Uric acid and hypertension: a focused review and practical recommendations

Association of serum uric acid levels with blood pressure and the incidence of hypertension in the middle-aged and elderly populations

OBJECTIVE

This study aimed to investigate the relationship between serum uric acid (SUA) levels and hypertension in the middle-aged and elderly populations.

METHODS

The cross-sectional analysis included 13 349 middle-aged and elderly general health checkup examinees without cardiovascular disease. The retrospective cohort analysis included 6659 normotensive participants (mean age: 64.6 years). Participants were divided into three groups based on their SBP/DBP levels: normal (<120/<80 mmHg), high normal (120-129/<80 mmHg), and elevated (130-139/80-89 mmHg), and were classified into three groups based on the results of 75 g oral glucose tolerance test: normoglycemia, prediabetes, and diabetes.

RESULTS

SUA levels were significantly associated with SBP and DBP in this cross-sectional study. Over a mean 6.5-year follow-up period, 2038 participants developed hypertension. According to the SUA quartiles, the incidence of hypertension increased [26.1% in quartile (Q1) (≤4.1 mg/dl), 28.6% in Q2 (4.2-4.9 mg/dl), 32.6% in Q3 (5.0-5.8 mg/dl), 34.9% in Q4 (≥5.9 mg/dl); P for trend <0.001]. In multivariable analyses, SUA levels were positively associated with hypertension incidence only in the normal BP group [Q4 vs. Q1 odds ratio (OR): 1.64, 95% confidence intervals (CIs): 1.11-2.44; Q3 vs. Q1 OR: 1.69, 95% CI: 1.19-2.42] and in the normoglycemic group (Q4 vs. Q1 OR: 1.34, 95% CI: 1.02-1.76; Q3 vs. Q1 OR: 1.36, 95% CI: 1.07-1.74).

CONCLUSION

In the middle-aged and elderly populations, normotensive or normoglycemic individuals with SUA levels at least 5 mg/dl may be potential targets for SUA management to prevent hypertension.

Poor serum uric acid control increases risk for developing hypertension: a retrospective cohort study in China

Background

Serum uric acid (SUA) has been suggested as a contributor of hypertension. However, reports on the relationship between changes in SUA and hypertension are limited. Hence, we aimed to investigate the potential impact of SUA, especially its change over time, on hypertension incidence.

Methods

This dynamic cohort included 6052 participants without hypertension at baseline. Participants were categorized into six grades based on whether baseline SUA was high and whether changes in SUA progressed to hyperuricemia or decreased to normal levels. Grades 1 to 6 represented the participants' SUA control from best to worst. Logistic regression and restricted cubic spline (RCS) models were used to explore the association of the grades of SUA control and hypertension incidence.

Results

During a median follow-up of 6 years, 2550 (42.1%) participants developed hypertension. After adjusting confounding factors, compared to grade 1 with the best control of SUA, the odds ratios for grades 2 to 6 with worse control were 1.347 (1.109-1.636), 1.138 (0.764-1.693), 1.552 (1.245-1.934), 1.765 (1.170-2.663), and 2.165 (1.566-2.993), respectively. RCS indicated a linear correlation between the risk of hypertension and changes in SUA, and an elevated risk in participants with baseline hyperuricemia. Subgroup analyses showed that grades of SUA control had an interaction with systolic (P = 0.003) and diastolic blood pressure (P < 0.001). Sensitivity analyses further determined the robustness of the result that participants with poor SUA control have a higher risk of developing hypertension.

Conclusion

Poor SUA control, an increase in SUA over time, rises the risk of developing hypertension regardless of whether the initial SUA is normal or not. Initial hyperuricemia will exacerbate this risk. Effective SUA control should be an important measure for primary prevention of hypertension.

Serum uric acid: a futile bystander in endothelial function?

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Agents for the Treatment of Gout: Current Advances and Future Perspectives

Gout is characterized by hyperuricemia and the deposition of monosodium urate (MSU) crystals around joints. Despite the availability of several drugs on the market, its treatment remains challenging owing to the notable side effects, such as hepatorenal toxicity and cardiovascular complications, that are associated with most existing agents. This perspective aims to summarize the current research progress in the development of antigout agents, particularly focusing on xanthine oxidase (XO) and urate anion transporter 1 (URAT1) inhibitors from a medicinal chemistry viewpoint and their preliminary structure-activity relationships (SARs). This perspective provides valuable insights and theoretical guidance to medicinal chemists for the discovery of antigout agents with novel chemical structures, better efficiency, and lower toxicity.

Relationship between serum uric acid and hypertension in the general US population aged 20 years and older: A cross-sectional study based on NHANES 2007 to 2016

The aim of this study was to investigate the association between serum uric acid (UA) levels and hypertension in American individuals 20 years of age and older. We used continuous cross-sectional surveys from the National Health and Nutrition Examination Survey in the United States from 2007 to 2016. Our selected population was adults aged 20 years and older in the United States. We examined the association between serum UA and risk of hypertension using weighted univariate logistic regression analysis, weighted multivariate logistic regression analysis, weighted subgroup analysis, and weighted restricted cubic spline analysis. Serum UA was significantly linked with hypertension in a multivariate logistic regression model adjusted for all variables (odds ratio [OR]: 1.22, 95% confidence interval [CI]: 1.15-1.28, P < .001). Furthermore, dividing serum UA into quartiles (Q) revealed an association between elevated serum UA and increased risk of hypertension [Q1 = (OR: 1.00), Q2 = (OR: 1.13, 95% CI: 0.95-1.37, P = .159), Q3 = OR: 1.30, 95% CI: 1.10-1.52, P = .002), Q4 = OR: 1.94, 95% CI: 1.58-2.38, P = .161). Additionally, we conducted subgroup analyses for age, sex, race, education, marital status, diabetes status, smoking, and alcohol use and discovered that these factors had a moderating effect on serum UA and hypertension (P < .05). Last but not least, we looked into the nonlinear link between serum UA and hypertension using weighted restricted cubic splines and discovered that there was no such relationship. The segmental effect of serum UA and hypertension, with an inflection point of 5.079 (mg/dL), was discovered in our gender-stratified study. And in analyses stratified by race and marital status, we similarly found a dose-response relationship between UA and hypertension among Hispanics and unmarried people. Our study showed a positive correlation between serum UA and hypertension.

Assessment of Hypertensive Patients' Complex Metabolic Status Using Data Mining Methods

Cardiovascular diseases are among the leading causes of mortality worldwide. Hypertension is a preventable risk factor leading to major cardiovascular events. We have not found a comprehensive study investigating Central and Eastern European hypertensive patients' complex metabolic status. Therefore, our goal was to calculate the prevalence of hypertension and associated metabolic abnormalities using data-mining methods in our region. We assessed the data of adults who visited the University of Debrecen Clinical Center's hospital (n = 937,249). The study encompassed data from a period of 20 years (2001-2021). We detected 292,561 hypertensive patients. The calculated prevalence of hypertension was altogether 32.2%. Markedly higher body mass index values were found in hypertensive patients as compared to non-hypertensives. Significantly higher triglyceride and lower HDL-C levels were found in adults from 18 to 80 years old. Furthermore, significantly higher serum glucose and uric acid levels were measured in hypertensive subjects. Our study confirms that the calculated prevalence of hypertension is akin to international findings and highlights the extensive association of metabolic alterations. These findings emphasize the role of early recognition and immediate treatment of cardiometabolic abnormalities to improve the quality of life and life expectancy of hypertensive patients.

Association between the Weight-Adjusted Waist Index and Serum Uric Acid: A Cross-Sectional Study

Background

Serum uric acid (SUA) was closely related to body metabolism. This study aimed to investigate the relationship between the adult weight-adjusted waist index (WWI) and SUA.

Methods

In the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2020, 6494 eligible participants aged ≥20  were included. The multivariate logistic regression model was used to test the correlation between WWI and SUA. At the same time, subgroup analysis was carried out by using multivariate logistic regression according to age, sex, and race. Then, the fitting smooth curve was applied to solve the association between WWI and SUA. Finally, the recursive algorithm was used to calculate the inflection point in the nonlinear relationship, and the two-stage piecewise linear regression model was used to analyze the relationship between WWI and SUA on both sides of the inflection point.

