Gout

Association between combined exposure to ambient air pollutants, genetic risk, and incident gout risk: A prospective cohort study in the UK Biobank

BACKGROUND

Limited research has been conducted on the association between long-term exposure to air pollutants and the incidence of gout.

OBJECTIVES

This study aims to assess the individual and combined effects of prolonged exposure to five air pollutants (NO2, NOx, PM10, PMcoarse and PM2.52) on the incidence of gout among 458,884 initially gout-free participants enrolled in the UK Biobank.

METHODS

Employing a land use regression model, we utilized an estimation method to ascertain the annual concentrations of the five air pollutants. Subsequently, we devised a weighted air pollution score to facilitate a comprehensive evaluation of exposure. The Cox proportional hazards model was utilized to investigate the association between ambient air pollution and gout risk. Interaction and stratification analyses were conducted to evaluate age, sex, BMI, and genetic predisposition as potential effect modifiers in the air pollution-gout relationship. Furthermore, mediation analyses were conducted to explore the potential involvement of biomarkers in mediating the association between air pollution and gout.

RESULTS

Over a median follow-up time of 12.0 years, 7,927 cases of gout were diagnosed. Significant associations were observed between the risk of gout and a per IQR increase in NO2 (HR3: 1.05, 95 % CI4: 1.02-1.08, p = 0.003), NOx (HR: 1.04, 95 % CI: 1.01-1.06, p = 0.003), and PM2.5 (HR: 1.03, 95 % CI: 1.00-1.06, p = 0.030). Per IQR increase in the air pollution score was associated with an elevated risk of gout (p = 0.005). Stratified analysis revealed a significant correlation between the air pollution score and gout risk in participants ≥60 years (HR: 1.05, 95 % CI: 1.02-1.09, p = 0.005), but not in those <60 years (p = 0.793), indicating a significant interaction effect with age (p-interaction=0.009). Mediation analyses identified five serum biomarkers (SUA:15.87 %, VITD: 5.04 %, LDLD: 3.34 %, GGT: 1.90 %, AST: 1.56 %5) with potential mediation effects on this association.

CONCLUSIONS

Long-term exposure to air pollutants, particularly among the elderly population, is associated with an increased risk of gout. The underlying mechanisms of these associations may involve the participation of five serum biomarkers.

Discovery of digallic acid as XOD/URAT1 dual target inhibitor for the treatment of hyperuricemia

The development of XOD/URAT1 dual target inhibitors has emerged as a promising therapeutic strategy for the management of hyperuricemia. Here, through virtual screening, we have identified digallic acid as a novel dual target inhibitor of XOD/URAT1 and subsequently evaluated its pharmacological properties, pharmacokinetics, and toxicities. Digallic acid inhibited URAT1 with an IC50 of 5.34 ± 0.65 μM, which is less potent than benzbromarone (2.01 ± 0.36 μM) but more potent than lesinurad (10.36 ± 1.23 μM). Docking and mutation analysis indicated that residues S35, F241 and R477 of URAT1 confer a high affinity for digallic acid. Digallic acid inhibited XOD with an IC50 of 1.04 ± 0.23 μM. Its metabolic product, gallic acid, inhibited XOD with an IC50 of 0.91 ± 0.14 μM. Enzyme kinetic studies indicated that both digallic acid and gallic acid act as mixed-type XOD inhibitors. It shares the same binding mode as digallic acid, and residues E802, R880, F914, T1010, N768 and F1009 contribute to their high affinity. The anion group (carboxyl) of digallic acid contribute significantly to its inhibition activity on both XOD and URAT1 as indicated by docking analysis. Remarkably, at a dosage of 10 mg/kg in vivo, digallic acid exhibited a stronger urate-lowering and uricosuric effect compared to the positive drug benzbromarone and lesinurad. Pharmacokinetic study indicated that digallic acid can be hydrolyzed into gallic acid in vivo and has a t1/2 of 0.77 ± 0.10 h. Further toxicity evaluation indicated that digallic acid exhibited no obvious renal toxicity, as reflected by CCK-8, biochemical analysis (CR and BUN) and HE examination. The findings of our study can provide valuable insights for the development of XOD/URAT1 dual target inhibitors, and digallic acid deserves further investigation as a potential anti-hyperuricemic drug.

