Hyperuricemia, gout, and cardiovascular disease: an update

Polysaccharides from Alpinia oxyphylla fruit prevent hyperuricemia by inhibiting uric acid synthesis, modulating intestinal flora and reducing renal inflammation

Hyperuricemia (HUA) is one of the most common chronic diseases today, with a prevalence exceeding 14 % in both the United States and China. Current clinical treatments for HUA focus on promoting uric acid (UA) excretion and inhibiting UA production, but often neglect the strain on the liver and kidneys. The fruit of Alpinia oxyphylla (A. oxyphylla) is known to improve renal function, regulate metabolism, and exhibit anti-inflammatory effects; however, its effectiveness and mechanisms in treating HUA are not well understood. In this study, HUA mice induced by potassium oxonate and adenine were treated with A. oxyphylla polysaccharide (AFP) for 21 days. The levels associated with HUA were quantified using assay kits to evaluate the impact of AFP on HUA. Serum metabolomics and 16S rRNA sequencing were used to investigate the mechanisms by which AFP ameliorates HUA. The results showed that AFP treatment reduced abnormal biochemical levels, including UA, blood urea nitrogen, and creatinine, in HUA mice. AFP inhibited UA synthesis by regulating pyrimidine metabolism and the metabolism of alanine, aspartate and glutamate, reduced kidney inflammation, and promoted UA excretion by regulating intestinal flora. Thus, AFP appears to be an effective agent for alleviating HUA symptoms.

Diagnosis of Gout as a Correlative Risk for Acute Myocardial Infarction in the Absence of Traditional Cardiovascular Risk Factors

OBJECTIVES

We aimed to study the impact of gout as a correlative risk factor in the incidence of acute myocardial infarction (AMI) among patients without known MI risk factors. Our study population was obtained from the National Inpatient Sample (NIS) 2011-2018 using the International Classification of Diseases, Ninth and Tenth Revisions.

METHODS

This study included patients without cardiovascular disease (CVD), and various outcomes were compared among patients with and without gout. Cohorts were weighted using an algorithm provided by the NIS, which allows for national estimates. Our primary endpoint was the odds of developing an MI, and secondary endpoints were adverse hospital events and length of stay. In total, 117,261,842 patients without CVD risk factors were included in this study, 187,619 (0.16%) of whom had a diagnosis of gout.

RESULTS

Patients without CVD risk factors who had gout were older and more likely to be male compared with patients without gout. Among patients without CVD risk factors, the odds of having an AMI were significantly higher in those with gout compared with those without, even after adjusting for chronic nonsteroidal anti-inflammatory drug and oral steroid use. Moreover, patients without CVD risk factors and with gout were more likely to develop acute renal failure, acute thromboembolic event, shock, acute gastrointestinal bleed, and arrhythmia compared with those without gout. Furthermore, patients without CVD risk factors who were admitted with gout had higher mortality compared with those without gout.

CONCLUSIONS

In our study, we found that patients without risk factors for AMI who had gout were more likely to develop AMI compared with those without gout. Furthermore, the same patients were more likely to develop other adverse outcomes. Even with proper management, these individuals should be monitored closely for coronary events.

Single-cell calcium monitoring of Caco-2 cell co-cultured with intestinal microbiome through carbon fiber based potentiometric microelectrode

The Caco-2 cells were used as intestinal epithelial cell model to illustrate the hyperuricemia (HUA) mechanism under the co-culture of the imbalanced intestinal microbiome in this work. The uric acid (UA) concentration in the HUA process was monitored, and could be up to 425 μmol/L at 8 h co-cultured with the imbalanced intestinal microbiome. Single-cell potentiometry based on ion-selective microelectrode was used to study extracellular calcium change, which is hypothesized to play an important role in the UA excretion. The potential signal of the calcium in the extremely limited microenvironment around single Caco-2 cell was recorded through the single-cell analysis platform. The potential signal of sharp decrease and slow increase followed within a few seconds indicates the sudden uptake and gradually excretion process of calcium through the cell membrane. Moreover, the value of the potential decrease increases with the increase of the time co-cultured with the imbalanced intestinal microbiome ranging from 0 to 8 h. The Ca2+ concentration around the cell membrane could decrease from 1.3 mM to 0.4 mM according to the potential decrease of 27.0 mV at the co-culture time of 8 h. The apoptosis ratio of the Caco-2 cells also exhibits time dependent with the co-culture of the imbalanced intestinal microbiome, and was 39.1 ± 3.6 % at the co-culture time of 8 h, which is much higher than the Caco-2 cells without any treatment (3.9 ± 2.9 %). These results firstly provide the links between the UA excretion with the apoptosis of the intestinal epithelial cell under the interaction of the imbalanced intestinal microbiome. Moreover, the apoptosis could be triggered by the calcium signaling.

Whey protein peptides PEW and LLW synergistically ameliorate hyperuricemia and modulate gut microbiota in potassium oxonate and hypoxanthine-induced hyperuricemic rats

Pro-Glu-Trp (PEW) and Leu-Leu-Trp (LLW) are peptides derived from whey protein digestive products; both peptides exhibit xanthine oxidase inhibitory activity in vitro. However, it remains unclear whether these peptides can alleviate hyperuricemia (HUA) in vivo. In this study, we investigated the roles of PEW and LLW, both individually and in combination, in alleviating HUA induced by potassium oxonate and hypoxanthine. Together, PEW and LLW exhibited synergistic effects in reducing the serum levels of uric acid (UA), creatinine, and blood urea nitrogen, as well as increasing the fractional excretion of UA. The combined treatment with PEW and LLW inhibited UA synthesis, promoted UA excretion, and restored renal oxidative stress and mitochondrial damage. Moreover, the combined treatment alleviated dysbiosis of the gut microbiota, characterized by increased helpful microbial abundance, decreased harmful bacterial abundance, and increased production of short-chain fatty acids. Taken together, these results indicate that the combination of PEW and LLW mitigate HUA and kidney injury by rebalancing UA synthesis and excretion, modulating gut microbiota composition, and improving oxidative stress.

Higher ratio of serum uric acid to serum creatinine (SUA/SCr) increases the risk of metabolic unhealthy phenotype

BACKGROUND AND AIM

It is very important to understand which factors play roles in switching from a healthy to an unhealthy metabolism. It is unclear if SUA/SCr is an independent risk factor for metabolic unhealthy phenotype. We examined whether SUA/SCr is associated with an increased risk for metabolic unhealthy phenotype in the Chinese population.

METHODS AND RESULTS

As many as 3158 subjects aged 25-75 years who had a metabolic healthy phenotype at baseline were included in the retrospective cohort study. They were assigned to four groups based on the quartile of SUA/SCr. We compared the demographic and clinical characteristics among the four groups. The correlation between SUA/SCr and the risk of metabolic unhealthy phenotype in the overall population and stratified by subgroups was examined by logistic regression analyses. Greater SUA/SCr values were correlated with greater BMI, systolic and diastolic BP, TC, TG, RBC, WBC, HB, ALT, SUA and eGFR. During the two-year follow-up, 632 of the study subjects (20.01%) developed new-onset metabolic unhealthy phenotype from the total of 3158 study subjects. A statistically significant increase in the rates of metabolic unhealthy phenotype was observed with increasing SUA/SCr levels within each group. After multivariate adjustment, the adjusted ORs and 95% CIs were 1.44 (1.03-2.00) and 2.11 (1.52-2.94) in the Q3 group and Q4 group, respectively.

CONCLUSION

SUA/SCr was positively related to the risk of metabolic unhealthy phenotype in the Chinese subjects, suggesting the potential of SUA/SCr to serve as an independent risk predictor in the development of metabolic unhealthy phenotype.

Association of serum uric acid to lymphocyte ratio, a novel inflammatory biomarker, with risk of stroke: A prospective cohort study

MAIN PROBLEM

Inflammation plays an important role in the pathological progress associated with stroke. Serum uric acid (SUA) to lymphocyte ratio (ULR), a novel inflammatory biomarker, has been considered as a better risk stratification tool of adverse outcomes than SUA or lymphocyte alone. This study aimed to investigate whether ULR produced more predictive value for stroke and explore the potential mediators of the associations.

METHODS

This study enrolled 93,023 Chinese participants without stroke and myocardial infarction at baseline. Cox proportional hazard models were used to analyze the associations of ULR with stroke and subtypes. Mediation analyses were conducted to explore potential mediators of the associations.