Results

In all the 6494 participants, through the fully adjusted model, this study found that there was a positive correlation between WWI and SUA (β = 5.64; 95% CI: 2.62 and 8.66). In addition, this positive correlation still had certain statistical significance in the subgroup analysis stratified by sex, age, and race. Our research team found a significant positive correlation between the WWI and SUA in females, but the correlation was not significant in males. We also found a small inverted U-shaped curve between the WWI and SUA in men when we stratified the sex subgroups. The small inflection point was determined to be 11.5 cm/√ kg. In racial subgroup analysis, we also found a U-shaped relationship between the WWI and SUA in non-Hispanic White and other race/ethnicity (the inflection point was 11.08 cm/√ kg and 12.14 cm/√ kg, respectively).

Conclusion

This study showed that the WWI was a newly developed and new predictor of centripetal obesity independent of body weight and there was a positive correlation between the WWI and SUA.

Research progress on the prevention and treatment of hyperuricemia by medicinal and edible plants and its bioactive components

Hyperuricemia is another common metabolic disease, which is considered to be closely related to the development of many chronic diseases, in addition to the "three highs." Currently, although drugs show positive therapeutic effects, they have been shown to produce side effects that can damage the body. There is growing evidence that medicinal and edible plants and their bioactive components have a significant effect on hyperuricemia. In this paper, we review common medicinal and edible plants with uric acid-lowering effects and summarize the uric acid-lowering mechanisms of different bioactive components. Specifically, the bioactive components are divided into five categories: flavonoids, phenolic acids, alkaloids, polysaccharides, and saponins. These active substances exhibit positive uric acid-lowering effects by inhibiting uric acid production, promoting uric acid excretion, and improving inflammation. Overall, this review examines the potential role of medicinal and edible plants and their bioactive components as a means of combating hyperuricemia, with the hope of providing some reference value for the treatment of hyperuricemia.

Association of first trimester serum uric acid with preeclampsia: an observational cohort study with propensity score matching

To elucidate whether uric acid changes in early pregnancy are associated with the development of preeclampsia and their association with preeclampsia-related adverse pregnancy outcomes. We conducted a retrospective cohort study of 4725 singleton pregnant women between January 2017 and July 2019 using propensity score matching. The primary outcome of the cohort was preeclampsia, and the secondary outcomes were preterm delivery, preterm preeclampsia and low birth weight infants. Multivariable predicted marginal proportions from logistic regression models were used to compute adjusted risk ratios. The quantitative-effect relationship between serum uric acid and preeclampsia development was observed by a dose‒response graph, and the effect of serum uric acid on the week of gestation at delivery was assessed using the Kaplan‒Meier method and the log-rank test. The risk of preeclampsia development increased with higher serum uric acid levels. After adjusting for confounders, the risk ratio for the development of preeclampsia with uric acid levels ≥240 µmol/l was 1.25 (95% CI: 0.96-1.65) compared with the group with uric acid levels <240 µmol/l. In the subgroup analysis of KM (Kaplan-Meier) curves, the gestational week at delivery was earlier when uric acid levels ≥240 µmol/l occurred at 8-12 weeks of gestation. Elevated serum uric acid levels before 20 weeks of gestation are associated with the development of preeclampsia, especially in the first 8-12 weeks of gestation, and the effect is attenuated with increasing gestational weeks, which suggests that elevated uric acid levels in early pregnancy may be a causative factor in preeclampsia. Elevated serum uric acid levels before 20 weeks of gestation are associated with the development of preeclampsia, especially in the early 8-12 weeks of gestation, and the effect attenuates with increasing gestational weeks, which suggest that elevated uric acid in early pregnancy may be a causative factor in preeclampsia.

Association of serum uric acid with benefits of intensive blood pressure control

INTRODUCTION AND OBJECTIVES

Intensive systolic blood pressure (SBP) control improved outcomes in the Strategy of Blood Pressure Intervention in the Elderly Hypertensive Patients (STEP) trial. Whether the serum uric acid concentration at baseline alters the benefits of intensive SBP control is unknown.

METHODS

The STEP trial was a randomized controlled trial that compared the effects of intensive (SBP target of 110 to<130mmHg) and standard (SBP target of 130 to <150mmHg) SBP control in Chinese patients aged 60 to 80 years with hypertension. The primary outcome was a composite of cardiovascular disease events. This post hoc analysis was performed to examine whether the effects of intensive SBP intervention differed by the baseline uric acid concentration using 2 models: restricted cubic spline curves and subgroup analyses, both based on the Fine-Gray subdistribution hazard model in the analysis of the primary outcome and secondary outcomes (excluding all-cause death). In the analysis of all-cause death, the Cox regression model was used. We also examined the change in the follow-up uric acid concentrations.

RESULTS

Overall, the risk of the primary outcome rose as the cumulative uric acid concentration increased in both the intensive and standard treatment groups. Patients with intensive treatment had a lower multivariable-adjusted subdistribution hazard ratio for the primary outcome, but with a wide overlap of 95%CI. Next, we stratified patients according to their baseline uric acid concentration (tertile 1 [T1], <303.0μmol/L; tertile 2 [T2], 303.0 to <375.8μmol/L; and tertile 3 [T3], ≥375.8μmol/L). Subgroup analyses using tertiles provided HRs and 95%CI in T1 (HR, 0.55; 95%CI, 0.36-0.86; P=.008), T2 (HR, 0.80; 95%CI, 0.56-1.14; P=.22) and T3 (HR, 0.86; 95%CI, 0.60-1.21; P=.39), with an interaction P value of .29. The results for most of the secondary outcomes followed the same trends.

CONCLUSIONS

There was no evidence that the benefit of the intensive SBP control differed by baseline uric acid concentrations. This trial was registered at ClinicalTrial.gov (Identifier: NCT03015311).

Folic Acid Protects against Hyperuricemia in C57BL/6J Mice via Ameliorating Gut-Kidney Axis Dysfunction

Emerging lines of research evidence point to a vital role of gut-kidney axis in the development of hyperuricemia (HUA), which has been identified as an increasing burden worldwide due to the high prevalence. The involved crosstalk which links the metabolic and immune-related pathways is mainly responsible for maintaining the axial homeostasis of uric acid (UA) metabolism. Nowadays, the urate-lowering drugs only aim to treat acute gouty arthritis as a result of their controversial clinical application in HUA. In this study, we established the HUA model of C57BL/6J mice to evaluate the effectiveness of folic acid on UA metabolism and further explored the underlying mechanisms. Folic acid attenuated the kidney tissue injury and excretion dysfunction, as well as the typical fibrosis in HUA mice. Molecular docking results also revealed the structure-activity relationship of the folic acid metabolic unit and the UA transporters GLUT9 and URAT1, implying the potential interaction. Also, folic acid alleviated HUA-induced Th17/Treg imbalance and intestinal tissue damage and inhibited the active state of the TLR4/NF-κB signaling pathway, which is closely associated with the circulating LPS level caused by the impaired intestinal permeability. Furthermore, the changes of intestinal microecology induced by HUA were restored by folic acid, including the alteration in the structure and species composition of the gut microbiome community, and metabolite short-chain fatty acids. Collectively, this study revealed that folic acid intervention exerted improving effects on HUA by ameliorating gut-kidney axis dysfunction.

Gene Dose-Dependent and Additive Effects of ABCG2 rs2231142 and SLC2A9 rs3733591 Genetic Polymorphisms on Serum Uric Acid Levels

This study aimed to evaluate whether the single nucleotide polymorphisms of ATP-binding cassette subfamily G member 2 (ABCG2) and solute carrier family 2 member 9 (SLC2A9) affect individual blood uric acid levels using pyrosequencing. ABCG2 (rs2231142, rs72552713, rs2231137), SLC2A9 (rs3734553, rs3733591, rs16890979), and individual uric acid levels were prospectively analyzed in 250 healthy young Korean male participants. Prominent differences in uric acid levels of the alleles were observed in the SLC2A9 rs3733591 polymorphism: wild-type (AA) vs. heterozygote (AG), 0.7 mg/dL (p < 0.0001); AA vs. mutant type (GG), 1.32 mg/dL (p < 0.0001); and AG vs. GG, 0.62 mg/dL (p < 0.01). In ABCG2 single nucleotide polymorphisms (SNPs), the statistically significant differences in uric acid levels were only found in rs2231142 between CC vs. AA (1.06 mg/dL; p < 0.001), and CC vs. CA (0.59 mg/dL; p < 0.01). Serum uric acid levels based on the ABCG2 and SLC2A9 diplotype groups were also compared. The uric acid levels were the lowest in the CC/AA diplotype and highest in the AA/AG diplotype. In addition, the SNP SLC2A9 rs3733591 tended to increase the uric acid levels when the ABCG2 rs2231142 haplotypes were fixed. In conclusion, both the ABCG2 rs2231142 and SLC2A9 rs3733591 polymorphisms may additively elevate blood uric acid levels.

