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

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

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

Serum Uric Acid Levels Associated with Outcomes of Neurodegenerative Disorders and Brain Health: Findings from the UK Biobank

BACKGROUND

The relationship between serum uric acid (SUA) levels and brain-related health remains uncertain.

OBJECTIVES

This study aimed to investigate the relationship between SUA levels and some neurodegenerative disorders and brain structure.

DESIGN

A longitudinal study.

SETTING AND PARTICIPANTS

384,517 participants who did not have stroke, dementia, and Parkinsonism, with complete urate testes and covariates were included.

MEASUREMENTS

Cox proportional hazards models, competing risk models, and restricted cubic spine models were applied.

RESULTS

During the median follow-up time of 12.7 years (interquartile range [IQR]:12.0, 13.5), 7821 (2.0%) participants developed stroke, 5103 (1.3%) participants developed dementia, and 2341 (0.6%) participants developed Parkinsonism. Nonlinear relationships were identified between SUA levels and stroke (J-shaped), dementia, and Parkinsonism (U-shaped). SUA levels of 4.2 mg/dl, 6.4 mg/dl, and 6.6 mg/dl yielded the lowest risk of stroke, dementia, and Parkinsonism, respectively. Besides, we found high SUA levels reduced the volumes of total brain, grey matter, white matter, grey matter in the hippocampus, and hippocampus, but increased lateral-ventricle volume. Inflammation accounted for 9.1% and 10.0% in the association of SUA with stroke and lateral-ventricle volume.

CONCLUSIONS

Lower SUA levels increased the risk of Parkinsonism, while both lower and higher SUA levels were positively associated with increased risk of stroke and dementia. Moreover, high SUA levels reduced brain structure volumes. Our findings suggest the association between SUA levels and brain-related disorders and highlight the importance of SUA management.

Serum uric acid and high-sensitivity C-reactive protein levels among people living with HIV on dolutegravir and ritonavir-boosted atazanavir-based antiretroviral therapy: a comparative cross-sectional study

Background

After the introduction of antiretroviral therapy, the care given to people living with HIV has become complicated by the appearance of comorbidities as a result of HIV and HAART toxicities, in which cardiovascular disease got the most attention. So, this study aimed to assess serum uric acid and high-sensitivity C-reactive protein levels among people living with HIV on dolutegravir (DTG) and ritonavir-boosted atazanavir (ATV/r)-based therapy.

Methods

An institutional-based comparative cross-sectional study was conducted from November 4, 2021, to January 4, 2022. An equal number of dolutegravir- and ritonavir-boosted atazanavir-treated patients (n = 86 each) were enrolled. A consecutive sampling method was used to select participants. Data were entered into Epidata version 4.6, exported to SPSS version 25.0, and analyzed using Chi-square, Student's t-test, Mann-Whitney U-test, and logistic regression. Statistical significance was set at p < 0.05.

Results

The prevalence of hyperuricemia and high-sensitivity C-reactive protein levels ≥2 mg/L were 46.5% (40/86) and 24.4% (21/86) in the DTG group, and 30.2% (26/86) and 44.2 (38/86) in the ATV/r group, respectively. When compared to ATV/r, a higher mean level of uric acid was found among DTG-based regimens (5.38 mg/dL). Duration of ART (AOR = 2, 95% CI: 1.2, 4.4) and DTG-based regimen (AOR = 1.9, 95% CI: 1.04, 3.8) were significant predictors of developing hyperuricemia. ATV/r-based regimen (AOR = 3, 95% CI: 1.5, 8.3) and high waist circumference (AOR = 2.5, 95% CI: 1, 3.5) were significantly associated with increased high-sensitivity C-reactive protein levels.

Conclusion

It is observed that DTG-based and ATV/r-based ART are associated with hyperuricemia and increased high-sensitivity C-reactive protein levels, respectively. Therefore, it is important to consider and evaluate serum uric acid and high-sensitivity C-reactive protein levels in patients taking DTG and ATV/r-based ART, as well as among those on HAART for years and with a higher waist circumference, so as to detect and prevent early the risk of having CVD.