RESULTS

During a median follow-up of 13.00 years, 6081 cases of incident stroke occurred, including 5048 cases of ischemic stroke (IS) and 900 cases of hemorrhagic stroke (HS). After adjustment for confounders, the Q4 group was associated with a higher risk of HS (HR, 1.25; 95% CI, 1.03-1.50), but not with total stroke (HR, 1.07; 95% CI, 1.03-1.13) or IS (HR, 1.04; 95% CI, 0.97-1.12). No significant associations were found between SUA or lymphocyte and any stroke. ULR outperformed SUA or lymphocytes alone in predicting stroke. Additionally, the significant association between ULR and HS was partially mediated by systolic blood pressure (20.32%), diastolic blood pressure (11.18%) and estimated glomerular filtration rate (9.19%).

CONCLUSIONS

ULR was significantly associated with the risk of HS, but not with IS. Systolic blood pressure, diastolic blood pressure and estimated glomerular filtration rate were potential mediators for the association.

Global burden of gout in 1990-2019: A systematic analysis of the Global Burden of Disease study 2019

BACKGROUND AND AIMS

Although gout is one of the most common rheumatic diseases, world data are lacking because most studies have focused on industrialized countries. Therefore, we aimed to investigate the global burden of gout and its associations with the year of diagnosis, age, geographical region, sociodemographic status and various further risk factors.

METHODS

Retrospective data from the Global Burden of Disease (GBD) were used, initially collected between 1990 and 2019. Raw numbers and age-standardized rates (per 100,000 persons) of prevalence, incidence and years lived with disability (YLDs) of gout were extracted from GBD 2019 for 204 countries and territories and stratified by sex, age, year, sociodemographic index and geographic region. Correlations between gout and other chronic diseases were identified, and the burden attributable to high body mass index (BMI) and kidney dysfunction was described.

RESULTS

The total number of patients and gout age-standardized prevalence rate increased between 1990 and 2019. Gout was most prevalent in Australasia and high-income North America, and a higher sociodemographic index (SDI) was associated with higher age-standardized prevalence, incidence and YLDs. High BMI and kidney dysfunction were risk factors for gout, while gout was correlated with other kidney diseases.

CONCLUSIONS

The global prevalence of gout, as well as incidence, and YLDs increased worldwide from 1990 to 2019 and had a significant association with sex, age, geographic region, SDI and risk factors. Understanding the complex interplay of environmental, sociodemographic and geographic risk factors is essential in mitigating the ever-rising disease burden of gout.

Hypouricemic and nephroprotective effects of palmatine from Cortex Phellodendri Amurensis: A uric acid modulator targeting Keap1-Nrf2/NLRP3 axis

ETHNOPHARMACOLOGICAL RELEVANCE

Palmatine (Pal) is a major bioactive alkaloid originated from ancient Chinese herbal medicine Cortex Phellodendri Amurensis (CPA), which has long been applied to treat hyperuricemia (HUA)-related diseases. Pal possesses potent anti-inflammatory and anti-oxidant effects against metabolic diseases. However, its potential beneficial effect against PO (potassium oxonate)/HX (hypoxanthine)-induced HUA remains elusive.

AIM OF THE STUDY

This study aimed to investigate the potential pharmacological effect and mechanism of Pal on PO/HX-induced HUA in mice.

MATERIAL AND METHODS

A mouse model of HUA was established by co-administration of PO/HX once daily for 7 consecutive days. The HUA mice were orally given three doses (25, 50 and 100 mg/kg) of Pal daily for a week. Febuxostat (Feb, 5 mg/kg) was given as a positive control. At the scheduled termination of the experiment, the whole blood, liver and kidney were collected for subsequent analyses. The concentrations of uric acid (UA), creatinine (CRE) and blood urea nitrogen (BUN), and activities of adenosine deaminase (ADA) and xanthine oxidase (XOD) were evaluated. Histopathological alterations of the kidney were detected by H&E staining. The inflammatory and oxidative stress status was detected by assay kits. Additionally, key proteins involved in the urate transporter, Keap1-Nrf2 and TXNIP/NLRP3 signaling pathways were evaluated by immunohistochemistry and Western blotting. Finally, molecular docking was employed to probe the binding characteristics of Pal and target proteins Keap1, NLRP3, URAT1 and HO-1.

RESULTS

Administration of Pal substantially decreased the elevated kidney weight, lowered UA, CRE and BUN levels, and attenuated abnormal histopathological alterations. Meanwhile, treatment with Pal also dramatically lowered hepatic XOD and ADA activities. Besides, Pal treatment effectively mitigated the renal inflammatory and oxidative stress markers. Further mechanistic investigation indicated Pal distinctly downregulated the protein levels of GLUT9 and URAT1, while up-regulated the expression levels of OAT1 and ABCG2. Pal also restored Nrf2 activation, promoted subsequent expression of anti-oxidative enzymes, and downregulated the expressions of TXNIP, NLRP3, apoptosis-associated speck-like (ASC), caspase-1, IL-1β and IL-18. Molecular docking analysis also indicated Pal firmly bound with Keap1, NLRP3, URAT1 and HO-1.

CONCLUSIONS

These findings indicated that Pal exhibited favorable anti-HUA effect via modulating the expressions of transporter-related proteins and suppressing XOD activity. Furthermore, Pal also alleviated HUA-induced kidney injury, which was at least partially related to restoring Keap1-Nrf2 pathway and inhibiting TXNIP/NLRP3 inflammasome. Our investigation was envisaged to provide experimental support for the traditional application of CPA and CPA-containing classical herbal formulas in the management of HUA-related diseases and might provide novel dimension to the clinical application of Pal.

Correlation of uric acid with body mass index based on NHANES 2013-2018 data: A cross-sectional study

Clinical investigation of obesity-related risk factors aids in the early detection, prevention, and management of obesity. We aimed to examine the association between obesity and serum uric acid (sUA). A cross-sectional study was conducted including 18473 subjects from the National Health and Nutrition Examination Survey (NHANES). The exposure and outcome variables were sUA and body mass index (BMI), respectively. The weighted multivariate linear regression models and smooth curve fittings were conducted to assess the association between sUA and BMI. There were significantly positive correlations between sUA and BMI in both males and females (β = 1.414, 95% CI: 1.323-1.505, P < .0001, β = 1.853, 95% CI: 1.740-1.966, P < .0001, respectively). Furthermore, individuals in the higher sUA quartiles had higher BMI than those in the lowest quartile in both males and females. Subgroup analyses were stratified by race/ethnicity, results indicated the positive association of sUA with BMI in males remained in all races including Mexican American (β = 1.203, 95% CI: 0.965-1.442, P < .0001), other Hispanic (β = 1.126, 95% CI: 0.858-1.395, P < .0001), non-Hispanic White (β = 1.493, 95% CI: 1.343-1.642, P < .0001), non-Hispanic Black (β = 1.331, 95% CI: 1.122-1.540, P < .0001), and other races (β = 1.329, 95% CI: 1.115-1.544, P < .0001). And the positive association of sUA with BMI in females also remained in all races including Mexican American (β = 1.806, 95% CI: 1.520-2.092, P < .0001), other Hispanic (β = 2.033, 95% CI: 1.687-2.379, P < .0001), non-Hispanic White (β = 1.847, 95% CI: 1.657-2.037, P < .0001), non-Hispanic Black (β = 2.141, 95% CI: 1.874-2.408, P < .0001), and other races (β = 1.348, 95% CI: 1.081-1.615, P < .0001). The current cross-sectional study with 18473 US participants found that an elevated sUA was positively correlated with a higher BMI in males, females, and all kinds of races.

Sacha Inchi Oil Press-Cake Protein Hydrolysates Exhibit Anti-Hyperuricemic Activity via Attenuating Renal Damage and Regulating Gut Microbiota

The incidence of hyperuricemia has increased globally due to changes in dietary habits. The sacha inchi oil press-cake is generally discarded, resulting in the waste of resources and adverse environmental impact. For the purpose of developing sacha inchi oil press-cake and identifying natural components with anti-hyperuricemic activities, we systemically investigated the underlying mechanisms of sacha inchi oil press-cake protein hydrolysates (SISH) in the hyperuricemic rat model. SISH was obtained from sacha inchi oil press-cake proteins after trypsin treatment, and 24 peptides with small molecular weight (<1000 Da) were identified. The results of animal experiments showed that SISH significantly decreased the serum uric acid (UA) level by inhibiting the xanthine oxidase (XOD) activity and regulating the gene expression related to UA production and catabolism in hyperuricemia rats, such as Xdh and Hsh. In addition, SISH attenuated the renal damage and reduced the gene expression related to inflammation (Tlr4, Map3k8, Pik3cg, Pik3ap1, Ikbke, and Nlrp3), especially Tlr4, which has been considered a receptor of UA. Notably, SISH reversed high purine-induced gut microbiota dysbiosis, particularly by enhancing the relative abundance of butyric acid-producing bacteria (unidentified_Ruminococcaceae, Oscillibacter, Ruminiclostridium, Intestinimonas). This research provided new insights into the treatment of hyperuricemia.