Analyzing chemical composition of Sargentodoxae caulis water extract and their hypouricemia effect in hyperuricemic mice

Hyperuricemia (HUA) is a metabolic disease characterized by the increase of serum uric acid (UA) level. Sargentodoxae Caulis (SC) is a commonly used herbal medicine for the treatment of gouty arthritis, traumatic swelling, and rheumatic arthritis in clinic. In this study, a total of fifteen compounds were identified in SC water extract using UHPLC-Q-TOF-MS/MS, including three phenolic acids, seven phenolic glycosides, four organic acids, and one lignan. Then, to study the hypouricemia effect of SC, a HUA mouse model was induced using a combination of PO, HX, and 20% yeast feed. After 14 days of treatment with the SC water extract, the levels of serum UA, creatinine (CRE), blood urea nitrogen (BUN) were reduced significantly, and the organ indexes were restored, the xanthine oxidase (XOD) activity were inhibited as well. Meanwhile, SC water extract could ameliorate the pathological status of kidneys and intestine of HUA mice. Additionally, quantitative real-time PCR (qRT-PCR) and western blotting results showed that SC water extract could increase the expression of ATP binding cassette subfamily G member 2 (ABCG2), organic cation transporter 1 (OCT1), organic anion transporter 1 (OAT1) and organic anion transporter 3 (OAT3), whereas decrease the expression of glucose transporter 9 (GLUT9). This study provided a data support for the clinical application of SC in the treatment of HUA.

Comparative Risk of Gout Flares When Initiating or Escalating Various Urate-Lowering Therapy: A Systematic Review With Network Meta-Analysis

OBJECTIVE

We systematically examined comparative gout flare risk after initiation or escalation of different urate-lowering therapies (ULTs), comparative flare risk with and without concomitant flare prophylaxis, adverse event rates associated with flare prophylaxis, and optimal duration of flare prophylaxis.

METHODS

We searched the Medline, Embase, Web of Science, and Cochrane databases and clinical trial registries from inception to November 2021 for trials investigating adults with gout initiating or escalating ULT. We performed random effects network meta-analyses and calculated risk ratios (RRs) between treatments. Bias was assessed using the revised Cochrane risk-of-bias tool.

RESULTS

We identified 3,775 records, of which 29 publications (27 trials) were included. When compared to placebo plus prophylaxis, the RR of flares ranged from 1.08 (95% confidence interval [CI] 0.87-1.33) for febuxostat 40 mg plus prophylaxis to RR 2.65 [95% CI 1.58-4.45] for febuxostat 80 mg plus lesinurad 400 mg plus prophylaxis. Compared to ULT alone, the RR of flares was lower for ULT plus rilonacept 160 mg (RR 0.35 [95% CI 0.25-0.50]), ULT plus rilonacept 80 mg (RR 0.43 [95% CI 0.31-0.60]) and ULT plus colchicine (RR 0.50 [95% CI 0.35-0.72]). There was limited evidence for other flare prophylaxis and on prophylaxis harms and optimal duration. Primarily because of missing outcome data and bias in the selection of reported results, 71.4% and 63.4% of studies were assessed as high risk of bias for flares and adverse events, respectively.

CONCLUSION

The RR of flares when introducing ULT varies depending on ULT drug and dosing strategies. There were limited data on ULT escalation. Flare prophylaxis with colchicine and rilonacept reduces flare incidence. More research is required on the harms and optimal duration of prophylaxis.

Hydrogel Nanoparticles Enable Nucleation Barrier Regulation and Ion Anchoring as an Alternative Pathway for Monosodium Urate Monohydrate Crystallization Control

Gout flare-up, commonly resulting from monosodium urate monohydrate (MSUM) crystallization, has led to painful inflammatory arthritis among hundreds of millions of people. Herein, a kind of hydrogel nanoparticles (HNPs) with specific properties was developed, aimed at providing a promising pathway for MSUM crystallization control. The experimental and molecular dynamics simulation results synchronously indicate that the fabricated HNPs achieve efficient inhibition of MSUM crystallization governed by the mechanism of "host-guest interaction" even under very low-dose administration. HNPs as the host dispersed in the hyperuricemic model effectively lift the relative heterogeneous nucleation barrier of the MSUM crystal and hinder solute aggregation with strong electronegativity and hydrophobicity. The initial appearance of MSUM crystals was then delayed from 94 to 334 h. HNPs as the guest on the surface of the formed crystal can decelerate the growth rate by anchoring ions and occupying the active sites on the surface, and the terminal yield of the MSUM crystal declined to less than 1% of the control group. The good biocompatibility of HNPs (cell viability > 94%) renders it possible for future clinical applications. This study can guide the rational design of inhibitory nanomaterials and the development of their application in the control of relevant pathological crystallization.

Correlation between remnant cholesterol and hyperuricemia in patients with type 2 diabetes mellitus: a cross-sectional study

BACKGROUND

Remnant cholesterol (RC) has been known as an important factor for the assessment of the metabolic syndrome (Mets) risk. However, the correlation between RC and hyperuricemia (HUA) in type 2 diabetes mellitus (T2DM) remains unclear. This study aims to explore the correlation between RC and HUA in patients with T2DM.

METHODS

A total of 2956 patients with T2DM admitted to the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University from 2020 to 2022 were included. The correlation between RC and HUA was evaluated with Spearman's correlation, multiple logistic regression, subgroup analyses, receiver operating characteristic (ROC) curves analyses and generalized smooth curve fitting. Total cholesterol (TC) < 5.18mmol/L was defined as normal TC.