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.

Serum Uric Acid, Hypertriglyceridemia, and Carotid Plaques: A Sub-Analysis of the URic Acid Right for Heart Health (URRAH) Study

High levels of serum uric acid (SUA) and triglycerides (TG) might promote high-cardiovascular-risk phenotypes, including subclinical atherosclerosis. An interaction between plaques xanthine oxidase (XO) expression, SUA, and HDL-C has been recently postulated. Subjects from the URic acid Right for heArt Health (URRAH) study with carotid ultrasound and without previous cardiovascular diseases (CVD) (n = 6209), followed over 20 years, were included in the analysis. Hypertriglyceridemia (hTG) was defined as TG ≥ 150 mg/dL. Higher levels of SUA (hSUA) were defined as ≥5.6 mg/dL in men and 5.1 mg/dL in women. A carotid plaque was identified in 1742 subjects (28%). SUA and TG predicted carotid plaque (HR 1.09 [1.04-1.27], p < 0.001 and HR 1.25 [1.09-1.45], p < 0.001) in the whole population, independently of age, sex, diabetes, systolic blood pressure, HDL and LDL cholesterol and treatment. Four different groups were identified (normal SUA and TG, hSUA and normal TG, normal SUA and hTG, hSUA and hTG). The prevalence of plaque was progressively greater in subjects with normal SUA and TG (23%), hSUA and normal TG (31%), normal SUA and hTG (34%), and hSUA and hTG (38%) (Chi-square, 0.0001). Logistic regression analysis showed that hSUA and normal TG [HR 1.159 (1.002 to 1.341); p = 0.001], normal SUA and hTG [HR 1.305 (1.057 to 1.611); p = 0.001], and the combination of hUA and hTG [HR 1.539 (1.274 to 1.859); p = 0.001] were associated with a higher risk of plaque. Our findings demonstrate that SUA is independently associated with the presence of carotid plaque and suggest that the combination of hyperuricemia and hypertriglyceridemia is a stronger determinant of carotid plaque than hSUA or hTG taken as single risk factors. The association between SUA and CVD events may be explained in part by a direct association of UA with carotid plaques.

Association of serum uric acid level with intracranial aneurysms: A Mendelian randomization study

Objective

Numerous studies have posited the involvement of serum uric acid (SUA) in the pathogenesis and progression of various cardiovascular diseases, particularly aortic aneurysms. However, the casual effect of SUA level on intracranial aneurysms (IAs) was rarely studied. Consequently, we aimed to explore the causal association between SUA and IAs using Mendelian randomization (MR) analysis.

Methods

We conducted a two-sample MR analysis with SUA as the exposure variable and IAs as the outcome variable. Genome-wide association study (GWAS) datasets for SUA were acquired from the Open GWAS catalog, including 389,404 European and 129,405 East Asian individuals. The dataset for IAs was sourced from a meta-analysis of GWASs comprising 317,636 individuals across different ancestral populations (European: 7495 cases and 71,934 controls; East Asian: 3259 cases and 234,948 controls). The MR analyses were performed according to populations (European and East Asian) and IAs status [unruptured IAs (uIAs) or aneurysmal subarachnoid hemorrhage (aSAH)], respectively. The inverse variance weighted (IVW) method was employed as primary analysis to discern causal estimates.

Results

Our findings revealed that an elevated genetically predicted SUA level (mg/dL) correlated with an increased risk of IAs among the European population (OR = 1.29 [95%CI:1.05-1.57], P = 0.013) and East Asian population (OR = 1.56 [95%CI: 1.27-1.92], P < 0.001). Among European individuals, subgroup analysis indicated a persistent causal association of SUA with uIAs (OR = 1.50 [95%CI: 1.08-2.08], P = 0.015) and aSAH (OR = 1.26 [95%CI: 1.00-1.60], P = 0.049). However, subgroup analysis in East Asian populations was not conducted due to the lack of separate data on uIAs and aSAH.

Conclusions

Our MR analysis demonstrated a causal relationship between elevated SUA levels and an amplified risk of IAs. Further rigorous investigations are imperative to provide evidence and elucidate the underlying mechanisms.