ROS: Basic Concepts, Sources, Cellular Signaling, and its Implications in Aging Pathways

Reactive oxygen species (ROS) are bioproducts of cellular metabolism. There is a range of molecules with oxidizing properties known as ROS. Despite those molecules being implied negatively in aging and numerous diseases, their key role in cellular signaling is evident. ROS control several biological processes such as inflammation, proliferation, and cell death. The redox signaling underlying these cellular events is one characteristic of the new generation of scientists aimed at defining the role of ROS in the cellular environment. The control of redox potential, which includes the balance of the sources of ROS and the antioxidant system, implies an important target for understanding the cells' fate derived from redox signaling. In this review, we summarized the chemical, the redox balance, the signaling, and the implications of ROS in biological aging.

Hypouricemic effect of gallic acid, a bioactive compound from Sonneratia apetala leaves and branches, on hyperuricemic mice

As a tropical medicinal plant, Sonneratia apetala is mainly distributed in the southeast coastal areas of China. Recently, the hypouricemic effect of Sonneratia apetala leaves and branches (SAL) has been reported, but the active compound and its mechanism are unclear. Thus, this study aims to explore the effective fraction of SAL and the mechanism of its active compound on uric acid formation and excretion. SAL was extracted with ethyl acetate and concentrated to obtain solvent-free extracts (SAL-EA). The remains fraction (SAL-E) and the supernatant fraction (SAL-S) of SAL resulting from water extraction and alcohol precipitation were collected and dried. The effects of different fractions were explored on hyperuricemic mice. SAL-S showed excellent activities in decreasing the levels of uric acid (UA), blood urea nitrogen (BUN), and creatinine (CRE) in serum and in attenuating kidney damage. Then, the active compound gallic acid (GA) identified by HPLC was assayed for its mechanism of regulating uric acid metabolism in hyperuricemic mice. The hypouricemic effect of GA was probably associated with the downregulation of URAT1 and GLUT9, upregulation of ABCG2 and decreased activities of adenosine deaminase (ADA) and xanthine oxidase (XOD). Moreover, GA suppressed the level of MDA, IL-6, IL-1β, TNF-α, TGF-β1, COX-2 and cystatin-C (Cys-C), and enhanced the activities of SOD, GSH-Px, CAT, and Na⁺-K⁺-ATPase (NKA) in the kidneys. These results indicated that GA protects against hyperuricemia-induced kidney injury via suppressing oxidative stress and inflammation as well as decreasing the serum levels of UA by regulating urate transporters.

Association of serum uric acid levels with cardiovascular and all-cause mortality in hypertensive patients in China: a cohort study

Purpose

The present study aimed to assess the association of elevated serum uric acid (SUA) and hypouricemia with all-cause mortality and cardiovascular mortality in Chinese hypertensive patients.

Methods

In the present prospective cohort, 9325 hypertensive patients from Dongguan, China were enrolled from 2014 to 2018 for analysis. Participants were categorised by quintiles of SUA. The HRs and 95% CIs for the association between SUA, all-cause and cardiovascular mortality were evaluated using the multivariate Cox regression model. After adjusting for multiple confounders, restricted cubic spline analysis was conducted to demonstrate the shape of relationship.

Results

After a median follow-up of 4.18 years for 9325 participants, there were 409 (4.4%) and 151 (1.6%) reported cases of all-cause and cardiovascular mortality, respectively. By using the third quintile of SUA (6.68 mg/dL to <7.55 mg/dL for men, 5.63 mg/dL to <6.42 mg/dL for women) as reference, the highest quintiles of SUA were associated with an elevated risk of all cause (HR: 1.34, 95% CI 1.00 to 1.80) in the crude model, but the association was not significant after adjusting for multiple comparisons. The association between low SUA and mortality and the dose–response analysis on the non-linearity of SUA–mortality relationship were not statistically significant.

Conclusions

Although the association between SUA levels, all-cause and cardiovascular disease mortality did not appear to be significant among Chinese hypertensive patients, the findings might be confounded by their medical conditions. Further studies are needed to verify the optimal SUA levels for hypertensive patients.

Dietary fructose and high salt in young male Sprague Dawley rats induces salt-sensitive changes in renal function in later life

Dietary fructose and salt are associated with hypertension and renal disease. Dietary input during critical postnatal periods may impact pathophysiology in maturity. The highest consumption of fructose occurs during adolescence. We hypothesized that a diet high in fructose with or without high salt in young male Sprague Dawley rats will lead to salt-sensitive hypertension, albuminuria, and decreased renal function in maturity. Four groups were studied from age 5 weeks: 20% glucose + 0.4% salt (GCS-GCS) or 20% fructose + 4% salt throughout (FHS-FHS). Two groups received 20% fructose + 0.4% salt or 20% fructose + 4% salt for 3 weeks (Phase I) followed by 20% glucose + 0.4% salt (Phase II). In Phase III (age 13-15 weeks), these two groups were challenged with 20% glucose + 4% salt, (FCS-GHS) and (FHS-GHS), respectively. Each group fed fructose in Phase I exhibited significantly higher MAP than GCS-GCS in Phase III. Net sodium balance, unadjusted, or adjusted for caloric intake and urine flow rate, and cumulative sodium balance were positive in FHS during Phase I and were significantly higher in FCS-GHS, FHS-GHS, and FHS-FHS vs GCS-GCS during Phase III. All three groups fed fructose during Phase I displayed significantly elevated albuminuria. GFR was significantly lower in FHS-FHS vs GCS-GCS at maturity. Qualitative histology showed mesangial expansion and hypercellularity in FHS-FHS rats. Thus, fructose ingestion during a critical period in rats, analogous to human preadolescence and adolescence, results in salt-sensitive hypertension and albuminuria in maturity. Prolonged dietary fructose and salt ingestion lead to a decline in renal function with evidence suggestive of mesangial hypercellularity.

Correlation of obesity, dietary patterns, and blood pressure with uric acid: data from the NHANES 2017-2018

BACKGROUND

Prevalence rates of hyperuricemia and gout are increasing. Clinical investigations of hyperuricemia-related risk factors aid in the early detection, prevention, and management of hyperuricemia and gout. Ongoing research is examining the association of obesity, dietary patterns, and blood pressure (BP) with serum uric acid (sUA).

METHODS

A cross-sectional study was conducted based on the National Health and Nutrition Examination Survey. The exposures included body mass index (BMI), dietary patterns, and BP. The outcome variable was sUA level. The weighted multivariate linear regression models and smooth curve fittings were used to assess the association of BMI, dietary patterns, and BP with sUA.

RESULTS

There was a significantly positive correlation between BMI and sUA (β = 0.059, 95% CI: 0.054 to 0.064, P < 0.00001). Overweight and obese individuals had higher sUA levels than those with the normal BMI (β = 0.451, 95% CI: 0.357 to 0.546, P < 0.00001; β = 0.853, 95% CI: 0.760 to 0.946, P < 0.00001; respectively). Dietary energy intake was positively correlated with sUA (β = 0.000, 95% CI: 0.000 to 0.000, P = 0.01057). Dietary intake of carbohydrate and fiber were negatively correlated with sUA (β = - 0.001, 95% CI: - 0.002 to - 0.000, P < 0.00001; β = - 0.008, 95% CI: - 0.011 to - 0.004, P = 0.00001; respectively). Moreover, systolic BP was positively correlated with sUA (β = 0.006, 95% CI: 0.003 to 0.009, P = 0.00002). However, no statistical differences were found about the associations of dietary intake of total sugars, protein, total fat, cholesterol, and diastolic BP with sUA.

CONCLUSIONS

The current cross-sectional investigation of a nationally representative sample of US participants showed that BMI, dietary energy intake, and systolic BP were positively correlated with sUA levels; dietary carbohydrate and fiber intake were negatively correlated with sUA levels. The findings might be helpful for the management and treatment of hyperuricemia and gout.

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.

Association of Total Calcium With Serum Uric Acid Levels Among United States Adolescents Aged 12-19 Years: A Cross-Sectional Study

Aims

Evidence of a link between total calcium (CA) and serum uric acid (SUA) is absent in adolescents. Thus, this study aimed to determine the relationship between total CA levels and SUA levels in United States adolescents.