RESULTS

RC was correlated with uric acid in patients with T2DM (Spearman's correlation coefficient = 0.279, P < 0.001). According to the multiple logistic regression analyses, there was an independent positive correlation between RC and HUA (OR = 1.63, 95%CI = 1.40, 1.90). In addition, a non-linear correlation between RC and HUA was identified. The area under the ROC curve (AUC) of RC (0.658, 95%CI = 0.635, 0.681) was the largest compared with those of low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and TC. Subgroup analyses showed a more significant positive correlation among females or normal TC groups.

CONCLUSION

Elevated RC is correlated with HUA in patients with T2DM significantly and positively. RC is better in its predictability for HUA than that of conventional lipid indexes.

Bone and Joint-on-Chip Platforms: Construction Strategies and Applications

Organ-on-a-chip, also known as "tissue chip," is an advanced platform based on microfluidic systems for constructing miniature organ models in vitro. They can replicate the complex physiological and pathological responses of human organs. In recent years, the development of bone and joint-on-chip platforms aims to simulate the complex physiological and pathological processes occurring in human bones and joints, including cell-cell interactions, the interplay of various biochemical factors, the effects of mechanical stimuli, and the intricate connections between multiple organs. In the future, bone and joint-on-chip platforms will integrate the advantages of multiple disciplines, bringing more possibilities for exploring disease mechanisms, drug screening, and personalized medicine. This review explores the construction and application of Organ-on-a-chip technology in bone and joint disease research, proposes a modular construction concept, and discusses the new opportunities and future challenges in the construction and application of bone and joint-on-chip platforms.

Investigating the effects of rare ginsenosides on hyperuricemia and associated sperm damage via nontargeted metabolomics and gut microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

In ancient times, ginseng was used for hyperuricemia treatment as described in the classic traditional Chinese medical text Shang Han Lun. Recent studies have shown that common ginsenosides and rare ginsenosides (RGS) are the main active compounds in ginseng. RGS have higher activity and are less studied in the treatment of hyperuricemia.

AIM OF THE STUDY

To determine whether RGS prevents and ameliorates potassium oxonate(PO)-induced hyperuricemia and concomitant spermatozoa damage in mice and the possible underlying mechanisms.

MATERIALS AND METHODS

Potassium oxonate (PO, 300 mg/kg) induced hyperuricemia in mice via the oral administration of RGS (50, 100, or 200 mg/kg) or allopurinol (ALL, 5 mg/kg) for 35 days. Uric acid (UA) and xanthine oxidase (XO) levels were measured to assess the degree of histopathological damage in the liver, kidney, and testis, and renal creatinine (CRE), urea nitrogen (BUN), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and inflammatory factor (IL-1β) levels were measured to calculate the sperm density. Mechanisms were also explored based on blood and urine metabolomics and the gut microbiota.

RESULTS

In this study, we demonstrated that RGS containing Rg3, Rk1, Rg6, and Rg5 could reduce serum UA levels, inhibit serum and hepatic XO activity, reduce renal CRE and BUN levels, further restore renal SOD and GSH activities, reduce the accumulation of MDA in the kidneys, and attenuate the production of renal IL-1β. RGS was able to restore sperm density. Metabolomic analysis revealed that RGS improved sphingolipid metabolism, pyrimidine metabolism, and other metabolic pathways. 16S rDNA sequencing revealed that RGS could increase gut microbial diversity, restore the Firmicutes/Bacteroidetes (F/B) ratio, and adjust the intestinal microbial balance. Spearman's correlation analysis revealed a correlation between differentially metabolites and the gut microbiota. Lactobacillus and Akkermansia are the core genera.

CONCLUSION

RGS can be a candidate for the prevention and amelioration of hyperuricemia and concomitant sperm damage. Its mechanism of action is closely related to sphingolipid metabolism, pyrimidine metabolism, and the modulation of gut microbiota, such as Lactobacillus and Akkermansia.

Nonlinear association of triglyceride-glucose index with hyperuricemia in US adults: a cross-sectional study

BACKGROUND

Despite abundant evidence on the epidemiological risk factors of metabolic diseases related to hyperuricemia, there is still insufficient evidence regarding the nonlinear relationship between triglyceride-glucose (TyG) index and hyperuricemia. Thus, the purpose of this research is to clarify the nonlinear connection between TyG and hyperuricemia.

METHODS

From 2011 to 2018, a cross-sectional study was carried out using data from the National Health and Nutrition Examination Survey (NHANES). This study had 8572 participants in all. TyG was computed as Ln [triglycerides (mg/dL) × fasting glucose (mg/dL)/2]. The outcome variable was hyperuricemia. The association between TyG and hyperuricemia was examined using weighted multiple logistic regression, subgroup analysis, generalized additive models, smooth fitting curves, and two-piecewise linear regression models.