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

BACKGROUND AND AIM

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Associations between carotid plaque shape, biomechanical parameters, and ischemic stroke in mild carotid stenosis with a single plaque

PURPOSE

This cross-sectional cohort-comparison observational study investigated the value of high-frame-rate vector flow (V Flow) imaging for evaluating differences in carotid plaque shape and biomechanical parameters in patients with mild stenosis according to a recent history of ipsilateral ischemic stroke.

METHODS

The present study included 352 patients from February 2023 to October 2023, who were categorized as symptomatic or asymptomatic based on a history of recent ischemic stroke and ipsilateral ischemic lesions detected on head computed tomography or magnetic resonance imaging. A Mindray Resona R9 system was used for B-mode ultrasonography and V Flow imaging. The upstream and downstream surfaces of the plaques were examined at the carotid bifurcation for wall shear stress (WSS), oscillatory shear index (OSI), and turbulence index, which performed peri-plaque biomechanical condition. Multivariable logistic regression models were used to determine associations between plaque shape, V Flow parameters, and ischemic stroke.

RESULTS

Symptomatic patients exhibited higher WSS values for the upstream and downstream surfaces of carotid plaque, as well as higher OSI and turbulence index values for the downstream surface. Type Ⅲ plaques and higher WSS and OSI values for the downstream surface of the plaque were significantly associated with ischemic stroke. Type Ⅲ plaques were more prevalent in symptomatic patients and demonstrated much higher WSS and OSI values for the downstream plaque surface in both groups.

CONCLUSION

High-frame-rate V Flow imaging could assess peri-plaque biomechanical forces and may provide effective imaging biomarkers for early prediction of ischemic stroke in patients with mild stenosis.

Dysuricemia

Gout results from elevated serum urate (SU) levels, or hyperuricemia, and is a globally widespread and increasingly burdensome disease. Recent studies have illuminated the pathophysiology of gout/hyperuricemia and its epidemiology, diagnosis, treatment, and complications. The genetic involvement of urate transporters and enzymes is also proven. URAT1, a molecular therapeutic target for gout/hyperuricemia, was initially derived from research into hereditary renal hypouricemia (RHUC). RHUC is often accompanied by complications such as exercise-induced acute kidney injury, which indicates the key physiological role of uric acid. Several studies have also revealed its physiological role as both an anti-oxidant and a pro-oxidant, acting as both a scavenger and a generator of reactive oxygen species (ROSs). These discoveries have prompted research interest in SU and xanthine oxidoreductase (XOR), an enzyme that produces both urate and ROSs, as status or progression biomarkers of chronic kidney disease and cardiovascular disease. The notion of "the lower, the better" is therefore incorrect; a better understanding of uric acid handling and metabolism/transport comes from an awareness that excessively high and low levels both cause problems. We summarize here the current body of evidence, demonstrate that uric acid is much more than a metabolic waste product, and finally propose the novel disease concept of "dysuricemia" on the path toward "normouricemia", or optimal SU level, to take advantage of the dual roles of uric acid. Our proposal should help to interpret the spectrum from hypouricemia to hyperuricemia/gout as a single disease category.

Scientific Landscape of Oxidative Stress in Stroke: From a Bibliometric Analysis to an in-Depth Review

Stroke is an acute cerebrovascular disease resulting from either obstruction or rupture of a blood vessel in the brain. Oxidative stress (OS), referred to a status where cellular oxidative capacities overwhelm antioxidative defenses, is involved in the pathophysiology of stroke. The bibliometric analysis and in-depth review aim to depict the research trend of OS in stroke. Relevant scientific publications were acquired from the Web of Science Core Collection database. Scientific landscape of OS in stroke was illustrated by general quantitative trend, impactful journals, and co-authorship of various academic units (i.e., countries/regions, organizations, and authors). Furthermore, theme analysis predicting the hot research issues and frontiers was performed. 15,826 documents regarding OS in stroke were obtained over a time span of more than 20 years from 1992 to 2021. The overall tendency of publication counts was continuously on the rise. Bibliometric analysis indicated China and the United States were predominant in this study field, as reflected by their high publication counts and intensive collaboration with other countries. Current key research areas of OS in stroke may lie in the investigation of neuroinflammation, and interaction among multiple cell death mechanisms including apoptosis, autophagy, and ferroptosis to search for effective treatments. Moreover, another hot topic could be the association between air pollution and stroke, and its underlying mechanisms. As the exploration of OS in stroke is speculated to be a continuous hot spot in the future, this article may be helpful for researchers to conduct future studies with the understanding of influential academic forces and research highlights.