Hyperuricemia, a Non-Independent Component of Metabolic Syndrome, Only Predicts Renal Outcome in Chronic Kidney Disease Patients without Metabolic Syndrome or Diabetes

Uric acid (UA) is elevated in metabolic syndrome (MS) and diabetes (DM). UA is associated with central obesity and blood glucose and is proposed as a criterion of MS. Previous reports showed that UA could predict renal outcome in CKD. However, recent clinical trials did not demonstrate the benefits of urate-lowering agents (ULA) for renal outcome. Whether the prognostic value of UA for renal outcome is independent of MS or secondary to MS in CKD patients is unknown. Our study included 2500 CKD stage 1−4 Asian patients divided by UA tertiles and MS/DM. In linear regression, UA was associated with obesity, C-reactive protein, and renal function. In Cox regression, high UA was associated with worse renal outcome in non-MS/DM, but not in MS/DM: hazard ratio (95% confidence interval) of UA tertile 3 was 3.86 (1.87−7.97) in non-MS/DM and 1.00 (0.77−1.30) in MS/DM (p for interaction < 0.05). MS was associated with worse renal outcome, but redefined MS (including hyperuricemia as the 6th criteria) was not. In conclusion, hyperuricemia is associated with worse renal outcome in non-MS/DM and is not an independent component of MS in CKD stage 1−4 patients. Hyperuricemia secondary to MS could not predict renal outcome.

Highly sensitive determination of paracetamol, uric acid, dopamine, and catechol based on flexible plastic electrochemical sensors

Flexible sensing is an alternative to traditional sensing and possesses good flexibility and wearability. Intrinsically conductive polymers, particularly poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS), have received significant attention due to their high mechanical flexibility and good biocompatibility. Here, we report the design of highly conductive and electrochemically active PEDOT:PSS-coated plastic substrate electrodes by combining N-doped graphene (NG) or S-doped graphene (SG) with methanesulfonic acid-treated PEDOT:PSS (denoted as NG-f-MSA-PEDOT:PSS/PET and SG-f-MSA-PEDOT:PSS/PET) by a simple drop-coating method. At room temperature, the NG-f-MSA-PEDOT:PSS/PET electrode demonstrated the lowest detection limits of 17.09, 33.84, 28.30, and 44.96 nM for paracetamol, uric acid, dopamine, and catechol (S/N = 3), respectively. The NG-f-MSA-PEDOT:PSS/PET electrode had good anti-interference ability and reproducibility without employing expensive noble metals and requiring much effort to polish the surface of traditional glass carbon electrodes. Most importantly, this film electrode could maintain a stable electrochemical response under different bending and crease states and had excellent mechanical stability and flexibility.

Anti-inflammatory and immunomodulatory activity of Mangifera indica L. reveals the modulation of COX-2/mPGES-1 axis and Th17/Treg ratio

In the context of inflammation and immunity, there are fragmented and observational studies relating to the pharmacological activity of Mangifera indica L. and its main active component, mangiferin. Therefore, we aimed to analyze the potential beneficial effects of this plant extract (MIE, 90% in mangiferin) in a mouse model of gouty arthritis, to allow the evaluation of cellular immune phenotypes and the biochemical mechanism/s beyond MIE activity. Gouty arthritis was induced by the intra-articular administration of MSU crystals (200μg 20μl^-1), whereas MIE (0.1-10mgkg^-1) or corresponding vehicle (DMSO/saline 1:3) were orally administrated concomitantly with MSU (time 0), 6 and 12h after the stimulus. Thereafter, knee joint score and oedema were evaluated in addition to western blot analysis for COX-2/mPGES-1 axis. Moreover, the analysis of pro/anti-inflammatory cyto-chemokines coupled with the phenotyping of the cellular infiltrate was performed. Treatment with MIE revealed a dose-dependent reduction in joint inflammatory scores with maximal inhibition observed at 10mgkg^-1. MIE significantly reduced leukocyte infiltration and activation and the expression of different pro-inflammatory cyto-chemokines in inflamed tissues. Furthermore, biochemical analysis revealed that MIE modulated COX-2/mPGES-1 and mPGDS-1/PPARγ pathways. Flow cytometry analysis also highlighted a prominent modulation of inflammatory monocytes (CD11b⁺/CD115⁺/LY6C^hi), and Treg cells (CD4⁺/CD25⁺/FOXP3⁺) after MIE treatment. Collectively, the results of this study demonstrate a novel function of MIE to positively affect the local and systemic inflammatory/immunological perturbance in the onset and progression of gouty arthritis.

Effects of uric acid-lowering therapy in patients with essential arterial hypertension

OBJECTIVES

Asymptomatic hyperuricemia (AHU) is elevated serum uric acid (UA) without symptoms. This study aimed to determine the effects of AHU treatment with allopurinol on selected hypertension-mediated organ damage (HMOD) indices in patients with uncomplicated essential arterial hypertension (AH).

METHODS

Patients aged 30-70 years with AHU and AH grade 1-2 with adequate blood pressure (BP) control, without previous urate-lowering therapy (ULT), were divided into two groups: (a) ULT (receiving allopurinol) and (b) control (age- and sex-matched patients without ULT). Both received a UA-lowering diet. BP (office, 24 h and central), echocardiographic parameters, carotid intima-media thickness (IMT) and lab tests [high-sensitivity C-reactive protein (hs-CRP)] were measured at baseline and at 6 months follow-up.

RESULTS

Of 100 participants, 87 (44 ULT, 43 controls) completed the study. At 6 months follow-up, there was a greater reduction in serum UA concentration in the ULT group than in the control group. Patients receiving allopurinol had significant reductions in office systolic and diastolic BP, central systolic BP, pulse pressure, IMT (0.773 ± 0.121 vs. 0.752 ± 0.13 mm, P = 0.044) and hs-CRP (3.36 ± 2.73 vs. 2.74 ± 1.91 mg/L, P = 0.028) compared to controls. Multivariate regression analysis revealed the independent relationship between reduction in IMT and UA lowering (P < 0.026).

CONCLUSION

In patients with AH and AHU, treatment with allopurinol leads to improvement in BP control and reduction in HMOD intensity, in particular IMT. The decrease in hs-CRP concentration associated with ULT may have a beneficial effect on a patient's long-term prognosis.

Clinicopathological Patterns and Outcomes in Patients with Lupus Nephritis and Hyperuricemia

A limited number of large cohort studies have reported the clinicopathological characteristics and prognosis of patients with lupus nephritis (LN) and hyperuricemia (HUA). In this retrospective cohort study, 1297 LN patients were enrolled from January 1996 to December 2011 in the First Affiliated Hospital of Sun Yat-Sen University, and HUA occurred in 649 (50.04%) of these 1297 LN patients. Compared to patients without HUA, those with HUA presented with higher blood pressure and triglyceride levels, lower hemoglobin and serum albumin levels, worse renal function, more severe hematuria and proteinuria, higher lupus activity, and more positive antiphospholipid antibody. Pathologically, HUA cases presented more crescents, a higher degree of mesangial matrix, endothelial cell proliferation, and inflammatory cell infiltration. During the 52-month follow-up, the 5-year and 10-year incidence rates of renal endpoint events were 11.1% and 19.5% in the HUA group, and 8.3% and 13.8% in the non-HUA group, respectively (p = 0.073). In addition, the 5-year and 10-year mortality rates did not differ significantly between the HUA (12.0% and 18.2%) and non-HUA (12.2% and 17.5%) groups, respectively. This study verified that HUA was not an independent risk for poor clinical outcomes, and steroids that delay the deterioration of renal function did not affect the survival of these patients.