RESULTS

In the regression model adjusting for all confounding variables, the OR (95% CI) for the association between TyG and hyperuricemia was 2.34 (1.70, 3.21). There is a nonlinear and reverse U-shaped association between TyG and hyperuricemia, with a inflection point of 9.69. The OR (95% CI) before the inflection point was 2.64 (2.12, 3.28), and after the inflection point was 0.32 (0.11, 0.98). The interaction in gender, BMI, hypertension, and diabetes analysis was statistically significant.

CONCLUSION

Additional prospective studies are required to corroborate the current findings, which indicate a strong positive connection between TyG and hyperuricemia among adults in the United States.

Astilbin inhibited neutrophil extracellular traps in gouty arthritis through suppression of purinergic P2Y6 receptor

BACKGROUND

Gouty arthritis (GA), a common inflammatory condition triggered by monosodium urate crystal accumulation, often necessitates safer treatment alternatives due to the limitations of current therapies. Astilbin, a flavonoid from Smilax glabra Roxb, has demonstrated potential in traditional Chinese medicine for its anti-inflammatory properties. However, the anti-GA effect and its underlying mechanism have not been fully elucidated.

PURPOSE

This study aimed to investigate the therapeutic potential of astilbin in GA, focusing on its effects on neutrophil extracellular traps (NETs), as well as the potential molecular target of GA both in vitro and in vivo.

STUDY DESIGN

Firstly, astilbin inhibited the citrullinated histone H3 (Cit h3) protein levels and reduced the NETs formation in neutrophils stimulated by monosodium urate (MSU). Secondly, we wondered the effect of astilbin on migration of neutrophils and dimethyl-sulfoxide (DMSO)-differentiated HL-60 (dHL-60) cells under the stimulation of MSU. Then, the effect of astilbin on suppressing NETs through purinergic P2Y6 receptor (P2Y6R) and Interlukin-8 (IL-8)/ CXC chemokine receptor 2 (CXCR2) pathway was investigated. Also, the relationship between P2Y6R and IL-8/CXCR2 was explored in dHL-60 cells under stimulation of MSU. Finally, we testified the effect of astilbin on reducing NETs in GA through suppressing P2Y6R and then down-regulating IL-8/CXCR2 pathway.

METHODS

MSU was used to induce NETs in neutrophils and dHL-60 cells. Real-time formation of NETs and migration of neutrophils were monitored by cell living imaging with or without MSU. Then, the effect of astilbin on NETs formation, P2Y6R and IL-8/CXCR2 pathway were detected by immunofluorescence (IF) and western blotting. P2Y6R knockdown dHL-60 cells were established by small interfering RNA to investigate the association between P2Y6R and IL-8/CXCR2 pathway. Also, plasmid of P2Y6R was used to overexpress P2Y6R in dHL-60 cells, which was employed to explore the role of P2Y6R in astilbin inhibiting NETs. Within the conditions of knockdown and overexpression of P2Y6R, migration and NETs formation were assessed by transmigration assay and IF staining, respectively. In vivo, MSU-induced GA mice model was established to assess the effect of astilbin on inflammation by haematoxylin-eosin and ELISA. Additionally, the effects of astilbin on neutrophils infiltration, NETs, P2Y6R and IL-8/CXCR2 pathway were analyzed by IF, ELISA, immunohistochemistry (IHC) and western blotting.

RESULTS

Under MSU stimulation, astilbin significantly suppressed the level of Cit h3 and NETs formation including the fluorescent expressions of Cit h3, neutrophils elastase, myeloperoxidase, and intra/extracellular DNA. Also, results showed that MSU caused NETs release in neutrophils as well as a trend towards recruitment of dHL-60 cells to MSU. Astilbin could markedly decrease expressions of P2Y6R and IL-8/CXCR2 pathway which were upregulated by MSU. By silencing P2Y6R, the expression of IL-8/CXCR2 pathway and migration of dHL-60 cells were inhibited, leading to the suppression of NETs. These findings indicated the upstream role of P2Y6R in the IL-8/CXCR2 pathway. Moreover, overexpression of P2Y6R was evidently inhibited by astilbin, causing a downregulation in IL-8/CXCR2 pathway, migration of dHL-60 cells and NETs formation. These results emphasized that astilbin inhibited the IL-8/CXCR2 pathway primarily through P2Y6R. In vivo, astilbin administration led to marked reductions in ankle swelling, inflammatory infiltration as well as neutrophils infiltration. Expressions of P2Y6R and IL-8/CXCR2 pathway were evidently decreased by astilbin and P2Y6R inhibitor MRS2578 either alone or in combination. Also, astilbin and MRS2578 showed notable effect on reducing MSU-induced NETs formation and IL-8/CXCR2 pathway whether used alone or in combination, parallelly demonstrating that astilbin decreased NETs formation mainly through P2Y6R.

CONCLUSION

This study revealed that astilbin suppressed NETs formation via downregulating P2Y6R and subsequently the IL-8/CXCR2 pathway, which evidently mitigated GA induced by MSU. It also highlighted the potential of astilbin as a promising natural therapeutic for GA.