Progress on Physical Field-Regulated Micro/Nanomotors for Cardiovascular and Cerebrovascular Disease Treatment

Cardiovascular and cerebrovascular diseases (CCVDs) are two major vasculature-related diseases that seriously affect public health worldwide, which can cause serious death and disability. Lack of targeting effect of the traditional CCVD treatment drugs may damage other tissues and organs, thus more specific methods are needed to solve this dilemma. Micro/nanomotors are new materials that can convert external energy into driving force for autonomous movement, which can not only enhance the penetration depth and retention rates, but also increase the contact areas with the lesion sites (such as thrombus and inflammation sites of blood vessels). Physical field-regulated micro/nanomotors using the physical energy sources with deep tissue penetration and controllable performance, such as magnetic field, light, and ultrasound, etc. are considered as the emerging patient-friendly and effective therapeutic tools to overcome the limitations of conventional CCVD treatments. Recent efforts have suggested that physical field-regulated micro/nanomotors on CCVD treatments could simultaneously provide efficient therapeutic effect and intelligent control. In this review, various physical field-driven micro/nanomotors are mainly introduced and their latest advances for CCVDs are highlighted. Last, the remaining challenges and future perspectives regarding the physical field-regulated micro/nanomotors for CCVD treatments are discussed and outlined.

The fructose survival hypothesis for obesity

The fructose survival hypothesis proposes that obesity and metabolic disorders may have developed from over-stimulation of an evolutionary-based biologic response (survival switch) that aims to protect animals in advance of crisis. The response is characterized by hunger, thirst, foraging, weight gain, fat accumulation, insulin resistance, systemic inflammation and increased blood pressure. The process is initiated by the ingestion of fructose or by stimulating endogenous fructose production via the polyol pathway. Unlike other nutrients, fructose reduces the active energy (adenosine triphosphate) in the cell, while blocking its regeneration from fat stores. This is mediated by intracellular uric acid, mitochondrial oxidative stress, the inhibition of AMP kinase and stimulation of vasopressin. Mitochondrial oxidative phosphorylation is suppressed, and glycolysis stimulated. While this response is aimed to be modest and short-lived, the response in humans is exaggerated due to gain of 'thrifty genes' coupled with a western diet rich in foods that contain or generate fructose. We propose excessive fructose metabolism not only explains obesity but the epidemics of diabetes, hypertension, non-alcoholic fatty liver disease, obesity-associated cancers, vascular and Alzheimer's dementia, and even ageing. Moreover, the hypothesis unites current hypotheses on obesity. Reducing activation and/or blocking this pathway and stimulating mitochondrial regeneration may benefit health-span. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part I)'.

High Uric Acid Promotes Atherosclerotic Plaque Instability by Apoptosis Targeted Autophagy

AIMS

Acute rupture or erosion of unstable atherosclerotic plaques is a major cause of adverse consequences of atherosclerotic cardiovascular disease, often leading to myocardial infarction or stroke. High uric acid (HUA) is associated with the increasing risk of cardiovascular events and death. However, the mechanism by which HUA promotes atherosclerosis and whether HUA affects plaque stability are still unclear.

METHODS

We constructed an atherosclerotic Apoe-/- mouse model with HUA. The progression of atherosclerosis and plaques was determined by Oil Red O staining, hematoxylin and eosin (H&E) staining, and Masson staining. TdT-mediated dUTP nick-end labeling assay and immunohistochemistry were used to observe the changes of apoptosis and autophagy in plaques, respectively. Then, we validated the in vivo results with RAW 264.7 cell line.