Cardiovascular Risks in Korean Patients with Gout: Analysis Using a National Health Insurance Service Database

Although several epidemiologic studies have shown the association between gout and cardiovascular outcomes, specific risk factors for developing cardiovascular diseases in Asian patients with gout are undisclosed. Thus, the purpose of this study was to investigate risks of cardiovascular outcomes and its related factors in Korean patients with gout. This retrospective clinical study used sampled cohort data from the National Health Insurance Service in Korea. Patients with gout were defined as subjects enlisted with an ICD-10 code (M10). Control patients were selected by frequency matching for age, sex, and index year. Primary outcomes included ischemic heart disease (IHD), congestive heart failure, cerebrovascular disease (CVD), or transient ischemic attack. We calculated the hazard ratio (HR) using Cox regression, adjusting potential confounders including age, sex, lifestyle habits, laboratory results, and medication. We identified 3306 patients with gout and an equal number of matched controls. Multivariate Cox regression analysis showed that gout patients had increased risks of IHD (HR: 1.860, 95% CI: 1.446–2.392), acute myocardial infarction (HR: 3.246, 95% CI: 1.460–7.217), and CVD (HR: 1.552, 95% CI: 1.177–2.036). Old age, current smoking, frequent alcohol intake, high low-density lipoprotein, and diabetes mellitus increased the risk of cardiovascular outcomes, yet hypouricemic agents decreased the risk of cerebrovascular diseases. Our data corroborate that it is crucial to identify and manage traditional cardiovascular risk factors alongside lowering urate levels in patients with gout.

Traditional Chinese Herbal Medicine Plays a Role in the Liver, Kidney, and Intestine to Ameliorate Hyperuricemia according to Experimental Studies

In the last few decades, hyperuricemia has drawn increasing attention owing to its global prevalence. Observational surveys have manifested that there is a relation between hyperuricemia and increased risks of hypertension, chronic kidney disease, cardiovascular events, metabolic disorders, end stage renal disease, and mortality. As alternatives, Traditional Chinese medicinal herbs have demonstrated concrete effects in mitigating hyperuricemia in different experiments. Researchers have made efforts to investigate the role of herbal medicine in attenuating hyperuricemia. This review focuses on traditional Chinese herbal medicines that have been reported to ameliorate hyperuricemia in experimental studies.

Inosine induces acute hyperuricaemia in rhesus monkey (Macaca mulatta) as a potential disease animal model

CONTEXT

The uric acid metabolism pathway is more similar in primates and humans than in rodents. However, there are no reports of using primates to establish animal models of hyperuricaemia (HUA).

OBJECTIVES

To establish an animal model highly related to HUA in humans.

MATERIALS AND METHODS

Inosine (75, 100 and 200 mg/kg) was intraperitoneally administered to adult male rhesus monkeys (n = 5/group). Blood samples were collected over 8 h, and serum uric acid (SUA) level was determined using commercial assay kits. XO and PNP expression in the liver and URAT1, OAT4 and ABCG2 expression in the kidneys were examined by qPCR and Western blotting to assess the effects of inosine on purine and uric acid metabolism. The validity of the acute HUA model was assessed using ulodesine, allopurinol and febuxostat.

RESULTS

Inosine (200 mg/kg) effectively increased the SUA level in rhesus monkeys from 51.77 ± 14.48 at 0 h to 178.32 ± 14.47 μmol/L within 30 min and to peak levels (201.41 ± 42.73 μmol/L) at 1 h. PNP mRNA level was increased, whereas XO mRNA and protein levels in the liver were decreased by the inosine group compared with those in the control group. No changes in mRNA and protein levels of the renal uric acid transporter were observed. Ulodesine, allopurinol and febuxostat eliminated the inosine-induced elevation in SUA in tested monkeys.

CONCLUSIONS

An acute HUA animal model with high reproducibility was induced; it can be applied to evaluate new anti-HUA drugs in vivo and explore the disease pathogenesis.

Structural and biochemical insights into a hyperthermostable urate oxidase from Thermobispora bispora for hyperuricemia and gout therapy

Microbial urate oxidase has emerged as a potential source of therapeutic properties for hyperuricemia in arthritic gout and renal disease. The thermostability and long-term thermal tolerance of the enzyme need to be established to prolong its therapeutic effects. Here, we present the biochemical and structural aspects of a hyperthermostable urate oxidase (TbUox) from the thermophilic microorganism Thermobispora bispora. Enzymatic characterization of TbUox revealed that it was active over a wide range of temperatures, from 30 to 70 °C, with optimal activity at 65 °C and pH 8.0, which suggests its applicability under physiological conditions. Moreover, TbUox exhibits high thermostability from 10 to 65 °C, with Tm of 70.3 °C and near-neutral pH stability from pH 7.0 to 8.0 and high thermal tolerance. The crystal structures of TbUox revealed a distinct feature of the C-terminal loop extensions that may help with protein stability via inter-subunit interactions. In addition, the high thermal tolerance of TbUox may be contributed by the extensive inter-subunit contacts via salt bridges, hydrogen bonds, and hydrophobic interactions. The findings in this study provide a molecular basis for the thermophilic TbUox urate oxidase for application in hyperuricemia and gout therapy.

Antihyperuricemic Effect of Green Alga Ulva lactuca Ulvan through Regulating Urate Transporters

A novel polysaccharide from Ulva lactuca (ULP) was purified using a Sepharose CL-4B column. Fourier transform infrared spectroscopy, high-performance liquid chromatography, and nuclear magnetic resonance spectroscopy were employed to analyze the structure of ULP. It consisted of rhamnose (Rha), glucuronic acid (GluA), galactose (Gal), and xylose (Xyl) at a molar ratio of 32.75:22.83:1.07:6.46 with the molecular weight of 2.24 × 10⁵ Da. The four major glycosidic residues found in ULP were →2,3)-α-l-Rhap-(1→, →4)-β-d-GlcpA-(1→, →2,6)-β-d-Galp-(1→, and →4)-β-d-Xylp-(1→. The antihyperuricemic activity of ULP was exhibited by detecting related biochemical indexes, urate transporter gene expressions, renal histopathology, and intestinal microbiota shifts. ULP obviously decreased the levels of serum uric acid (UA), blood urea nitrogen, and creatinine, while inhibited serum and hepatic xanthine oxidase activities as well as improved renal injury in hyperuricemic mice. Furthermore, the upregulation of UA excretion genes ABCG2/OAT1 and downregulation of UA resorption genes URAT1 and GLUT9 were detected. In addition, ULP exerted its antihyperuricemic effect through regulating the intestinal microbiome, characterized by elevating the helpful microbial abundance, meanwhile declining the harmful bacterial abundance and restoring the gut microbiome homeostasis. This study demonstrates the antihyperuricemic activity of ULP and its potential effect for the treatment of hyperuricemia-related diseases.

Anti-hyperuricemic and nephroprotective effects of whey protein hydrolysate in potassium oxonate induced hyperuricemic rats

BACKGROUND

Hyperuricemia (HUA) is a serious public health concern globally that needs to be solved. It is closely related to gout and other metabolic diseases. To develop a safe and effective dietary supplementation for alleviating HUA, we investigated the effects of whey protein hydrolysate (WPH) on HUA and associated renal dysfunction and explored their underlying mechanism.

RESULTS

Potassium oxonate was used to induce HUA in model rats, who were then administered WPH for 21 days. The results showed that WPH significantly inhibited xanthine oxidase and adenosine deaminase activity in serum and liver, decreased uric acid (UA), creatinine, and blood urea nitrogen levels in serum, and increased the UA excretion in urine. In addition, WPH downregulated the expression of urate transporter 1 and upregulated the expression of organic anion transporter 1, adenosine triphosphate binding cassette subfamily G member 2, organic cation/carnitine transporters 1 and 2, and organic cation transporter 1 in kidneys.

CONCLUSION

These findings demonstrated for the first time that WPH could alleviate HUA by inhibiting UA production and promoting UA excretion, and improve the renal dysfunction caused by HUA. Thus, WPH may be a potential functional ingredient for the prevention and treatment of HUA and associated renal dysfunction. © 2021 Society of Chemical Industry.

Hyperuricemia, the heart, and the kidneys - to treat or not to treat?

Background

Hyperuricemia is a state in which the serum levels of uric acid are elevated. As such it has a pronounced effect on vascular and renal function with their consequences, while also showing some antioxidant effects that show to be beneficial.

Summary

Hyperuricemia has shown to have a J-shaped relationship with mortality, is frequently associated with development and progression of heart and kidney disease, and is correlated with malnutrition-inflammation-atherosclerosis syndrome, although several Mendelian studies have failed to show an association with morbidity and mortality. Hyperuricemia is usually associated with gout flares and tophi development but can also present as asymptomatic hyperuricemia. It is still uncertain whether asymptomatic hyperuricemia is an independent risk factor for cardiovascular or renal disease and as such its treatment is questionable.