Methods

A cross-sectional study analyzed a sample composed of 8,309 United States adolescents aged 12–19 years from the National Health and Nutrition Examination Survey database (1999–2006 survey cycle). Multivariable linear regression analyses and multivariable logistic regression analyses were used to assess the correlation of total CA with SUA levels and hyperuricemia. Furthermore, the dose-response relationship of total CA and SUA levels was analyzed using smooth curve fitting (penalized spline method).

Results

According to multivariable linear regression analysis, every 1 mg/dL increase in total CA level is associated with a 0.33 mg/dL (β = 0.33, 95% CI: 0.27–0.40, p < 0.001) increase in SUA. Multivariable logistic regression analyses showed that every 0.1 mg/dL increase in total CA level is linked with an 8% increased risk of hyperuricemia (OR = 1.08, 95% CI: 1.06–1.10, p < 0.001). The analyses of smooth curve fitting revealed that total CA levels were linearly correlated with SUA levels (P_{non–linearity} = 0.152). The results were highly stable in all subgroups. The interaction analysis results presented that race/ethnicity had an interactive role in associating total CA with SUA levels.

Conclusions

In United States adolescents, total CA levels were linearly and positively correlated with SUA levels.

The Association Between Total Percent Fat and Serum Uric Acid in Adults

Background

Serum uric acid (SUA) has been proven to be closely associated with metabolic abnormalities, including obesity. This study aimed to investigate the detailed relationship between total percent fat (TPF) and SUA among adults.

Methods

Briefly, 23,715 adults aged 18–59 years in the National Health and Nutrition Examination Survey (NHANES) 1999–2018 were included in this study. Multivariable linear regression models were used to examine the association between TPF and SUA. Subgroup analyses stratified by sex and obesity status were also performed by multivariable linear regression. Then, fitted smoothing curves and generalized additive models were also applied to address the non-linear relationship between TPF and SUA. Finally, a recursive algorithm was used to calculate the inflection point in the non-linear relationship and a two-segment piecewise linear regression model was used to analyze the relationship between TPF and SUA on both sides of the inflection point.

Results

There were 15,808 (66.7%) obese individuals in all 23,715 participants. In the fully adjusted model, there was a positive association between TPF and SUA (β = 0.99, 95% CI: 0.73–1.26). Besides, this positive association remained statistically significant in subgroup analyses stratified by sex and obesity status. Interestingly, in males, the association of TPF and SUA was an inverted U-shaped curve (inflection point: 34.3%).

Conclusion

Our study revealed a significant positive relationship between TPF and SUA among adults and this association remained statistically significant when stratified by sex and obesity status, but the shape of the smoothing curve in males differed from that in females.

Serum 25-hydroxyvitamin D might be negatively associated with hyperuricemia in U.S. adults: an analysis of the National Health and Nutrition Examination Survey 2007-2014

PURPOSE

The results of previous studies on the relationship between serum 25-hydroxyvitamin D [25(OH)D] and hyperuricemia are controversial. We hypothesized that serum 25(OH)D concentrations of U.S. adults would negatively correlate with the risk of hyperuricemia.

METHOD

Data came from the National Health and Nutrition Examination Survey 2007-2014 were used, after excluding those who met at least one of the exclusion criteria, a total of 9096 male individuals and 9500 female individuals aged 18 years or older were included. Binary logistic regression analysis and restricted cubic spline with fully adjusted confounding factors were applied to evaluate the association between serum 25(OH)D and hyperuricemia. We further performed stratified analysis and sensitivity analysis to minimize the influence of gender, metabolic syndrome, obesity and renal dysfunction on the above association.

RESULTS

We found a negative correlation between serum 25(OH)D and hyperuricemia. In the binary logistic regression analysis, compared with the highest serum 25(OH)D quartile [Q4: 25(OH)D > 77.10 nmol/L] group, the odds ratios (95% confidence intervals) in the lowest quartile [Q1: 25(OH)D ≤ 43.20 nmol/L] was 1.46 (1.22-1.75) in the fully adjusted model. Restricted cubic spline analysis showed L-shaped and non-linear relationships between 25(OH)D and hyperuricemia. In sensitivity analysis, after restricting to participants without significant renal dysfunction and obesity, the above association remained significant. After restricting to participants who were diagnosed as metabolic syndrome, above association remained significant in the fully adjusted model. In stratified analysis by gender, the association remained significant among males and females.

CONCLUSIONS

Serum 25(OH)D might be inversely associated with hyperuricemia in general U.S. adults. From our study, for people with unexplained hyperuricemia, screening for serum Vitamin D concentration might be necessary.

Are Differences in Inflammatory Markers between Patients with and without Hypertension-Mediated Organ Damage Influenced by Circadian Blood Pressure Abnormalities?

We aimed to explore the influence that the circadian blood pressure (BP) profile could exert on the correlation between some inflammatory markers and hypertension-mediated organ damage (HMOD). This was a cross-sectional study that included patients with primary arterial hypertension older than 18 years old. We included some parameters of 24 h ambulatory blood pressure monitoring collection and several inflammatory markers, as follows: platelet count (PTC), erythrocyte sedimentation rate (ESR), ultrasensitive C-reactive-protein, ferritin, fibrinogen, and uric acid. Myocardial hypertrophy, albuminuria, carotid intima-media thicknesses and ankle brachial index were assessed as HMOD presentations. Individuals were divided into two groups: patients with and without HMOD. We included 522 patients (47% women, mean age of 54 years). Multivariate logistic regression analysis showed that male patients older than 50 years old with uric acid levels above 7 mg/dL, ESR higher than 20 mm/h, fibrinogen greater than 320 mg/dL and PTC lower than 275 × 103/µL were associated with HMOD (p < 0.05). The circadian BP profile (dipper versus non-dipper pattern) did reach neither statistical significance nor influence the odds ratio of those inflammatory markers for HMOD. We found that differences in some inflammatory markers between patients with and without HMOD were not explained by a different circadian BP profile.

Serum Uric Acid Might Be Positively Associated With Hypertension in Chinese Adults: An Analysis of the China Health and Nutrition Survey

Background: Previous studies have clarified the relationship between serum uric acid (SUA) and hypertension; most of previous studies suggest that elevated uric acid levels are associated with an increased risk of hypertension, while in China, there are relatively few studies to explore above association. The objective of this longitudinal study is to investigate the correlation of SUA and hypertension in Chinese adults with a nationwide large-scale sample.

Methods: Data from the China Health and Nutrition Survey 2009, 2011, and 2016 were used; a total of 8,469 participants (3,973 men and 4,496 women) were involved. This study was conducted separately by gender. Clinical characteristics of the participants among different uric acid groups are compared. The binary logistic regression analysis was conducted to examine the association between SUA and hypertension. Restricted cubic spline analysis with three knots of the SUA concentration were used to characterize the dose-response relationship. Additionally, we compared the incidence of hypertension in the different baseline uric acid groups during follow-up in 2011 and 2015.

Results: After the covariates were fully adjusted, we found that elevated uric acid levels were correlated with increased risk of hypertension in both males (p < 0.01) and females (p < 0.01). With 2-year or 6-year of follow-up, we found participants with higher baseline uric acid levels had a higher incidence of hypertension (p < 0.01). In stratified analysis by obesity, above relationship remained significant in nonobesity population (males: p < 0.05, females: p < 0.01) and became nonsignificant in obesity people. In stratified analysis by age, above positively correlation remained significant in middle-aged men (p < 0.05) and elderly women (p < 0.01). Restricted cubic spline revealed the dose-response relationship between SUA and hypertension; we also found that above relationship was much stronger in females.

Conclusion: This study suggests that elevated SUA levels might be positively associated with an increased risk of hypertension in general Chinese adults.

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

OBJECTIVE

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

DESIGN

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

SETTING/PATIENTS

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

OUTCOME MEASURES

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

RESULTS

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

CONCLUSIONS

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

Associations of plasma multiple metals with risk of hyperuricemia: A cross-sectional study in a mid-aged and older population of China

BACKGROUND

Metal exposures are suspected to associate with the risk of hyperuricemia (HUA), but the current results are still conflicting.

OBJECTIVE

To investigate the associations between multiple plasma metal exposures and HUA risk.