RESULTS

HUA promoted atherosclerosis and exacerbated plaque vulnerability, including significantly increased macrophage infiltration, lipid accumulation, enlarged necrotic cores, and decreased collagen fibers. HUA increased cell apoptosis and inhibited autophagy in plaques. In vitro results showed that HUA decreased cell viability and increased cell apoptosis in foam cells macrophages treated with oxidized low-density lipoprotein. An activator of autophagy, rapamycin, can partially reverse the increasing apoptosis.

CONCLUSION

HUA promoted atherosclerosis and exacerbated plaque vulnerability, and HUA facilitates foam cell apoptosis by inhibiting autophagy.

Purine-ifying uric acid by gut microbes

Elevated bloodstream levels of uric acid, a mammalian purine degradation product, are associated with several noncommunicable diseases. Recent studies by Kasahara et al. and Liu et al. define purine-degrading activities of the gut microbiota that lower bloodstream uric acid in atherosclerosis and gout disease models, establishing a novel microbial role in host health.

Serum Urate Levels and Ultrasound Characteristics of Carotid Atherosclerosis across Obesity Phenotypes

BACKGROUND

Existing evidence suggests a close link among high levels of serum urate (SU), obesity and carotid atherosclerosis. The aim of the present study was to evaluate the interrelations between SU levels and carotid atherosclerosis in subjects with different obesity phenotypes.

METHODS

In this study, a total of 2076 subjects (mean age 48.1 ± 13.1 years; 1307 women) were recruited: 59 with general obesity, 616 with central obesity, 715 with mixed (general-central) obesity and 686 non-obese. Anthropometric measurements, vascular risk factors, blood biochemistry analysis (including SU levels), and carotid ultrasound were performed. Ultrasound assessment included evaluation of intima-media thickness (IMT) and plaque characteristics, including number, total area and type (vulnerable vs. stable) of plaques.

RESULTS

After adjustment for potential confounders, the highest levels of SU were observed in subjects with mixed obesity, followed by subjects with central obesity, general obesity and the non-obese (309.4 ± 82.2 vs. 301.2 ± 73.1 vs. 272.9 ± 61.8 vs. 234.2 ± 59.8 μmol/L, respectively; F = 149.2, post hoc p < 0.001). Similarly, subjects with mixed and central obesity presented higher values of IMT compared to subjects with general obesity and the non-obese (0.68 ± 0.16 vs. 0.67 ± 0.16 vs. 0.62 ± 0.14 vs. 0.57 ± 0.13 mm, respectively; F = 54.2, post hoc p < 0.001). No difference in number, total area and type of plaques among obesity groups were attested (all p > 0.05). Significantly higher IMT values were observed in subjects with increased SU levels compared to subjects with normal SU levels (0.70 ± 0.10 vs. 0.62 ± 0.14 mm, p = 0.02) only within the central obesity group. Increasing levels of SU were associated with a higher frequency of increased IMT only in subjects with central obesity (OR 1.033, 95% CI 1.025-1.041). Similarly, SU levels yielded a satisfactory performance in detecting subjects with increased IMT (AUC 0.65, 95% CI 0.50-0.73, subjects with carotid plaques (0.62, 95% CI 0.55-0.68) and subjects with vulnerable plaque types (0.68, 0.59-0.76) only within the central obesity group.

CONCLUSIONS

Among the studied obesity types, the association between SU levels and markers of carotid atherosclerosis was of particular significance in subjects with central obesity.

Serum uric acid variation and the risk of cardiovascular disease: A prospective cohort study

BACKGROUND

The association of serum uric acid (SUA) with cardiovascular disease (CVD) is inconsistent and limited by a single measurement of SUA. This study aimed to investigate the association of SUA variation, considering its magnitude and direction, with the risk of CVD.

METHODS

This study included 41,578 participants with four biennial measurements of SUA during 2006-2012 from the Kailuan study. SUA variation was measured using the coefficient of variation (primary index), standard deviation, average real variability, and variability independent of mean, and the direction of variation was also assessed. Multivariate-adjusted Cox regressions were used to assess the associations, and Bayesian network was utilized to find the most important pathway from SUA variation to CVD.