Key messages

Some possible tools for future decision making are the use of noninvasive techniques such as pulse wave analysis, urinary sediment analysis, and joint ultrasound, which could help identify individuals with asymptomatic hyperuricemia that could benefit from urate lowering therapy most.

Molecular Elucidation of a Urate Oxidase from Deinococcus radiodurans for Hyperuricemia and Gout Therapy

Urate oxidase initiates the uric acid degradation pathways and is extensively used for protein drug development for gout therapy and serum uric acid diagnosis. We first present the biochemical and structural elucidation of a urate oxidase from the extremophile microorganism Deinococcus radiodurans (DrUox). From enzyme characterization, DrUox showed optimal catalytic ability at 30 °C and pH 9.0 with high stability under physiological conditions. Only the Mg²⁺ ion moderately elevated its activity, which indicates the characteristic of the cofactor-free urate oxidase family. Of note, DrUox is thermostable in mesophilic conditions. It retains almost 100% activity when incubated at 25 °C and 37 °C for 24 h. In this study, we characterized a thermostable urate oxidase, DrUox with high catalytic efficiency and thermal stability, which strengthens its potential for medical applications.

Asymptomatic hyperuricaemia and coronary artery disease

BACKGROUND

Uric acid has been related to a tendency to precipitate to form crystals, presenting asymptomatically, until the formation of arthritis, tophi or renal lithiasis. Previously, the presence of asymptomatic hyperuricaemia has been associated with the presence of cardiovascular disease.

OBJECTIVES

To determine the association of complex coronary artery disease in patients with asymptomatic hyperuricaemia.

MATERIAL AND METHODS

An observational retrospective, transversal, unicentric study was conducted in a tertiary hospital in Mexico, in the period from June 2017 to March 2019. All patients admitted for coronary angiography were included; patients with gout, use of diuretics and chronic kidney disease were excluded.

RESULTS

During the study period, a total of 300 patients were collected, of which 40% presented hyperuricaemia. The patients with hyperuricaemia were older (59 vs. 63, P = .002). The group of patients with asymptomatic hyperuricaemia had a higher proportion of complex coronary lesions (64 vs. 35%, P ≤ .0001) as well as a higher SYNTAX I score (27 vs. 17, P ≤ .001). There was a higher probability of presenting complex coronary lesions in this group of patients (OR 3.4, P ≤ .0001). In addition, in the group division of uric acid levels, it was related to the presence of complex coronary lesions (Q1 = .5, P = .06), (Q2 = 2, P = .01) and (Q3 = 3, P ≤ .0001).

CONCLUSION

Asymptomatic hyperuricaemia has a higher prevalence and association of presenting complex coronary lesions.

Comparative effects of quercetin, luteolin, apigenin and their related polyphenols on uric acid production in cultured hepatocytes and suppression of purine bodies-induced hyperuricemia by rutin in mice

Hyperuricemia, the high uric acid (UA) state in blood, has been accepted as an important risk factor for gout. The liver is a main factory of UA production. In the present study, we have examined the effects of three kinds of flavonol and flavones as typical aglycons, i.e., quercetin, luteolin, apigenin, their glycosides and related compounds, on UA productivity in cultured hepatocytes, adopting allopurinol as the positive control drug. Quercetin, luteolin, diosmetin (4'-O-methylluteolin) and apigenin at 10, 30 and 100 μM as well as allopurinol at 0.1, 0.3 and 1 μM dose-dependently and significantly decreased UA production in the hepatocytes, when compared with 0 μM (control). Both rutin (quercetin-3-O-rutinoside) and quercitrin (quercetin-3-O-ramnoside) significantly reduced UA production in the hepatocytes at 100 μM. Luteolin glycosides such as orientin (luteolin-8-C-glucoside) and isoorientin (luteolin-6-C-glucoside) exerted no influences on it even at 100 μM. Likewise, apigenin glycosides such as vitexin (apigenin-8-C-glucoside) and isovitexin (apigenin-6-C-glucoside) showed no inhibitory effect on it, while apigetrin (apigenin-7-O-glucoside) significantly reduced it at 100 μM. In model mice with purine bodies-induced hyperuricemia, allopurinol completely suppressed the hyperuricemia at a dose of 10 mg/kg body weight. Rutin suppressed significantly the hyperuricemia at a dose of 300 mg/kg body weight, while vitexin showed no significant effect up to 300 mg/kg body weight. Thus, rutin (O-glycoside) is demonstrated to be hypouricemic in both cultured hepatocytes and model mice with recently contrived purine bodies-induced hyperuricemia.

Cardiovascular events in hyperuricemia population and a cardiovascular benefit-risk assessment of urate-lowering therapies: a systematic review and meta-analysis

BACKGROUND

Hyperuricemia and gout have become public health concerns; many important guidelines have recommended xanthine oxidase inhibitors (XOIs) as the first-line urate-lowering therapies (ULTs) to treat chronic gout with hyperuricemia. However, whether treating hyperuricemia and gout with ULTs modifies cardiovascular risks remains controversial. The aim of this study was to assess the incident risk of cardiovascular (CV) events (CVE) in hyperuricemia population, assess the cardiovascular benefit-risk of ULTs in hyperuricemia patients with or without gout in diverse cardiovascular risk sub-groups, and specify the safety of different ULTs.

METHODS

We searched PubMed, Embase, the Cochrane Library, Wanfang, Chongqing VIP (CQVIP, en.cqvip.com), and China National Knowledge Infrastructure Database for prospective cohort studies and randomized controlled trials (RCTs) in English and Chinese. Potential medications included XOIs, and uricosurics. RCTs were divided into sub-groups analysis based on blinding status and patients' history of CV diseases. Risk ratios (RRs) were calculated and were reported with corresponding 95% confidence intervals (CIs) by fixed-effects or random-effects model.

RESULTS

Seven prospective cohort studies and 17 RCT studies were included. The risks of both major adverse cardiovascular events (MACE) (RR = 1.72, 95% CI 1.28-2.33) and CVE (RR = 1.35, 95% CI 1.12-1.62) were higher in the hyperuricemia population than non-hyperuricemia one. In seven RCT studies where XOIs were compared with no-treatment or placebo, the results of five low CV risk studies showed that XOIs lowered the risks of both MACE (RR = 0.35, 95% CI 0.20-0.62) and CVE (RR = 0.61, 95% CI 0.44-0.85); whereas two high CV risk studies showed that XOIs lowered the risk of CVE (RR = 0.69, 95% CI 0.54-0.88) rather than MACE (RR = 0.62, 95% CI 0.29-1.35). In nine RCT studies where the cardiovascular safety between febuxostat and allopurinol were compared, no statistical difference was found in the risk of MACE or CVE.

CONCLUSIONS

The hyperuricemia population does have a higher incidence of CVE, and the results suggested that XOIs might reduce the incidence of MACE and total CVE. In addition, from the perspective of cardiovascular safety, febuxostat equaled allopurinol in our meta-analysis.

Association of Hyperuricemia With Immune Disorders and Intestinal Barrier Dysfunction

Background

More than 30–40% of uric acid is excreted via the intestine, and the dysfunction of intestinal epithelium disrupts uric acid excretion. The involvement of gut microbiota in hyperuricemia has been reported in previous studies, but the changes and mechanisms of intestinal immunity in hyperuricemia are still unknown.

Methods

This study developed a urate oxidase (Uox)-knockout (Uox–/–) mouse model for hyperuricemia using CRISPR/Cas9 technology. The lipometabolism was assessed by measuring changes in biochemical indicators. Furthermore, 4-kDa fluorescein isothiocyanate–labeled dextran was used to assess gut barrier function. Also, 16S rRNA sequencing was performed to examine the changes in gut microbiota in mouse feces. RNA sequencing, Western blot, Q-PCR, ELISA, and immunohistochemical analysis were used for measuring gene transcription, the number of immune cells, and the levels of cytokines in intestinal tissues, serum, kidney, liver, pancreas, and vascellum.