2023 EULAR recommendations on imaging in diagnosis and management of crystal-induced arthropathies in clinical practice

OBJECTIVE

To formulate evidence-based recommendations and overarching principles on the use of imaging in the clinical management of crystal-induced arthropathies (CiAs).

METHODS

An international task force of 25 rheumatologists, radiologists, methodologists, healthcare professionals and patient research partners from 11 countries was formed according to the EULAR standard operating procedures. Fourteen key questions on the role of imaging in the most common forms of CiA were generated. The CiA assessed included gout, calcium pyrophosphate deposition disease and basic calcium phosphate deposition disease. Imaging modalities included conventional radiography, ultrasound, CT and MRI. Experts applied research evidence obtained from four systematic literature reviews using MEDLINE, EMBASE and CENTRAL. Task force members provided level of agreement (LoA) anonymously by using a Numerical Rating Scale from 0 to 10.

RESULTS

Five overarching principles and 10 recommendations were developed encompassing the role of imaging in various aspects of patient management: making a diagnosis of CiA, monitoring inflammation and damage, predicting outcome, response to treatment, guided interventions and patient education. Overall, the LoA for the recommendations was high (8.46-9.92).

CONCLUSIONS

These are the first recommendations that encompass the major forms of CiA and guide the use of common imaging modalities in this disease group in clinical practice.

Identification of SOCS3 and PTGS2 as new biomarkers for the diagnosis of gout by cross-species comprehensive analysis

Background

Gout is the most common inflammatory arthritis in adults. Gout is an arthritic disease caused by the deposition of monosodium urate crystal (MSU) in the joints, which can lead to acute inflammation and damage adjacent tissue. Hyperuricemia is the main risk factor for MSU crystal deposition and gout. With the increasing burden of gout disease, the identification of potential biomarkers and novel targets for diagnosis is urgently needed.

Methods

For the analysis of this subject paper, we downloaded the human gout data set GSE160170 and the gout mouse model data set GSE190138 from the GEO database. To obtain the differentially expressed genes (DEGs), we intersected the two data sets. Using the cytohubba algorithm, we identified the key genes and enriched them through GO and KEGG. The gene expression trends of three subgroups (normal control group, intermittent gout group and acute gout attack group) were analyzed by Series Test of Cluster (STC) analysis, and the key genes were screened out, and the diagnostic effect was verified by ROC curve. The expression of key genes in dorsal root nerve and spinal cord of gout mice was analyzed. Finally, the clinical samples of normal control group, hyperuricemia group, intermittent gout group and acute gout attack group were collected, and the expression of key genes at protein level was verified by ELISA.

Result

We obtained 59 co-upregulated and 28 co-downregulated genes by comparing the DEGs between gout mouse model data set and human gout data set. 7 hub DEGs(IL1B, IL10, NLRP3, SOCS3, PTGS2) were screened out via Cytohubba algorithm. The results of both GO and KEGG enrichment analyses indicate that 7 hub genes play a significant role in regulating the inflammatory response, cytokine production in immune response, and the TNF signaling pathway. The most representative hub genes SOCS3 and PTGS2 were screened out by Series Test of Cluster, and ROC analysis results showed the AUC values were both up to 1.000. In addition, we found that PTGS2 expression was significantly elevated in the dorsal root ganglia and spinal cord in monosodium urate(MSU)-induced gout mouse model. The ELISA results revealed that the expression of SOCS3 and PTGS2 was notably higher in the acute gout attack and intermittent gout groups compared to the normal control group. This difference was statistically significant, indicating a clear distinction between the groups.

Conclusion

Through cross-species comprehensive analysis and experimental verification, SOCS3 and PTGS2 were proved to be new biomarkers for diagnosing gout and predicting disease progression.

Review: The Role of Dual-Energy Computed Tomography in Detecting Monosodium Urate Deposits in Vascular Tissues

PURPOSE OF REVIEW

To highlight novel findings in the detection of monosodium urate deposits in vessels using dual energy computed tomography, and to discuss the potential clinical implications for gout and hyperuricemia patients.

RECENT FINDINGS

Gout is an independent risk factor for cardiovascular disease. However, classical risk calculators do not take into account these hazards, and parameters to identify patients at risk are lacking. Monosodium urate measured by dual energy computed tomography is a well-established technology for the detection and quantification of monosodium urate deposits in peripheral joints and tendons. Recent findings also suggest its applicability to identify vascular urate deposits. Dual energy computed tomography is a promising tool for detection of cardiovascular monosodium urate deposits in gout patients, to better delineate individuals at increased risk for cardiovascular disease.

Investigating the Impact of Gut Microbiota on Gout Through Mendelian Randomization

Background

The relationship between gout and gut microbiota has attracted significant attention in current research. However, due to the diverse range of gut microbiota, the specific causal effect on gout remains unclear. This study utilizes Mendelian randomization (MR) to investigate the causal relationship between gut microbiota and gout, aiming to elucidate the underlying mechanism of microbiome-mediated gout and provide valuable guidance for clinical prevention and treatment.

