection of epinephrine, uric acid and folic acid based on ZrO2/ZnO nanocomposites as sensing material

A novel electrochemical sensor based on ZrO₂ and ZnO hybrid nanocomposites was developed for simultaneous determination of epinephrine (EA), uric acid (UA) and folic acid (FA) with the highly selective and ultrasensitive. The nanocomposites have been synthesized by chemical precipitation and thermal calcine method with economical, eco-friendly and practical nature. Their structure and electrochemical properties were investigated by X-ray diffraction (XRD), X-ray photo electron spectroscopy (XPS), scanning electron microscopy (SEM) and electrochemical techniques. The results reveal that the ZrO₂/ZnO nanocomposites can possesses highly exposed catalytic sites, favorable conductivity, and the sensor excellent signal response for EP, UA and FA under the optimal condition. The electrochemical sensing platform has a low detection limit of 0.039 μM, 0.29 μM and 0.037 μM and a wide detection range of 0.8-420 μM, 10-2400 μM and 2-480 μM, respectively. It was also tested with a human blood serum sample at physiological pH with recovery 97.3-103.8% and relation standard deviation less than 5%. It indicates that the electrochemical sensors has a hopeful capacity of extensive applications in bioanalysis and diseases diagnosis.

Urine Glucose Excretion Attenuates the Association Between Lipid Accumulation Product and Serum Uric Acid in Subjects with Prediabetes

PURPOSE

Obesity is known to be strongly associated with hyperuricemia. Moreover, the impact of urine glucose excretion (UGE) on serum uric acid (UA) levels has gained much more attention in recent years. Yet concern is raised about whether UGE influences the relationship between obesity and hyperuricemia. The aim of this study was to assess the effect of UGE on the association between lipid accumulation product (LAP), a novel marker of visceral adipose accumulation, and UA in subjects with prediabetes.

MATERIALS AND METHODS

Data were obtained from a cross-sectional study. A total of 3645 subjects with prediabetes were included in the present study. The separate and joint associations of LAP and UGE with hyperuricemia were examined using logistic regression analyses.

RESULTS

LAP was positively associated with UA in both genders. Subgroup analysis based on UGE revealed that the association was strongest in subjects with low UGE (r = 0.328, p < 0.001), whereas the positive association was weakened, but still remained significant in subjects with moderate and high UGE. High LAP was significantly associated with an increased odds ratio for hyperuricemia after adjustment for potential confounders in the overall population (OR = 2.07, 95% CI: 1.66-2.58, p < 0.001). However, a downward trend in odds ratios for hyperuricemia was observed across UGE categories. In addition, the joint association analysis confirmed that the relationship between LAP and hyperuricemia was attenuated by UGE.

CONCLUSION

The positive association between LAP and UA appears to be attenuated by UGE, indicating that promoting UGE may be an effective strategy for controlling UA levels, especially for people with obesity who are at increased risk for hyperuricemia.

Correlation Between Serum Uric Acid Level and Central Body Fat Distribution in Patients with Type 2 Diabetes

BACKGROUND

The aim of this study was to investigate the correlation between serum uric acid level and central body fat distribution in patients with type 2 diabetes (T2DM).

METHODS

A total of 867 patients with T2DM were enrolled. Measurements of central fat distribution were obtained by dual energy X-ray absorptiometry. Patients were stratified into three groups according to their levels of serum uric acid (SUA). Multiple linear regression analysis was used to determine the association between SUA and central body fat distribution. Logistic regression analysis was used to estimate the risk factors for hyperuricemia (HUA). Mediation analysis was applied to assess the overall, direct, and indirect mediators of SUA levels.

RESULTS

Multiple linear regression analysis showed that SUA levels were significantly positively correlated with waist circumference (WC), body mass index (BMI), visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), Android fat mass, Gynoid fat mass, fasting c-peptide (F-CP), and area under the curve of C-peptide (P < 0.05 for all). VAT [odds ratio (OR), 2.367; 95% confidence interval (CI), 1.078-5.197; P < 0.001)], WC (OR, 1.041; 95% CI, 1.011-1.072; P < 0.001), high-density lipoprotein (OR, 0.274; 95% CI, 0.104-0.727; P < 0.001), and estimated glomerular filtration rate (OR, 0.966; 95% CI, 0.959-0.973; P < 0.001) were found to be independent risk factors for T2DM patients with HUA. After mediation analysis, BMI and central obesity were found to have different partial effects on the association between SUA and F-CP (P < 0.001).

CONCLUSION

In patients with T2DM, HUA was positively correlated with F-CP and central body fat distribution, especially VAT. These results suggest that central obesity may play a role in the positive correlation between HUA and insulin resistance (IR).

Asymptomatic Hyperuricemia Associates with Cardiometabolic Risk Indicators in Overweight/Obese but Not in Lean Adolescents

PURPOSE

In overweight/obese adolescents, asymptomatic hyperuricemia is associated with increased prevalence of metabolic syndrome, its components, and a higher cardiometabolic risk. Whether similar associations exist in lean hyperuricemic adolescents is unknown.

SUBJECTS AND METHODS

In 2424 adolescents (51.9% females) aged 16-19 years, anthropometric variables, blood pressure, uric acid, glucose, insulin, lipid profile, inflammatory markers, and renal function were determined. Continuous cardiometabolic score was calculated. Normouricemic vs hyperuricemic subjects were compared among lean and overweight/obese individuals of both sexes.

RESULTS

Females (5.4%) and males (13.3%) presented with hyperuricemia; among them 63% of females and 53% of males were lean. In both sexes, hyperuricemic lean and hyperuricemic overweight/obese adolescents displayed similar uric acid concentrations (eg, males: 455±30 vs 461±32 µmol/L, respectively, p=0.933). Lean normouricemic adolescents manifested significantly lower uric acid levels than their overweight/obese peers (eg, males: 333±46 vs 357±41 µmol/L, respectively, p<0.001). Lean normouricemic and hyperuricemic subjects presented similar cardiometabolic score (eg, males: 2.60±0.67 vs 2.64±0.60, respectively, p=0.998); among overweight/obese adolescents those with hyperuricemia displayed higher scores compared with their normouricemic counterparts (eg, males: 3.36±1.04 vs 4.21±1.65, respectively, p<0.001). A decision-tree model revealed phenotypes associated with higher uricemia, however, distribution of individuals with hyperuricemia among phenotypes was random.

CONCLUSION

In lean adolescents, hyperuricemia is not associated with cardiometabolic profile indicating an increased risk. Existence of this rather prevalent phenotype remains undetected unless lean and overweight/obese subjects are analyzed separately. Longitudinal studies are needed to elucidate the potential clinical consequences of asymptomatic hyperuricemia in lean subjects in later life.