METHODS

A cross-sectional study was conducted in 1406 Chinese Han adults who underwent routine physical examination in the Eighth Affiliated Hospital of Sun Yat-Sen University in Shenzhen. The plasma levels of 13 metals were measured by the inductively coupled plasma mass spectrometry (ICP-MS). Multivariable logistic, linear regression models, least absolute shrinkage and selection operator (LASSO) penalized regression analysis, and restricted cubic spline (RCS) models were applied to assess the associations.

RESULTS

The median plasma uric acid concentration in HUA group (434 μmol/L) was significantly higher than that in non-HUA group (305 μmol/L). The multivariate-adjusted odds ratios (95% confidence intervals) of HUA were 1.62(1.08-2.43) for magnesium, 1.61(1.05-2.47) for copper, 1.62(1.06-2.49) for zinc, 1.87(1.26-2.81) for arsenic, 1.50(1.01-2.23) for selenium, and 1.70(1.16-2.49) for thallium based on the single-metal logistic regression models, comparing the highest versus the lowest quartile of metal levels. Further multi-metal logistic, linear regression models and the LASSO analysis all indicated positive associations of zinc, arsenic with HUA risk or uric acid levels. RCS model indicated an inverted V-shaped positive association between zinc levels and HUA risk (p for non-linearity = 0.048, p for overall association = 0.022), while arsenic levels showed a positive and linear dose-response relationship with HUA risk (p for non-linearity = 0.892, p for overall association<0.001).

CONCLUSIONS

Higher plasma levels of zinc and arsenic might increase HUA risk and showed positive dose-response relationships. Further cohort studies in larger population are required to testify our findings.

Therapeutic enzymes as non-conventional targets in cardiovascular impairments:A Comprehensive Review

Over the last few decades, substantial progress has been made towards the understanding of cardiovascular diseases (CVDs). In-depth mechanistic insights have also provided opportunities to explore novel therapeutic targets and treatment regimens to be discovered. Therapeutic enzymes are an example of such opportunities. The balanced functioning of such enzymes protects against a variety of CVDs while on the other hand, even a small shift in the normal functioning of these enzymes may lead to deleterious outcomes. Owing to the great versatility of these enzymes, inhibition and activation are key regulatory approaches to counter the onset and progression of several cardiovascular impairments. While cardiovascular remedies are already available in excess and of course they are efficacious, a comprehensive description of novel therapeutic enzymes to combat CVDs is the need of the hour. In light of this, the regulation of the functional activity of these enzymes also opens a new avenue for the treatment approaches to be employed. This review describes the importance of non-conventional enzymes as potential candidates in several cardiovascular disorders while highlighting some of the recently targeted therapeutic enzymes in CVDs.

Incident hyperuricemia in relation to antihypertensive therapy with the irbesartan/hydrochlorothiazide combination

OBJECTIVE

We investigated serum uric acid changes and incident hyperuricemia in relation to the achieved blood pressure (BP) after 12 weeks of antihypertensive therapy with the irbesartan/hydrochlorothiazide combination.

METHODS

The study participants were 449 patients who completed the study. Analysis of covariance and multiple logistic regression analyses were performed to calculate the least square mean changes (± standard error) from baseline in serum uric acid and odds ratios (ORs) for incident hyperuricemia according to the achieved levels of BP.

RESULTS

Adjusted analyses showed that serum uric acid changes differed according to the achieved SBP/DBP (P = 0.002), with a smaller mean (± standard error) increase in the range of 130-139/<90 mm Hg (n = 132, 19.8 ± 5.7 µmol/L) than that of ≥140/90 (n = 129, 32.4 ± 7.3 µmol/L) or <130/90 mm Hg (n = 188, 39.5 ± 5.1 µmol/L). Adjusted analyses showed similar results for the incident hyperuricemia (n = 95, 24.0%) in those patients with normal serum uric acid at baseline (n = 396). The risk of incident hyperuricemia was lower (OR, 0.45; 95% confidence interval 0.25-0.83; P = 0.04) in patients with an achieved SBP/DBP of 130-139/<90 mm Hg (n = 117, incidence rate, 17.1%) than those with an achieved SBP/DBP of ≥140/90 (n = 118, 31.4%) or <130/90 mm Hg (n = 161, 23.6%).

CONCLUSIONS

Thiazide-induced changes in serum uric acid or incident hyperuricemia were associated with the achieved SBP/DBP, being lower at the level of 130-139/<90 mm Hg.

Recent Updates of Natural and Synthetic URAT1 Inhibitors and Novel Screening Methods

Human urate anion transporter 1 (hURAT1) is responsible for the reabsorption of uric acid in the proximal renal tubules and is a promising therapeutic target for treating hyperuricemia. To mitigate the side effects of URAT1-targeted clinical agents such as benzbromarone, there is significant interest in discovering new URAT1 inhibitors and developing technology that can evaluate URAT1 inhibition. This review summarizes the methods for assay of URAT1 inhibition and the progress on the discovery of natural and synthetic URAT1 inhibitors in the past five years.

Association of uric acid and uric acid to creatinine ratio with chronic kidney disease in hypertensive patients

Background

Recent studies have shown that the serum uric acid/creatinine ratio (SUA/SCr) is a better predictor of chronic kidney disease (CKD) than serum uric acid (SUA) isolated. The aim of the present study was to evaluate the association of isolated SUA and the SUA/SCr with CKD in hypertensive patients.

Methods

Cross-sectional study conducted with hypertensive patients followed-up by the Primary Health Care Service (PHC). Sociodemographic, economic, lifestyle, clinical, anthropometric, and biochemical variables were evaluated. The association between SUA parameters (quartiles of SUA and quartiles of SUA/SCr) and CKD was evaluated by bivariate and multivariate logistic regression. The association between SUA parameters (SUA and SUA/SCr) and estimated glomerular filtration rate (eGFR) was evaluated by linear regression. The analyses were performed considering four adjustment models. SUA and SUA/SCr were compared by receiver operating characteristic (ROC) curve.

Results

In the fully adjusted model, SUA was positively associated with the presence of CKD (OR = 6.72 [95 % CI 1.96–22.96]) and inversely associated with eGFR (β Coef. = -2.41 [95 % CI -3.44; -1.39]). SUA/SCr was positively associated with eGFR (β Coef. = 2.39 [1.42; 3.36]). According to the ROC curve, the SUA is a better predictor of CKD than the SUA/SCr.

Conclusions

Elevated levels of isolated SUA were associated with CKD and eGFR. However, the SUA/SCr was not associated with CKD. We do not recommend using the SUA/SCr to predict CKD in hypertensive patients.

Identification of Potential Metabolic Markers of Hypertension in Chinese Children

Background

Studies in adults have shown that several metabolites across multiple pathways are strongly associated with hypertension. However, as yet, to our knowledge, no study has investigated such association in childhood. We, therefore, compared the serum metabolite profile of children with normal and elevated blood pressure (BP) to identify potential metabolic markers and pathways that could be useful for the assessment of pediatric hypertension.

Methods

The study included 26 hypertensive children (age range, 6-11 years) and 26 age- and sex-matched ones with normal BP, who were recruited from the baseline survey of the Huantai Childhood Cardiovascular Health Cohort Study. Ultrahigh-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry was performed to assess the serum metabolite profile. Logistic regression analysis was used to select significant metabolites associated with hypertension after adjustment for body mass index, waist circumference, and lipid profile. Kyoto Encyclopedia of Genes and Genomes (KEGG) and MetaboAnalyst were utilized to search for the potential pathways of metabolites.

Results

A total of 45 and 34 metabolites were preliminarily screened in positive and negative modes, respectively (variable importance in the projection (VIP) > 1.0 and P < 0.05). After adjustment for the false discovery rate, 7 and 1 differential metabolites in the positive and negative modes, respectively, remained significant (VIP > 1.0 and q < 0.05). These metabolites were mainly involved in amino acid metabolism and glycerophospholipid metabolism. Among these, two significant metabolites including ethanolamine and 2-methyl-3-hydroxy-5-formylpyridine-4-carboxylate displayed an area under the curve value of 0.820 (95% confidence interval, 0.688-0.951), with a sensitivity of 0.846 and a specificity of 0.769.

Conclusion

The untargeted metabolomics approach effectively identified the differential serum metabolite profile in children with and without hypertension. Notably, two metabolites including ethanolamine and 2-methyl-3-hydroxy-5-formylpyridine-4-carboxylate exhibited a good discriminative ability to identify children with hypertension, providing new insights into potential mechanisms of pediatric hypertension.