Results

This study showed that the abundance of inflammation-related microbiota increased in hyperuricemic mice. The microbial pattern recognition–associated Toll-like receptor pathway and inflammation-associated TNF and NF-kappa B signaling pathways were significantly enriched. The increased abundance of inflammation-related microbiota resulted in immune disorders and intestinal barrier dysfunction by upregulating TLR2/4/5 and promoting the release of IL-1β and TNF-α. The levels of epithelial tight junction proteins occludin and claudin-1 decreased. The expression of the pro-apoptotic gene Bax increased. The levels of LPS and TNF-α in systemic circulation increased in hyperuricemic mice. A positive correlation was observed between the increase in intestinal permeability and serum levels of uric acid.

Conclusion

Hyperuricemia was characterized by dysregulated intestinal immunity, compromised intestinal barrier, and systemic inflammation. These findings might serve as a basis for future novel therapeutic interventions for hyperuricemia.

Lycium barbarum polysaccharides protect mice from hyperuricaemia through promoting kidney excretion of uric acid and inhibiting liver xanthine oxidase

CONTEXT

Lycium barbarum L. (Solanaceae) polysaccharides (LBPs) are important active constituents that have demonstrated kidney protection.

OBJECTIVE

This study investigated the effect of LBPs on hyperuricaemia and explored the underlying mechanism in mice.

MATERIALS AND METHODS

Thirty-six C57BL/6 mice were randomly divided into the control group, hyperuricaemia group, allopurinol group (5 mg/kg) and three LBP groups (n = 6). The LBP groups were treated orally with LBPs at 50, 100 and 200 mg/kg body weight for 7 days. We examined the levels of serum uric acid (S_UA) and urinary uric acid (U_UA), as well as xanthine oxidase (XOD) activities. mRNA and protein were quantified by quantitative real-time PCR and Western blotting, respectively.

RESULTS

LBPs treatment (100 and 200 mg/kg) significantly reduced the S_UA levels to 4.83 and 4.48 mg/dL, and markedly elevated the U_UA levels to 4.68 and 5.18 mg/dL (p < 0.05), respectively, while significantly increased the mRNA and protein expression levels of renal organic anti-transporter 1 (OAT1) and organic anti-transporter 3 (OAT3), and markedly decreased the levels of glucose transporter 9 (GLUT9) (p < 0.05). Additionally, the serum XOD activities were reduced to 31.5 and 31.1 mU/mL, and the liver XOD activities were reduced to 80.6 and 75.6 mU/mL after treatment with 100 and 200 mg/kg LBPs (p < 0.01), respectively.

DISCUSSION AND CONCLUSIONS

This study demonstrated the potential role of LBPs in reducing the uric acid level in hyperuricemic mice. A border study population should be evaluated. These results are valuable for the development of new anti-hyperuricaemia agents from LBPs.

Depressive Symptoms and the Effectiveness of a Urate‐Lowering Therapy in a Clinical Trial

Objective

Methods

Results

Conclusion

Combined effects of MSU crystals injection and high fat-diet feeding on the establishment of a gout model in C57BL/6 mice

OBJECTIVE

Gout is characterized by inflammatory arthritis with hyperuricaemia and deposition of monosodium urate (MSU) crystals in the joints. Several animal models have been proposed based on MSU crystals injection or high-fat diet feeding; however, neither hyperuricaemia model nor acute gout model can effectively reflect clinical features of gout. This study aimed to assess the effectiveness of a compound gout model induced by the combination of MSU crystals injection and high-fat diet feeding.

METHODS

The compound gout model was induced by high-fat diet feeding per day and the intraplantar injection of MSU crystals (1 mg) into the footpad of each mouse every 10 days. Serum uric acid, foot swelling and pain analyses were performed at days 22, 32 and 42. Gout inflammation, serum proinflammatory cytokines and gut microbiota analyses were performed only at day 42.

RESULTS

Compared to hyperuricaemia model or acute gout model, the compound gout model showed little advantages of elevating serum uric acid, causing foot swelling and gout inflammation, while it caused more severe serum inflammation and gut microbiota dysbiosis. Severe serum inflammation in the compound gout model could be reflected by the increased levels of IL-1α, IL-4, IL-6, IL-10, IL-12p40, IL-12p70, IFN-γ, KC, MCP-1 and MIP-1β. In addition, the compound gout model induced more alterations in the gut microbiota, including increasing levels of Desulfovibrio and Parasutterella.

CONCLUSION

The injection of MSU and feed of high-fat diet have a combined effect on elevating serum inflammation and causing gut microbiota disorders in the process of establishing a gout model.

Pilot study: asymptomatic hyperuricemia patients with obesity and nonalcoholic fatty liver disease have increased risk of double contour sign

BACKGROUND/AIMS

Double contour sign (DCS) is a representative ultrasonographic finding in gout. DCS is evidence of monosodium urate deposit in gouty arthritis and has been identified in some patients with asymptomatic hyperuricemia. However, the specific characteristics of asymptomatic hyperuricemia in patients with DCS have not yet been revealed.

METHODS

We enrolled patients with incidentally found hyperuricemia. Baseline characteristics were compared between asymptomatic hyperuricemia patients with and without DCS. Logistic regression analysis was performed to determine associated factors for DCS in patients with asymptomatic hyperuricemia.

RESULTS

A total of 62 patients with asymptomatic hyperuricemia were enrolled, and 22 of the patients showed DCS. The metatarsophalangeal were the most commonly affected joints, and differences between asymptomatic hyperuricemia patients with and without DCS were seen in aspects of class II obesity and nonalcoholic fatty liver disease (NAFLD). Multivariate logistic regression analysis demonstrated that class II obesity and NAFLD significantly increased the risk of DCS in asymptomatic hyperuricemia patients (odds ratio [OR], 6.58, p = 0.022; OR, 5.21, p = 0.020, respectively).

CONCLUSION

Asymptomatic hyperuricemia patients with class II obesity and NAFLD had increased risk of DCS. Determining the presence of crystal deposition, such as DCS, among patients with asymptomatic hyperuricemia might help determine whether early pharmacologic intervention is needed, especially with severe obesity or NAFLD.

Risk of Parkinson's disease following gout: a population-based retrospective cohort study in Taiwan

Background

The progressive neurodegenerative disorder Parkinson disease (PD) is well-established as the second most common neurodegenerative disease. Associations between the sequential risk of PD and gout have been addressed in other studies, but findings have been inconclusive. Accordingly, we executed the present study with the purpose of assessing PD risk in patients with gout.

Methods

From Taiwan’s National Health Insurance Research Database, we identified the data of patients newly diagnosed as having gout between January 1, 2000 and December 1, 2000. A cohort of patients without gout, matched for sex and age, was constructed for comparison. Hazard ratios (HRs) and the incidence rate of subsequent PD were calculated for both cohorts and separately for male and female groups. The gout and comparison cohorts consisted of 7900 patients each.

Results

The HR for PD was not significantly higher in the gout cohort compared with the control cohort (HR 1.01, 95% confidence interval [CI], 0.93–1.31, P = .268), even after adjustment for age, urbanization, monthly income, sex, and comorbidities. We did not observe gender differences in the gout–PD association (male: HR 1.01, 95% CI, 0.88–1.36, P = .400; female: HR 1.11, 95% CI, 0.84–1.46, P = .466).

Conclusions

Our study identified that there was no protective effect of gout for the risk of PD in the Taiwanese population.

Quantification of uric acid in vasculature of patients with gout using dual-energy computed tomography

BACKGROUND

Gout, caused by hyperuricemia and subsequent deposition of aggregated monosodium urate crystals (MSU) in the joints or extra-articular regions, is the most common inflammatory arthritis. There is increasing evidence that gout is an independent risk factor for hypertension, cardiovascular disease progression and mortality.

AIM

To evaluate if dual energy computed tomography (DECT) could identify MSU within vessel walls of gout patients, and if MSU deposits within the vasculature differed between patients with gout and controls. This study may help elucidate why individuals with gout have increased risk for cardiovascular disease.

METHODS

31 gout patients and 18 controls underwent DECT scans of the chest and abdomen. A material decomposition algorithm was used to distinguish regions of MSU (coded green), and calcifications (coded purple) from soft tissue (uncoded). Volume of green regions was calculated using a semi-automated volume assessment program. Between-group differences were analyzed using Mann-Whitney U exact test and nonparametric rank regression.

RESULTS

Gout patients had significantly higher volume of MSU within the aorta compared to controls [Median (Min-Max) of 43.9 (0-1113.5) vs 2.9 (0-219.4), P = 0.01]. Number of deposits was higher in gout patients compared to controls [Median (Min-Max) of 20 (0-739) vs 1.5 (0-104), P = 0.008]. However, the difference was insignificant after adjustment for age, gender, history of cardiovascular disease and diabetes. Increased age was positively associated with total urate volume (r_s = 0.64; 95% confidence interval: 0.43-0.78).