Materials and Methods

The largest genome-wide association study meta-analysis conducted by the MiBioGen Consortium (n=18,340) was utilized to perform a two-sample Mendelian randomization investigation on aggregate statistics of intestinal microbiota. Summary statistics for gout were utilized from the data released by EBI. Various methods, including inverse variance weighted, weighted median, weighted model, MR-Egger, and Simple-mode, were employed to assess the causal relationship between gut microbiota and gout. Reverse Mendelian randomization analysis revealed a causal association between bacteria and gout in forward Mendelian randomization analysis. Cochran's Q statistic was used to quantify instrumental variable heterogeneity.

Results

The inverse variance weighted estimation revealed that Rikenellaceae exhibited a slight protective effect on gout, while the presence of Ruminococcaceae UCG_011 is associated with a marginal increase in the risk of gout. According to the reverse Mendelian Randomization results, no significant causal relationship between gout and gut microbiota was observed. No significant heterogeneity of instrumental variables or level pleiotropy was detected.

Conclusion

Our MR analysis revealed a potential causal relationship between the development of gout and specific gut microbiota; however, the causal effect was not robust, and further research is warranted to elucidate its underlying mechanism in gout development. Considering the significant association between diet, gut microbiota, and gout, these findings undoubtedly shed light on the mechanisms of microbiota-mediated gout and provide new insights for translational research on managing and standardizing treatment for this condition.

Sirt1 inhibits macrophage polarization and inflammation in gouty arthritis by inhibiting the MAPK/NF-κB/AP-1 pathway and activating the Nrf2/HO-1 pathway

OBJECTIVE AND DESIGN

To elucidate Sirt1's role in gouty arthritis inflammation and its potential mechanisms.

MATERIAL

Constructed murine models of gouty arthritis and conducted THP-1 cell experiments.

TREATMENT

1 mg of MSU crystals injected into mice ankle joints for a 72-h intervention. After a 3-h pre-treatment with Sirt1-specific inhibitor (EX527) and agonist (SRT2104), inflammation was induced for 21 h using lipopolysaccharide (LPS) plus MSU crystals.

METHODS

We assessed gouty arthritis severity through joint inflammation index, swelling, and hematoxylin and eosin (H&E) staining, and measured CD68 mononuclear macrophages and Sirt1 expression in synovial tissue via immunohistochemistry. ELISA, NO assay, RT-qPCR, Flow cytometry, and Western blot were utilized to examine macrophage inflammatory factors, polarization, reactive oxygen species(ROS), MAPK/NF-κB/AP-1 and Nrf2/HO-1 pathways proteins.

RESULTS

Significant joint swelling, synovial tissue edema, and inflammatory cell infiltration were observed. CD68 mononuclear macrophages and Sirt1 expression were elevated in synovium. Sirt1 activation decreased inflammatory factors, M1 polarization, and ROS generation. Sirt1 activation reduced p38/JNK phosphorylation, thereby inhibiting downstream NF-κB p65/AP-1 and enhancing Nrf2/HO-1, thus suppressing inflammation.

CONCLUSIONS

Sirt1 alleviates M1 macrophage polarization and inflammation in gouty arthritis by inhibiting the MAPK/NF-κB/AP-1 pathway and activating the Nrf2/HO-1 pathway. Thus, activating Sirt1 may provide a new therapeutic target for gouty arthritis.

Signaling pathways in uric acid homeostasis and gout: From pathogenesis to therapeutic interventions

Uric acid is a product of purine degradation, and uric acid may have multiple physiologic roles, including the beneficial effects as an antioxidant and neuroprotector, maintenance of blood pressure during low salt ingestion, and modulation of immunity. However, overproduction of metabolic uric acid, and/or imbalance of renal uric acid secretion and reabsorption, and/or underexcretion of extrarenal uric acid, e.g. gut, will contribute to hyperuricemia, which is a common metabolic disease. Long-lasting hyperuricemia can induce the formation and deposition of monosodium urate (MSU) crystals within the joints and periarticular structures. MSU crystals further induce an acute, intensely painful, and sterile inflammation conditions named as gout by NLRP3 inflammasome-mediated cleavage of pro-IL-1β to bioactive IL-1β. Moreover, hyperuricemia and gout are associated with multiple cardiovascular and renal disorders, e.g., hypertension, myocardial infarction, stroke, obesity, hyperlipidemia, type 2 diabetes mellitus and chronic kidney disease. Although great efforts have been made by scientists of modern medicine, however, modern therapeutic strategies with a single target are difficult to exert long-term positive effects, and even some of these agents have severe adverse effects. The Chinese have used the ancient classic prescriptions of traditional Chinese medicine (TCM) to treat metabolic diseases, including gout, by multiple targets, for more than 2200 years. In this review, we discuss the current understanding of urate homeostasis, the pathogenesis of hyperuricemia and gout, and both modern medicine and TCM strategies for this commonly metabolic disorder. We hope these will provide the good references for treating hyperuricemia and gout.