Acute effects of hypouricemia on endothelium, oxidative stress, and arterial stiffness: A randomized, double-blind, crossover study

We hypothesized acute moderate and drastic reductions in uric acid concentration exert different effects on arterial function in healthy normotensive and hypertensive adults. Thirty-six adults (aged 58 [55;63] years) with or without primary hypertension participated in a three-way, randomized, double-blind, crossover study in which [placebo] and [febuxostat] and [febuxostat and rasburicase] were administered. Febuxostat and rasburicase reduce the uric acid concentration by xanthine oxidoreductase inhibition and uric acid degradation into allantoin, respectively. Endothelial function was assessed in response to acetylcholine, sodium nitroprusside, heating (with and without nitric oxide synthase inhibition) using a laser Doppler imager. Arterial stiffness was determined by applanation tonometry, together with blood pressure, renin-angiotensin system activity, oxidative stress, and inflammation. Uric acid concentration was 5.1 [4.1;5.9], 1.9 [1.2;2.2] and 0.2 [0.2;0.3] mg/dL with [placebo], [febuxostat] and [febuxostat-rasburicase] treatments, respectively (p < 0.0001). Febuxostat improved endothelial response to heat particularly when nitric oxide synthase was inhibited (p < 0.05) and reduced diastolic and mean arterial pressure (p = 0.008 and 0.02, respectively). The augmentation index decreased with febuxostat (ANOVA p < 0.04). Myeloperoxidase activity profoundly decreased with febuxostat combined with rasburicase (p < 0.0001). When uric acid dropped, plasmatic antioxidant capacity markedly decreased, while superoxide dismutase activity increased (p < 0.0001). Other inflammatory and oxidant markers did not differ. Acute moderate hypouricemia encompasses minor improvements in endothelial function, blood pressure, and arterial stiffness. Clinical Trial Registration: NCT03395977, https://clinicaltrials.gov/ct2/show/NCT03395977.

Fructose Consumption-Free Sugars and Their Health Effects

BACKGROUND

The excessive consumption of free sugars, including fructose, is considered a cause of overweight and metabolic syndrome throughout the Western world. In Germany, the prevalence of overweight and obesity among adults (54%, 18%) and children (15%, 6%) has risen in the past few decades and has now become stable at a high level. The causative role of fructose is unclear.

METHODS

This review is based on publications retrieved by a selective search in PubMed and the Cochrane Library, with special attention to international guidelines and expert recommendations.

RESULTS

The hepatic metabolism of fructose is insulin-independent; because of the lack of a feedback mechanism, it leads to substrate accumulation, with de novo lipogenesis and gluconeogenesis. Recent meta-analyses with observation periods of one to ten weeks have shown that the consumption of fructose in large amounts leads to weight gain (+ 0.5 kg [0.26; 0.79]), elevated triglyceride levels (+ 0.3 mmol/L [0.11; 0.41]), and steatosis hepatis (intrahepatocellular fat content: + 54% [29; 79%]) when it is associated with a positive energy balance (fructose dose + 25-40% of the total caloric requirement). Meta-analyses in the isocaloric setting have not shown any comparable effects. Children, with their preference for sweet foods and drinks, are prone to excessive sugar consumption. Toddlers under age two are especially vulnerable.

CONCLUSION

The effects that have been observed with the consumption of large amounts of fructose cannot be reliably distinguished from the effects of a generally excessive caloric intake. Further randomized and controlled intervention trials of high quality are needed in order to determine the metabolic effects of fructose consumed under isocaloric conditions. To lessen individual consumption of sugar, sugary dietary items such as sweetened soft drinks, fruit juice, and smoothies should be avoided in favor of water as a beverage and fresh fruit.

Anti-Hyperuricemic and Nephroprotective Effects of Dihydroberberine in Potassium Oxonate- and Hypoxanthine-Induced Hyperuricemic Mice

Phellodendri Chinese Cortex has long been used to treat hyperuricemia and gout. Berberine (BBR), its characteristic ingredient, has also been shown to be effective in alleviating monosodium urate crystals-triggered gout inflammation in vitro and in vivo. Dihydroberberine (DHB) is a hydrogenated derivative of BBR that showed improved in vivo efficacy on many metabolic disorders. However, its anti-hyperuricemia effect remains underexplored. In the present work, the hypouricemic and renoprotective effects of DHB on hyperuricemic mice were investigated. The hyperuricemic mice model was induced by intraperitoneal injection of potassium oxonate (PO, 300 mg/kg) combined with intragastric administration of hypoxanthine (HX, 300 mg/kg) for 7 days. Different dosages of DHB (25, 50 mg/kg), BBR (50 mg/kg) or febuxostat (Feb, 5 mg/kg) were orally given to mice 1 h after modeling. The molecular docking results showed that DHB effectively inhibited xanthine oxidase (XOD) by binding with its active site. In vitro, DHB exhibited significant XOD inhibitory activity (IC₅₀ value, 34.37 μM). The in vivo results showed that DHB had obvious hypouricemic and renoprotective effects in hyperuricemic mice. It could not only lower the uric acid and XOD levels in serum, but also suppress the activities of XOD and adenosine deaminase (ADA) in the liver. Furthermore, DHB noticeably down-regulated the renal mRNA and protein expression of XOD. Besides, DHB remarkably and dose-dependently ameliorated renal damage, as evidenced by considerably reducing serum creatinine and blood urea nitrogen (BUN) levels, inflammatory cytokine (TNF-α, IL-1β, IL-6 and IL-18) levels and restoring kidney histological deteriorations. Further mechanistic investigation showed that DHB distinctly down-regulated renal mRNA and protein levels of URAT1, GLUT9, NOD-like receptor 3 (NLRP3), apoptosis-associated speck-like (ASC), caspase-1 and IL-1β. Our study revealed that DHB had outstanding hypouricemic and renoprotective effects via suppressing XOD, URAT1, GLUT9 and NLRP3 inflammasome activation in the kidney.

[Association between serum uric acid and subclinical cardiac damage in children with primary hypertension]

OBJECTIVE

To evaluate the condition of subclinical cardiac damage in children with primary hypertension and the association between serum uric acid and subclinical cardiac damage.

METHODS

A retrospective analysis was performed on the medical data of 55 children who were hospitalized and diagnosed with primary hypertension in the Department of Cardiology, Children's Hospital of Soochow University from January 2015 to June 2020. Forty-five healthy children, matched for age and sex, were enrolled as the control group. The two groups were compared in terms of clinical features, laboratory examination, and parameters for left ventricular structure, systolic function, and diastolic function. The correlation of serum uric acid with the parameters for left ventricular structure, systolic function, and diastolic function in children with primary hypertension was analyzed.

RESULTS

Compared with the control group, the hypertension group had significantly higher left ventricular mass (LVM), left ventricular mass index (LVMI), and relative wall thickness (RWT) (P < 0.05). Among the children with primary hypertension, 20 (36%) had left ventricular hypertrophy. The hypertension group had significantly larger left atrial diameter and aortic root diameter than the control group (P < 0.05). The hypertension group had a significantly higher ratio of early diastolic mitral inflow velocity to early diastolic mitral annular velocity than the control group (P < 0.05). The correlation analysis showed that in children with primary hypertension, serum uric acid was positively correlated with LVM (r=0.534, P < 0.01), left atrial diameter (r=0.459, P < 0.01), and aortic root diameter (r=0.361, P=0.010). After adjustment for blood pressure, serum uric acid was still positively correlated with the above parameters (P < 0.05).

CONCLUSIONS

Children with primary hypertension may have subclinical cardiac damage such as left ventricular hypertrophy, left ventricular diastolic dysfunction, left atrial enlargement, and proximal aortic dilation. Elevated serum uric acid is significantly associated with cardiac damage in children with primary hypertension.

Expression, localization and metabolic function of "resurrected" human urate oxidase in human hepatocytes

A high serum uric acid (SUA) concentration is associated with hyperuricemia (HUA) and gout. In order to obtain long-acting therapeutic effect, correction of purine metabolism at genetic level is advantageous. For this purpose, we expressed three "human-like" urate oxidases in human hepatocytes (HL-7702) by lentivirus-mediated transduction. Enzymatic assay revealed that the recombinant urate oxidases expressed in HL-7702 cells were functionally active. Electron microscopy study showed that the recombinant enzymes were localized to peroxisome and formed distinct crystalloid core structures as in other mammal cells. Although similar rate of uric acid degradation was observed for all recombinant urate oxidases, HL-7702-pLVX-UOX₈₃ cells and HL-7702-pLVX-UOX_214/217 cells retained more cell viability compared with HL-7702-pLVX-UOX_PBC at high uric acid level. This study provides a new direction for the treatment of gout and hyperuricemia.