CONCLUSION

This pilot study showed that DECT can quantify vascular urate deposits with variation across groups, with gout patients possibly having higher deposition. This relationship disappeared when adjusted for age, and there was a positive relationship between age and MSU deposition. While this study does not prove that green coded regions are truly MSU deposition, it corroborates recent studies that show the presence of vascular deposition.

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.

Efficacy and safety of urate-lowering treatments in patients with hyperuricemia: A comprehensive network meta-analysis of randomized controlled trials

WHAT IS KNOWN AND OBJECTIVE

Hyperuricemia (HUA) and gout are considerable public health problems because of their increasing incidence and interactions with other diseases. We aimed to evaluate the efficacy and safety of urate-lowering therapies (ULTs) for patients.

METHODS

A systematic literature review was conducted, and a network meta-analysis was performed on the included studies using the Markov Chain Monte Carlo simulation method and a Bayesian statistical framework. We calculated surface under the cumulative ranking curve (SUCRA) values and performed clustered ranking to combine the efficacy and safety results.

RESULTS

Twenty-two randomized controlled studies were identified for the efficacy analysis, and 20 studies were identified for the safety analysis. Compared with the placebo, the ULTs were efficient and safe. Febuxostat 120 mg/d and allopurinol 200 mg/d had the highest SUCRA scores for efficacy and safety, respectively. Clustered ranking results showed that febuxostat 120 mg/d was the best in terms of efficacy and safety, topiroxostat 120/160 mg/d was similar to febuxostat 80 mg/d in terms of efficacy but safer, and allopurinol was not inferior to topiroxostat.

WHAT IS NEW AND CONCLUSION

Febuxostat had the best efficacy and safety results among the tested agents, and topiroxostat and allopurinol appeared to have fewer adverse events.

Serum homocysteine levels and their association with clinical characteristics of inflammatory arthritis

OBJECTIVE

The aim of our study was to explore the serum levels of homocysteine (Hcy) and its association with clinical characteristics in patients with different types of inflammatory arthritis.

METHODS

A total of 242 patients diagnosed with inflammatory arthritis (which included rheumatoid arthritis (RA), ankylosing spondylitis (AS), and gout), 49 with osteoarthritis (OA), and 36 with hyperuricaemia (HUA) and 81 healthy controls (HCs) were enrolled for comparisons.

RESULTS

The serum Hcy levels of patients with RA, AS, and OA were comparable with those of the HC group (P > 0.05). However, the serum level of Hcy was significantly higher in patients with gout than in HCs (18.75 ± 9.98 vs. 14.20 ± 6.22 μmol/L, P = 0.007). In addition, we found that the serum Hcy level was much higher in RA patients who received methotrexate (MTX) therapy without folic acid supplementation than in those who received MTX with folic acid supplementation (13.39 ± 4.80 vs. 9.41 ± 2.04 μmol/L, P = 0.001). Furthermore, there was a positive correlation between uric acid and Hcy in patients without uric acid-lowering treatment (r = 0.537, P = 0.002), but the correlation was eliminated after adjusting uric acid-lowering treatment (r = 0.139, P = 0.393). Finally, consistent with the above findings, hyperhomocysteinaemia (HHcy) was more common in gout patients (P < 0.05).

CONCLUSION

Screening for HHcy in patients with gout and RA, especially RA patients treated with MTX, might be necessary, and patients with HHcy might benefit from earlier supplementation with folic acid. Key Points • Serum homocysteine (Hcy) was elevated and the rate of hyperhomocysteinaemia (HHcy) was significantly higher in gout. • Rheumatoid arthritis (RA) patients who received methotrexate (MTX) treatment without folic acid supplementation showed higher serum Hcy than those who received MTX treatment with folic acid supplementation. • The serum Hcy level was positively correlated with age in only RA patients. • Serum Hcy was correlated with uric acid in gout patients, but the correlation was eliminated after adjusting uric acid-lowering treatment.

Repeated measurements of serum urate and mortality: a prospective cohort study of 152,358 individuals over 8 years of follow-up

BACKGROUND

Longitudinal evidence on change of serum urate level with mortality risk is limited as prior studies have a measurement of serum urate at a single time point. Further, the combined effect of serum urate and systemic inflammation on mortality is unknown.

METHODS

We conducted a prospective cohort study of 152,358 participants (122,045 men and 30,313 women) with repeated measurements of serum urate in 2006, 2008, 2010, and 2012 (107,751 participants had all four measurements of serum urate). We used the Cox proportional hazard model to examine the association between cumulative average and changes in serum urate with mortality. The combined effect of serum urate and systemic inflammation was determined by testing the interaction of serum urate and high-sensitive C-reactive protein (hs-CRP) in relation to mortality risk.

RESULTS

During a median follow-up of 8.7 (interquartile range 6.3-9.2) years, we identified 7564 all-cause deaths, 1763 CVD deaths, 1706 cancer deaths, and 1572 other deaths. We observed U-shaped relationships of cumulative average serum urate with all-cause mortality, cardiovascular mortality, and other mortalities. Compared with participants with stable serum urate, those with greater increases in serum urate had a 1.7-fold elevated mortality (hazard ratio (HR) = 1.66, 95% confidence interval (CI) = 1.49-1.84), and those with decreased serum urate had a 2-fold elevated mortality risk (HR = 2.14, 95% CI 1.93-2.37). Participants with both hyperuricemia and hs-CRP had 1.6 times higher mortality, compared with those with low serum urate and hs-CRP levels (HR = 1.56, 95% CI 1.37-1.76).

CONCLUSIONS

We observed a U-shaped relationship of long-term cumulative average serum urate with all-cause mortality, cardiovascular mortality, and other mortalities. Compared with participants with relatively stable serum urate levels, a greater increase or decrease in serum urate was associated with elevated mortality. Participants with both hyperuricemia and high systemic inflammation had the greatest mortality risk compared with those with low serum urate and low hs-CRP levels.

Fluoride-induced renal dysfunction via respiratory chain complex abnormal expression and fusion elevation in mice

A fluoride exposure mouse model is established to evaluate the relationship between mitochondrial respiratory chain complexes and renal dysfunction. Morphological changes in kidney tissues were observed. Renal function and cell proliferation in the kidneys were evaluated. The expression of mitochondrial fusion protein including mitofusin-1 (Mfn1) and optic atrophy 1 (OPA1), and mitochondrial respiratory chain complex subunits, including NDUFV2, SDHA, CYC1 and COX Ⅳ, were detected via real-time polymerase chain reaction, immunohistochemistry staining and Western blot, respectively. Results showed that the structures of renal tubule, renal glomerulus and renal papilla were seriously damaged. Renal function was impaired, and cell proliferation was remarkably inhibited by excessive fluoride in kidney. The mRNA and protein expression levels of Mfn1, OPA1, NDUFV2, CYC1 and COX Ⅳ were significantly increased after excessive fluoride exposure. However, the mRNA and protein expression of SDHA significantly decreased. Overall, our findings revealed that excessive fluoride can damage kidney structure, inhibit renal cell proliferation, interfere with the expression of mitochondrial respiratory chain complexes and elevate mitochondrial fusion. Consequently, renal function disorder occurred.

Severity of Hypertension Mediates the Association of Hyperuricemia With Stroke in the REGARDS Case Cohort Study

Previous studies do not widely support hyperuricemia as a risk factor for stroke and other cardiovascular diseases. We assessed the relationship between hyperuricemia and ischemic stroke (≈900 cases) using a large data set from the REGARDS study (Reasons for Geographic and Racial Differences in Stroke). We employed a case-cohort design (incident stroke cases and randomly selected cohort participants) and weighted Cox-proportional hazard models to estimate the association of serum urate level ≥6.8 mg/dL (ie, hyperuricemia) and 6.0 to <6.8 mg/dL versus <6.0 mg/dL (reference) with incident stroke. Analyses were stratified by race, gender, and age. Mediation of cardiovascular disease comorbidities on the serum urate-stroke association was tested. Hyperuricemia was associated with stroke (hazard ratio, 1.40 [95% CI, 1.10-1.78]) after adjustment for demographic variables and systolic and diastolic blood pressure. This association was substantially attenuated (hazard ratio, 1.17 [95% CI, 0.90-1.51]) by additional covariate adjustment. In particular, apparent treatment-resistant hypertension (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg on 3 antihypertensive medications or use of ≥4 antihypertensive medications) and the count of antihypertensive medication classes significantly reduced the effect of hyperuricemia on ischemic stroke. Specifically, apparent treatment-resistant hypertension and number of antihypertensive, respectively, mediate 45% and 43% of the association. There was no effect modification in the association between hyperuricemia and stroke by age, race, or gender. We conclude that hyperuricemia may be a risk factor for stroke. The substantial attenuation of this association by apparent treatment-resistant hypertension and number of antihypertensive suggests that severe hypertension may be a mediator.