RESULTS

During a median follow-up of 6.74 (interquartile range: 6.45-7.03) years, we identified 1,852 (4.45%) cases of incident CVD. A large SUA variation (top vs. bottom tertiles) was associated with a higher risk of CVD (hazard ratio [HR], 1.24; 95% confidence interval [CI], 1.11-1.40), especially in older adults than that in young adults (Pint=0.0137). The higher risk of CVD was observed with both large rises (HR, 1.24; 95% CI, 1.10-1.39) and falls (HR, 1.19; 95% CI, 1.03-1.38) in SUA variation. The hazardous effect of SUA variation on CVD was mainly induced by excessive inflammation and elevated blood pressure. Similar results were observed for CVD subtypes.

CONCLUSIONS

Elevated SUA variation was associated with a higher risk of CVD, irrespective of the direction of SUA variation, and inflammation played an important role in the pathway.

Serum Uric Acid Levels Are Associated with the Echogenic Features of Carotid Plaque Vulnerability in Elderly Patients with Atherosclerotic Disease

Uric acid is a marker of inflammation and a risk factor for atherosclerosis that has been suggested to play a role in carotid plaque instability. Reduced atherosclerotic plaque echogenicity at ultrasound examination is associated with alarming histopathological features and inflammation. In this study, we investigated the relationship between serum uric acid (SUA) levels and echogenic patterns of plaque instability in elderly subjects with carotid atherosclerosis. Since uric acid metabolism largely depends on renal function, SUA levels were indexed for serum creatinine levels (SUA/SCr). We enrolled 108 patients aged 65 years or more (72.7 ± 5.9 years; 50 females and 58 males) who underwent carotid duplex ultrasound to evaluate plaque echogenicity by greyscale median (GSM). The regression analysis demonstrated a significant inverse association between the GSM and the SUA/SCr ratio (β: -0.567; 95% CI -0.751 to -0.384 and p < 0.0001). Stepwise multivariate regression showed that the SUA/SCr ratio explained 30.3% of GSM variability (β: -0.600; 95% CI -0.777/-0.424, p < 0.0001, and semi-partial correlation 0.303). After a mean period of 3.5 ± 0.5 years, 48 patients were reevaluated according to the same baseline study protocol. The regression analysis demonstrated a still significant inverse association between the GSM and the SUA/SCr ratio (β: -0.462; 95% CI -0.745 to -0.178 and p = 0.002). Stepwise multivariate regression showed that the SUA/SCr ratio explained 28.0% of GSM variability (coefficient -0.584, 95% CI -0.848/-0.319, p < 0.0001, and semi-partial R² 0.280). In conclusion, this study demonstrates that SUA levels indexed for serum creatinine are associated with the echogenic features of carotid plaque vulnerability in elderly patients with atherosclerotic disease. These data could suggest an influential role for uric acid metabolism in carotid plaque biology.

Urate-lowering therapy following a treat-to-target continuation strategy compared to a treat-to-avoid-symptoms discontinuation strategy in gout patients in remission (GO TEST Finale): study protocol of a multicentre pragmatic randomized superiority trial

BACKGROUND

Long-term gout treatment is based on reducing serum urate levels using urate-lowering therapy (ULT). Most guidelines recommend using a lifelong continuation treat-to-target (T2T) strategy, in which ULT is dosed or combined until a serum urate target has been reached and maintained. However, a frequently used alternative strategy in clinical practice is a treat-to-avoid-symptoms (T2S) ULT discontinuation strategy, with the possibility of restarting the medication. This latter strategy aims at an acceptable symptom state, regardless of serum urate levels. High-quality evidence to support either strategy for patients in prolonged remission while using ULT is lacking.