Estimation of the spatial pattern of gout prevalence across China by wastewater-based epidemiology

Gout is a metabolic arthritis caused by hyperuricemia. In recent years, the prevalence of gout has been increased significantly in China due to the improvement of the living standards, and gout has become another common metabolic disease following diabetes mellitus. Gout severely affects the health status and life quality of human. In order to monitor the near real-time prevalence of gout, a wastewater-based epidemiology (WBE) approach was carried out in 257 Chinese cities using febuxostat as the biomarker. Febuxostat in wastewater was measured by a LC-MS/MS method with satisfactory results of method validation. The average concentration of febuxostat in wastewater was 53.05 ± 31.76 ng/L, with the estimated per capita consumption of 124.40 ± 73.37 mg/day/1000 inhabitant. The calculated prevalence of febuxostat was 0.41 % ± 0.24 %, and the prevalence of gout was finally estimated to be 1.30 % ± 0.77 % (0.60 % to 2.11 %), which was nearly consistent with value of 1.10 % obtained from the Guideline for the diagnosis and management of hyperuricemia and gout in China (2019). The results indicated that the febuxostat-based WBE approach might be reasonable to assess the near real-time gout prevalence in China.

Association between low-density lipoprotein cholesterol levels and serum uric acid to serum creatinine ratio in Chinese male gout patients

This study aimed to evaluate the association between low-density lipoprotein cholesterol (LDL-C) and serum uric acid to serum creatinine (SUA/SCr) ratio in male gout patients at different BMIs. This real-world study included 956 male gout patients aged 18-83 years. We retrospectively analyzed the medical records of Chinese male gout patients from 2017 to 2019. The correlation between LDL-C and SUA/SCr was tested after adjusting for confounding factors. We found a nonlinear relationship between LDL-C and SUA/SCr in the whole study population. Stratification analysis showed that there was actually a nonlinear relationship between LDL-C and SUA/SCr in men with a BMI of 24-28, the inflection point of LDL-C was 1.8 mmol/L, when LDL-C was greater than 1.8 mmol/L, there was a positive correlation between LDL-C levels and SUA/SCr (β = 0.67, 95% CI 0.35-0.98, P < 0.001). Moreover, LDL-C showed a significant positive correlation with SUA/SCr with a BMI of 28 or greater (β = 0.30, 95% CI 0.05-0.55, P = 0.019). However, no association was found between LDL-C and SUA/SCr with a BMI of less than 24 (β = 0.42, 95% CI - 0.03-0.86, P = 0.070). LDL-C levels were associated with SUA/SCr in Chinese male gout patients, but this correlation appeared inconsistent among different BMIs. Our findings suggest that LDL-C levels may be more noteworthy in overweight and/or obese male gout patients.

Unveiling potent Schiff base derivatives with selective xanthine oxidase inhibition: In silico and in vitro approach

This research describes the synthesis by an environmentally-friendly method, microwave irradiation, development and analysis of three novel and one previously identified Schiff base derivative as a potential inhibitor of bovine xanthine oxidase (BXO), a key enzyme implicated in the progression of gout. Meticulous experimentation revealed that these compounds (10, 9, 4, and 7) have noteworthy inhibitory effects on BXO, with IC50 values ranging from 149.56 µM to 263.60 µM, indicating their good efficacy compared to that of the standard control. The validation of these results was further enhanced through comprehensive in silico studies, which revealed the pivotal interactions between the inhibitors and the catalytic sites of BXO, with a particular emphasis on the imine group (-C = N-) functionalities. Intriguingly, the compounds exhibiting the highest inhibition rates also showcase advantageous ADMET profiles, alongside encouraging initial assessments via PASS, hinting at their broad-spectrum potential. The implications of these findings are profound, suggesting that these Schiff base derivatives not only offer a new vantage point for the inhibition of BXO but also hold considerable promise as innovative therapeutic agents in the management and treatment of gout, marking a significant leap forward in the quest for more effective gout interventions.

Superiority of Low-Dose Benzbromarone Add-On to Low-Dose Febuxostat Compared With Febuxostat Monotherapy in Gout With Combined-Type Hyperuricemia

OBJECTIVE

There is an unmet need for simpler urate-lowering therapy (ULT) regimens that achieve the serum urate target and improve the overall quality of gout care. We report a comparative effectiveness trial of febuxostat monotherapy versus benzbromarone add-on to low-dose febuxostat in gout specifically with combined renal urate underexcretion and overload.

METHODS

A prospective randomized trial was conducted on patients with combined-type hyperuricemia and estimated glomerular filtration rate >60 mL/min/1.73 m2 1:1 randomly assigned to febuxostat and benzbromarone combination therapy (initially febuxostat at 20 mg/day, with benzbromarone at 25 mg/day added onto 20 mg/day of febuxostat if not at target) or febuxostat monotherapy (initially 20 mg/day, escalating to 40 mg/day if not at target). The primary end point at 12 weeks was the proportion achieving a serum urate (SU) level <360 μmol/L. Other outcomes included altered liver and kidney function, new-onset urolithiasis, and gout flares.