Elevated Uric Acid Levels Promote Vascular Smooth Muscle Cells (VSMC) Proliferation via an Nod-Like Receptor Protein 3 (NLRP3)-Inflammasome-Dependent Mechanism

BACKGROUND Hyperuricemia has a pathogenic role in the development of hypertension and other cardiovascular diseases (CVD). Uric acid has been reported to activate Nod-like receptor protein 3 (NLRP3)-inflammasome and alter vascular smooth muscle cells (VSMC). However, the potential mechanisms underlying this association are still not understood. The aim of this study was to investigate the role and potential mechanisms of uric acid in proliferation of VSMC. MATERIAL AND METHODS Cell Counting Kit-8 (CCK-8) proliferation assay and colony formation assay were performed to determine the proliferative ability of VSMC under uric acid stimulation. Immunofluorescence microscopy was carried out to determine the expression of Alpha-smooth muscle actin (alpha-SMA). In addition, real-time PCR and Western blot were used to detect the expression of NLRP3-inflammasome, and ELISA was performed to measure the levels of IL-18 and IL-1ß. RESULTS The results showed that uric acid increases the proliferation of VSMC and induces alpha-SMA accumulation. We also found that uric acid increases the level of NLRP3 and induces NLRP3-inflammasome activation. The expressions of uric acid-induced inflammatory markers IL-1ß and IL-18 were decreased by the inhibitor MCC950. CONCLUSIONS Our findings revealed that uric acid induces inflammation through NLRP3-inflammasome-mediated VSMC proliferation. NLRP3 may be a new therapeutic target for hypertension.

The association of serum uric acid levels in psoriasis patients: A systematic review and network meta-analysis

BACKGROUND

Current research has proved that psoriasis is associated with serum uric acid (SUAC) levels. Our purpose is to clarify SUAC levels and the incidence of hyperuricemia in psoriasis patients, and to compare SUCA levels in different groups' psoriasis patients.

METHODS

We plan to search 7 electronic bibliographic databases (PubMed, Embase, Cochrane, and 4 Chinese databases) from inception to August 2019. Literatures selection and data collection will be performed independently by 2 authors. The Newcastle-Ottawa scale will be used to assess the methodologic quality and bias of included studies. Firstly, standard pairwise meta-analysis will be used to examine the considered data synthesis. Secondly, if the identified studies appear sufficiently similar within and across the different comparisons between different groups of psoriasis patients, we will estimate SUAC levels using network meta-analysis in different age and ethnicity psoriasis patients. Mean difference, risk ratio, and 95% confidence intervals will be used to assess the SUAC levels and the incidence of hyperuricemia in psoriasis patients. The software of Stata and WinBUGS will be used to calculations.

RESULTS

The results will be published in a peer-reviewed journal.

CONCLUSION

Our study will compare SUCA levels in different groups' psoriasis patients through network meta-analysis, and we believe our job is very meaningful.

ETHICS AND DISSEMINATION

Our study is a secondary study of the existing literature. So, ethical and dissemination approval is not required.

Phloretin ameliorates hyperuricemia-induced chronic renal dysfunction through inhibiting NLRP3 inflammasome and uric acid reabsorption

BACKGROUND

Hyperuricemia (HUA) is an important risk factor for renal diseases and contributes to renal fibrosis. It has been proved that phloretin has antioxidant and anti-inflammatory properties and could inhibit uric acid (UA) uptake in vitro. However, whether phloretin has a renal protective role in vivo remains unknown.

PURPOSE

This study aims to evaluate the therapeutic effect of phloretin on HUA-induced renal injury in mice and to reveal its underlying mechanism.

METHODS

Mice were induced hyperuricemic by oral gavage of adenine/potassium oxonate. The effects of phloretin on renal function, fibrosis, oxidative stress, inflammation, and UA metabolism in HUA mice were evaluated. The effect of phloretin on NLRP3 pathway was analyzed in human renal tubular cell lines (HK-2).

RESULTS

HUA mice showed renal dysfunction with increased renal fibrosis, inflammation and mitochondrial stress. By contrast, phloretin reduced the level of serum blood urea nitrogen (BUN), urinary albumin to creatinine ratio (UACR), tubular necrosis, extracellular matrix (ECM) deposition and interstitial fibroblasts in HUA mice. The renal infiltration of inflammatory cells, cytokines such as NOD-like receptor family pyrin domain containing 3 (NLRP3) and interleukin-1β (IL-1β) release, mitochondrial reactive oxygen species (ROS) and morphological lesions in HUA mice also decreased. Furthermore, phloretin partly inhibited renal glucose transporter 9 (GLUT9) and promoted urinary UA excretion in HUA mice. In vitro, phloretin suppressed the NLPR3 pathway under LPS or UA stimulation in HK-2 cells.

CONCLUSIONS

Phloretin could effectively attenuate UA-induced renal injury via co-inhibiting NLRP3 and UA reabsorption, and thus it might be a potential therapy to hyperuricemia-related renal diseases.

Relationships between Serum Uric Acid, Malondialdehyde Levels, and Carotid Intima-Media Thickness in the Patients with Metabolic Syndrome

Oxidative stress is the major cause of atherosclerosis and cardiovascular diseases. This cross-sectional study is aimed at determining if parallel serum markers of oxidative stress are related to carotid intima-media thickness (IMT). We enrolled 134 participants with varied metabolic syndrome (Met-S) scores (zero, n = 21; one, n = 19; two, n = 27; three, n = 26; four, n = 25; five, n = 16). Biochemical profiles and potential oxidative stress biomarkers malondialdehyde (MDA) and uric acid were measured in fasting plasma. We found that carotid IMT positively correlated with both MDA and uric acid levels. Multivariate analysis revealed that both MDA (p < 0.05) and uric acid (p < 0.01) levels were significantly associated with carotid IMT in participants whose Met-S scores were ≥1 or ≥2. However, only uric acid (p < 0.01) levels were positively associated with carotid IMT in patients with metabolic syndrome. Linear regression model analysis revealed that the prediction accuracies for carotid IMT from MDA combined with uric acid and from a combination of MDA, uric acid, and Met-S score were 0.176 and 0.237, respectively. These were better than the predication accuracies from MDA (r ² = 0.075) and uric acid (r ² = 0.148) individually. These results suggest that measuring uric acid levels along with MDA biomarkers and Met-S scores may be a promising step in the development of an effective model for monitoring the severity of carotid IMT and atherosclerosis in the patients with metabolic syndrome.

Structure-based design of a hyperthermostable AgUricase for hyperuricemia and gout therapy

Arthrobacter globiformis Uricase (AgUricase) is a homotetrameric uricase with the potential for therapeutic use in treating hyperuricemia-related diseases. To achieve sufficient therapeutic effects, it is essential for this enzyme to have high thermostability and long half-life in physiological condition. To improve the thermostability of this enzyme, we introduced a series of cysteine pair mutations into the AgUricase subunits based on its structural model and studied the thermostability of the mutant enzymes with introduced disulfide bridges. Two intersubunit cysteine pair mutations, K12C-E286C and S296C-S296C, were found to markedly increase the melting temperatures of the corresponding mutant enzymes compared with WT AgUricase. The crystal structure of the K12C-E286C mutant at 1.99 Å resolution confirmed the formation of a distinct disulfide bond between the two subunits in the dimer. Structural analysis and biochemical data revealed that the C-terminal loop of AgUricase was flexible, and its interaction with neighboring subunits was required for the stability of the enzyme. We introduced an additional intersubunit K244C-C302 disulfide bond based on the crystal structure of the K12C-E286C mutant and confirmed that this additional disulfide bond further stabilized the flexible C-terminal loop and improved the thermostability of the enzyme. Disulfide cross-linking also protected AgUricase from protease digestion. Our studies suggest that the introduction of disulfide bonds into proteins is a potential strategy for enhancing the thermostability of multimeric proteins for medical applications.