METHODS

We developed an investigator-driven pragmatic, open-label, multicentre, randomized, superiority treatment strategy trial (GO TEST Finale). At least 278 gout patients using ULT who are in remission (>12 months, preliminary gout remission criteria) will be randomized 1:1 to a continued T2T strategy (treatment target serum urate < 0.36 mmol/l) or switched to a T2S discontinuation strategy in which ULT is tapered to stop and restarted in case of (persistent or recurrent) flaring. The primary outcome is the between-group difference in the proportion of patients not in remission during the last 6 months of 24 months follow-up and will be analyzed using a two proportion z test. Secondary outcomes are group differences in gout flare incidence, reintroduction or adaptation of ULT, use of anti-inflammatory drugs, serum urate changes, occurrence of adverse events (with a special interest in cardiovascular and renal events), and cost-effectiveness.

DISCUSSION

This study will be the first clinical trial comparing two ULT treatment strategies in patients with gout in remission. It will contribute to more specific and unambiguous guideline recommendations and improved cost-effectiveness of long-term gout treatment. It also paves the way (exploratory) to individualized long-term ULT treatment. In this article, we elaborate on some of our trial design choices and their clinical and methodological consequences.

TRIAL REGISTRATION

International Clinical Trial Registry Platform (ICTRP) NL9245. Registered on 2 February 2021 (METC Oost-Nederland NL74350.091.20); EudraCT EUCTR2020-005730-15-NL. Registered on 11 January 2021.

A new application of papain: As a peroxidase-like catalyst for fluorometric detection of uric acid

Papain, as a classical cysteine protease, has been widely used in the food, pharmaceutical, chemical, and cosmetic fields. However, there are few information about the peroxidase-like activity of papain catalyzed substrate to produce fluorescence. In this study, we found that papain can catalyze H₂O₂ to convert o-phenylenediamine (OPD), and generate fluorescence emission at 550 nm under 430 nm excitation. Based on this foundation, we report a papain/OPD/H₂O₂ system for fluorescence detection of uric acid. The method exhibits a wide linear range of 10-1000 μM with a limit-of-detection of 4.6 μM, and has been successfully used to detect uric acid in human serum. This study paves the way for the application of papain as catalyst for fluorescence detection of different target biomolecules, such as cholesterol, glucose, lactate, for which H₂O₂ is a product of oxidoreductase enzymes.

Platinum nanoparticles confined in metal-organic frameworks as excellent peroxidase-like nanozymes for detection of uric acid

High levels of uric acid (UA) in humans can cause a range of diseases, and traditional assays that rely on uric acid enzymes to break down uric acid are limited by the inherent deficiencies of natural enzymes. Fortunately, the rapid development of nanozymes in recent years is expected to solve the above-mentioned problems. Hence, we used a host-guest strategy to synthesize a platinum nanoparticle confined in a metal-organic framework (Pt NPs@ZIF) that can sensitively detect UA levels in human serum. Unlike previously reported free radical-catalyzed oxidation systems, its unique electron transfer mechanism confers excellent peroxidase-like activity to Pt NPs@ZIF. In addition, UA can selectively inhibit the chromogenic reaction of TMB, thus reducing the absorbance of the system. Therefore, using the peroxidase-like activity of Pt NPs@ZIF and using TMB as a chromogenic substrate, UA can be detected directly without relying on natural enzymes. The results showed a relatively wide detection range (10-1000 μM) and a low detection limit (0.2 μM). Satisfactory results were also obtained for UA in human serum. This study with simple operation and rapid detection offers a promising method for efficiently detecting UA in serum.

Uric Acid and Chronic Kidney Disease: Still More to Do

Gout and hyperuricemia are present in 25% and 60% of patients with chronic kidney disease (CKD), respectively. Despite the common association, the role of uric acid in the progression of kidney disease and in metabolic complications remains contested. Some authorities argue that the treatment of asymptomatic hyperuricemia in CKD is not indicated, and some have even suggested hyperuricemia may be beneficial. Here, we review the various arguments both for and against treatment. The weight of the evidence suggests asymptomatic hyperuricemia is likely injurious, but it may primarily relate to subgroups, those who have systemic crystal deposits, those with frequent urinary crystalluria or kidney stones, and those with high intracellular uric acid levels. We recommend carefully designed clinical trials to test if lowering uric acid in hyperuricemic subjects with cardiometabolic complications is protective.