Higher serum uric acid is associated with higher risks of thrombosis and death in patients with primary myelofibrosis

BACKGROUND

Serum uric acid (SUA) can promote inflammation and is associated with increased cardiovascular morbidity. Primary (PMF) and secondary myelofibrosis (SMF) are myeloproliferative neoplasms characterized by high cellular turnover and substantial risk of thrombosis and death.

METHODS

We have retrospectively investigated SUA in 173 patients with myelofibrosis (125 PMF; 48 SMF) and 30 controls.

RESULTS

The PMF patients had significantly higher SUA in comparison to SMF and controls. In both PMF and SMF higher SUA was significantly associated with arterial hypertension and decreased renal function. Among PMF patients, higher SUA was significantly associated with older age, larger spleen, higher white blood cell counts, higher lactate dehydrogenase, lower immunoglobulin G levels, allopurinol use and non-smoking. Among SMF patients, higher SUA was associated with male sex (P < 0.05 for all analyses). In PMF higher SUA was univariately associated with inferior survival (> 427 μmol/L hazard ratio (HR) = 2.22; P = 0.006) and shorter time to thrombosis (> 444 μmol/L HR = 5.05; P = 0.006), which could be shown separately for arterial (> 380 μmol/L; HR = 4.9; P = 0.013) and venous thromboses (> 530 μmol/L; HR = 17.9; P < 0.001). In multivariate analyses, SUA remained significantly associated with inferior survival independent of the Dynamic International Prognostic Staging System and with shorter time to thrombosis independent of age in PMF patients; however, the prognostic significance of SUA was diminished after including serum creatinine in the models. SUA was not prognostic in SMF patients.

CONCLUSION

The PMF patients present with higher SUA levels, which are associated with features of more advanced disease and higher risks of arterial and venous thrombosis and death.

Association Between Metabolic Associated Fatty Liver Disease and Chronic Kidney Disease: A Cross-Sectional Study from NHANES 2017-2018

PURPOSE

In 2020, an international expert consensus proposed a novel concept, defined as metabolic associated fatty liver disease (MAFLD). We aimed to investigate the association between MAFLD and chronic kidney disease (CKD).

METHODS

A total of 4869 subjects with demographic data, laboratory tests, and ultrasound transient elastography from National Health and Nutrition Examination Surveys of the United States (NHANES) 2017-2018 were included in the study. Statistical analysis was performed to test the independent association between the demographic data, laboratory tests, and non-invasive liver fibrosis scores in subjects with different subgroups of MAFLD.

RESULTS

A total of 4869 subjects were identified in the NHANES 2017-2018, of which 1032 (21.2%) subjects were diagnosed with CKD. There was a higher prevalence of CKD in MAFLD subjects than in non-MALFD subjects (22.2% vs 19.1, p=0.048). After 1:1 propensity score matching by gender, age and race, we enrolled 1983 subjects with MAFLD diagnosed based on liver ultrasound transient elastography and 1983 PS-matched subjects without MAFLD. MAFLD was not independently associated with CKD after PSM. Further investigation showed that age (OR: 1.05, 95% CI: 1.03~1.05, p<0.001), hypertension (OR: 1.66, 95% CI: 1.38~2.00, p<0.001), DM (OR: 2.21, 95% CI: 1.89~3.11, p<0.001), hyperuricemia (OR: 1.91, 95% CI: 1.55~2.36, p<0.001), ALP (OR: 1.00, 95% CI: 1.00~1.01, p=0.010), and FIB-4 score (OR: 1.23, 95% CI: 1.05~1.01, p=0.011) were independently associated with CKD. In the subgroup analysis, the subgroups of MAFLD complicated with DM, age, hypertension, and hyperuricemia were independently related to the incidence of CKD. In the subgroup of DM without MAFLD, age, hyperuricemia, ALP, and NFS score were independently related to the incidence of CKD. In the subgroup of MAFLD without DM, age, hypertension, hyperuricemia, and ALP were independently related to the incidence of CKD.

CONCLUSION

Based on the NHANES 2017-2018, MAFLD was not independently associated with CKD. Thus, the link between MAFLD and CKD may be mediated by metabolic abnormalities, such as diabetes mellitus and hyperuricemia.

Renal lipid accumulation, oxidative stress and uric acid handling in a rodent model of obesity and metabolic syndrome

Hyperuricemia is more prevalent among people with obesity and metabolic syndrome, and is associated with adverse clinical outcomes. We hypothesized that increased renal reabsorption of uric acid (UA) in obesity and metabolic syndrome may be an adaptive response of the kidney when faced with fatty acid-induced oxidative stress. To test this hypothesis, we examined lipid accumulation, markers of oxidative stress, and renal UA handling in Zucker diabetic fatty (ZDF) rats, and in matched lean control animals. Rats were randomized to either normal rodent chow or a diet supplemented with antioxidants (α-tocopheryl acetate, sodium selenite, zinc sulfate, and ascorbic acid), and were followed up for either 4 or 20 weeks after randomization. Dietary antioxidant supplementation had no significant effects in lean control rats but led to partial improvement in markers of elevated oxidative stress in the kidney of ZDF rats. Renal UA handling was not affected by antioxidant supplementation. We observed robust correlations between renal lipid content and oxidative stress markers in the pooled experimental groups, particularly in older animals after 20 weeks on the study diets. Dietary antioxidant supplementation did not prevent the gradual decline in renal function observed in older ZDF rats. These findings suggest that hyperuricemia in the ZDF rat model of obesity and the metabolic syndrome is not caused by renal oxidative stress, that there may be a pathophysiological link between lipid accumulation and oxidative stress in the kidney, and that antioxidant supplementation does not prevent age-related decline in renal function in ZDF rats.

Ambulatory blood pressure in relation to interaction between dietary sodium intake and serum uric acid in the young

PURPOSE

We hypothesise that dietary sodium intake interacts with serum uric acid to influence blood pressure (BP) in children and adolescents. In the present study, we investigated ambulatory BP in relation to hyperuricaemia, dietary sodium intake and their interaction in children and adolescents with hypertension.

MATERIALS AND METHODS

A total of 616 study participants were 10-24 years old and had primary hypertension diagnosed after admission in a specialised inpatient ward. Ambulatory BP monitoring was performed during hospitalisation. 24-h urine was collected for measurements of electrolytes. Hyperuricaemia was defined as a serum uric acid of ≥327.25 μmol/L in patients <18 years old and of ≥420 and ≥360 μmol/L, respectively, in male and female patients ≥18 years old.

RESULTS

In adjusted analyses, patients with hyperuricaemia (n = 283), compared with those with normal serum uric acid, had similar 24-h systolic BP (131.7 mmHg, p = 0.54) and a significantly (p ≤ 0.005) lower 24-h diastolic BP (77.5 vs. 80.9 mmHg) and higher 24-h pulse pressure (54.2 vs. 51.7 mmHg). In similar adjusted analyses, 24-h ambulatory pulse pressure, but not systolic/diastolic BP (p ≥ 0.12), significantly differed across the quartile distributions of urinary sodium excretion (p for trend ≤ 0.04). Further adjusted analyses showed significant (p ≤ 0.04) interaction between serum uric acid and urinary sodium excretion in relation to 24-h systolic BP. In patients with hyperuricaemia (p = 0.04), but not those with normal serum uric acid (p = 0.13), 24-h systolic BP was significantly associated with urinary sodium excretion, with a 6.5 ± 2.1 mmHg difference between quartiles 4 and 1. Similar results were observed for daytime and night-time BP and pulse pressure.

CONCLUSIONS

Both hyperuricaemia and higher dietary sodium intake were associated with higher pulse pressure, and their interaction further heightened systolic BP.

High serum uric acid is associated with increased arterial stiffness in hypertension

Serum uric acid level has been found to be associated with cerebrovascular diseases. However, whether serum uric acid level is a risk factor for arterial stiffness in the hypertension population is unclear. This study was designed to determine the relationship between serum uric acid level and arterial stiffness in the hypertension population. A total of 10450 participants were evaluated for the risk of arterial stiffness. Brachial-ankle pulse wave velocity (baPWV) was assessed, and high baPWV was determined as the highest quartile of baPWV values in a sex-specific manner. We evaluated the association between serum uric acid level and baPWV through multivariate-adjusted linear and logistic regression analyses. There was a significant difference on high baPWV between patients with quartiles of serum uric acid level in females and males (p<0.01), respectively. The odds ratios (95% CI) of the highest baPWV quartile across the sex-specific serum uric acid level were 1.0, 1.71 (1.35, 2.17), 1.75 (1.38, 2.23), and 1.95 (1.51, 2.51) in female, and 1.0, 1.33 (1.09, 1.64), 1.36 (1.11, 1.67), and 1.67 (1.36, 2.04) in male after adjusting for potential confounders. In conclusion, serum uric acid level could be considered as an important risk factor for arterial stiffness in Chinese hypertension population.

Uric acid and cardiometabolic diseases

Hyperuricemia, which has been considered as a cause of gout and nephrolithiasis has recently been suggested to be associated with hypertension, coronary heart disease, heart failure, atrial fibrillation, insulin resistance, and nonalcoholic fatty liver disease. Several clinical and experimental studies have supported uric acid (UA) as an independent risk factor for predicting disease development along with the traditional risk factors. The mechanism by which UA causes cardiometabolic disease has not been fully elucidated to date; however, it has been explained by several hypotheses such as oxidative stress, reduced nitric oxide bioavailability, inflammation, endothelial dysfunction, and so on. Although evidence of the preventive and therapeutic effects of UA lowering therapy on cardiometabolic diseases is still insufficient, it is expected to be considered as a new treatment strategy for such diseases through additional, carefully designed, large-scale clinical studies.

A U-shaped association between serum uric acid with all-cause mortality in normal-weight population

BACKGROUND

It is uncertain how serum uric acid (SUA) associated with all-cause mortality among people with normal weight, hence was explored in this study.

METHODS

We enrolled participants from 1999 to 2006 National Health and Nutrition Examination Survey (NHANES) that had mortality status through 31 December 2015. We estimated adjusted hazard ratios (HRs) and 95% confidence intervals (CI) for all-cause mortality using Cox proportional hazard models, and propensity score analyses were performed. We also performed restricted cubic splines to demonstrate the nonlinear relationship, and used subgroup analysis to examine the effect modification.

RESULTS

We enrolled 6169 participants (2905 men and 3264 women, mean age 42.3 ± 21.4 years) and 1060 (17.2%) cases of all-cause mortality occurred during the mean follow-up of 11.9 years. When using the lowest quartile of SUA as referent, the multivariable HRs for all-cause mortality increased in not parallel with the quartiles of SUA (HRs were 0.92 (95%CI: 0.68, 1.23), 1.10 (95%CI: 0.82, 1.47), and 1.08 (95%CI: 0.80, 1.45) from the second to the fourth quartiles, respectively. When treating SUA as continuous variable, the HRs for all-cause mortality were 1.07 (95%CI: 1.00, 1.15; P = 0.046), 1.03 (95%CI: 0.94, 1.12; P = 0.518) and 1.15 (95%CI: 1.01, 1.31; P = 0.032) in all population, male and female subjects, respectively. Elevated SUA was associated with all-cause mortality and the propensity scores analysis showed the similar results. Subgroup analysis showed SUA was an independent risk of all-cause mortality in female (HR1.17, 95%CI: 1.05, 1.31, P = 0.005), people aged <60 years (HR1.18, 95%CI: 1.03, 1.35, P = 0.018), non-diabetic population (HR1.10, 95%CI: 1.02, 1.18, P = 0.017) and people with eGFR<90 (HR1.10, 95%CI: 1.02, 1.19, P = 0.016). Smoothing spline plots suggested the optimal SUA for the lowest risk of all-cause mortality was approximately 4.7 mg/dl.

CONCLUSION

In normal-weight population, SUA was seemed to be a U-shaped relationship with all-cause mortality.

Hyperuricemia and Cardiovascular Disease

Purine metabolism in the circulatory system yields uric acid as its final oxidation product, which is believed to be linked to the development of gout and kidney stones. Hyperuricemia is closely correlated with cardiovascular disease, metabolic syndrome, and chronic kidney disease, as attested by the epidemiological and empirical research. In this review, we summarize the recent knowledge about hyperuricemia, with a special focus on its physiology, epidemiology, and correlation with cardiovascular disease. This review also discusses the possible positive effects of treatment to reduce urate levels in patients with cardiovascular disease and hyperuricemia, which may lead to an improved clinical treatment plan.

Gender and chronic kidney disease in ankylosing spondylitis: a single-center retrospectively study

BACKGROUND

Ankylosing spondylitis (AS) is a well-known male-predominant inflammatory disease. This study aimed to assess the gender disparity in chronic kidney disease (CKD) in AS patients in China.

METHODS

AS patients were retrospectively studied at Peking Union Medical College hospital between January 2002 and June 2018.

RESULTS

Among 616 patients with AS, 154 (25.0%) patients had CKD (age, 41.8 ± 14.2 years; male:female, 3.2:1). Overall, 80 (13.0%) patients had only microscopic hematuria, 62 (10.1%) had proteinuria with or without hematuria, and 33 (5.4%) exhibited a reduced estimated glomerular filtration rate (eGFR, ≤60 mL/min/1.73 m²). Male CKD patients had more frequent proteinuria (p < 0.01), less microscopic hematuria only (p < 0.01), and lower eGFR (p = 0.04) compared with females. CKD was independently associated with hyperuricemia and total cholesterol in females, and with hyperuricemia, hypertension, and serum albumin in males. After follow-up for 1-7 years, five patients required renal replacement therapy including two patients who were already at stage 5 CKD when enrolled and three patients whose creatinine doubled. One patient died in the male group. No patients in the female group showed progression of renal dysfunction.

CONCLUSIONS

CKD is a common comorbidity in patients with AS. Male patients are more likely to develop severe manifestations compared with female patients. Hyperuricemia was a strong independent risk factor for CKD in both genders, while hypertension and low serum albumin were risk factors for CKD only in males.

Severe Hypouricemia Impairs Endothelium-Dependent Vasodilatation and Reduces Blood Pressure in Healthy Young Men: A Randomized, Placebo-Controlled, and Crossover Study

Background

Uric acid (UA) is a plasmatic antioxidant that has possible effects on blood pressure. The effects of UA on endothelial function are unclear. We hypothesize that endothelial function is not impaired unless significant UA depletion is achieved through selective xanthine oxidase inhibition with febuxostat and recombinant uricase (rasburicase).

Methods and Results

Microvascular hyperemia, induced by iontophoresis of acetylcholine and sodium nitroprusside, and heating‐induced local hyperemia after iontophoresis of saline and a specific nitric oxide synthase inhibitor were assessed by laser Doppler imaging. Blood pressure and renin‐angiotensin system markers were measured, and arterial stiffness was assessed. CRP (C‐reactive protein), allantoin, chlorotyrosine/tyrosine ratio, homocitrulline/lysine ratio, myeloperoxidase activity, malondialdehyde, and interleukin‐8 were used to characterize inflammation and oxidative stress. Seventeen young healthy men were enrolled in a randomized, double‐blind, placebo‐controlled, 3‐way crossover study. The 3 compared conditions were placebo, febuxostat alone, and febuxostat together with rasburicase. The allantoin (μmol/L)/UA (μmol/L) ratio differed between sessions (P<0.0001). During the febuxostat‐rasburicase session, heating‐induced hyperemia became altered in the presence of nitric oxide synthase inhibition; and systolic blood pressure, angiotensin II, and myeloperoxidase activity decreased (P≤0.03 versus febuxostat). The aldosterone concentration decreased in the febuxostat‐rasburicase group (P=0.01). Malondialdehyde increased when UA concentration decreased (both P<0.01 for febuxostat and febuxostat‐rasburicase versus placebo). Other parameters remained unchanged.

Conclusions

A large and short‐term decrease in UA in humans alters heat‐induced endothelium‐dependent microvascular vasodilation, slightly reduces systolic blood pressure through renin‐angiotensin system activity reduction, and markedly reduces myeloperoxidase activity when compared with moderate UA reduction. A moderate or severe hypouricemia leads to an increase in lipid peroxidation through loss of antioxidant capacity of plasma.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT03395977.