RESULTS

There were 250 participants randomized; 219 completed 12-week treatment. More patients in the febuxostat and benzbromarone combination group achieved the SU target compared to patients in the febuxostat monotherapy group (75.5% vs 47.7%; odds ratio 3.37 [95% confidence interval 1.90-5.98]). Safety profiles were comparable between the two groups.

CONCLUSION

Simply adding on low-dose benzbromarone (25 mg/day) to low-dose (20 mg/day) febuxostat showed superior urate lowering compared to febuxostat monotherapy in gout with a combined-type hyperuricemia. For selected patients, expedited achievement of the SU target in more than 75% of patients using one titration step and low xanthine oxidase inhibitor and uricosuric doses is a potential alternative to standard ULT regimens.

Comparison of the efficacy and safety of benzbromarone and febuxostat in gout and hyperuricemia: a systematic review and meta-analysis

OBJECTIVE

Urate-lowering therapy (ULT) is widely recognized as the primary treatment for hyperuricemia and gout. Xanthine oxidase inhibitors (XOI), particularly febuxostat, have gained popularity as a frontline approach. However, the divergent efficacy and safety between febuxostat and the traditional ULT drug, benzbromarone, remain poorly understood. This knowledge gap necessitates a comprehensive analysis and evidence update to guide drug selection for physicians and patients.

METHOD

We conducted a systematic analysis by extracting relevant clinical studies from four medical literature databases. Forest plots, funnel plots, sensitivity analysis, Egger's test, and subgroup analysis were utilized to compare relevant indicators.

RESULTS

The advantages and disadvantages of the two drugs were evaluated based on various indicators such as serum uric acid (SUA), triglyceride (TG), urinary uric acid (UUA), white blood cell count (WBC), total cholesterol (TC), blood urea nitrogen (BUN), alanine aminotransferase (ALT), aspartate aminotransferase (AST), estimated glomerular filtration rate (eGFR), and serum creatinine (SC). Benzbromarone demonstrated better efficacy in rapidly reducing SUA levels and inhibiting inflammation for hyperuricemia and gout patients. Febuxostat was slightly less effective in lowering SUA, but there was no significant difference in its impact on liver and kidney function after long-term use.

CONCLUSION

This study highlights the superiority of benzbromarone in rapidly reducing SUA and inhibiting inflammation. Febuxostat shows comparable effects on liver and kidney function after long-term use. These findings provide valuable insights for clinicians and patients in drug selection. Key Points • Benzbromarone stands out as a highly effective treatment for hyperuricemia and gout, offering rapid reduction of serum uric acid levels and potent anti-inflammatory effects. • When it comes to long-term use, febuxostat demonstrates comparable effects on liver and kidney function. This provides reassurance for patients who require extended treatment duration. • Moreover, our study goes beyond previous research by presenting a more comprehensive and detailed analysis.

Efficacy and safety of Huzhang Granule, a compound Chinese herbal medicine, for acute gouty arthritis: A double-blind, randomized controlled trial

BACKGROUND

Acute gouty arthritis (AGA) is an inflammatory joint disease with a high prevalence. Typical medical interventions, including nonsteroidal anti-inflammatory drugs, colchicine and glucocorticoids, can have serious adverse reactions. Huzhang Granule (HZG), a compound Chinese herbal medicine, has been used to treat AGA for more than 30 years with satisfactory effects and no significant adverse reactions. However, the efficacy and safety of HZG in AGA patients remains unknown.

OBJECTIVE

The present investigation was designed to examine the efficacy and safety profile of HZG in managing AGA patients.

DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS

The current study was conducted as a noninferiority, randomized controlled clinical trial on 180 eligible enrolled participants. Participants were randomly assigned into the HZG and etoricoxib groups. Treatments were administered for 5 d, during which the HZG group received HZG and placebo etoricoxib, while the etoricoxib group received etoricoxib and placebo HZG in the same ratio (1:1).

MAIN OUTCOME MEASURES

The primary outcome was pain experienced by the patient in the gout-afflicted joint from days 2 to 5 of the treatment window. The pain level was measured via a visual analogue scale, ranging from 0 mm to 100 mm. The secondary outcomes comprised joint tenderness and swelling, reduction of inflammatory biomarkers, and the patient's and investigator's global evaluations of therapeutic response.

RESULTS

The mean reduction in pain was -51.22 mm (95% confidence interval [CI], [-53.42, -49.03] mm) for the HZG and -52.00 mm (95% CI, [-54.06, -49.94] mm) for the etoricoxib groups. The mean difference between the two groups was 0.78 mm (95% CI, [-2.25, 3.81] mm). All additional efficacy endpoints, covering decreased inflammation and pain relief, yielded compelling proof of noninferiority. Patients in the HZG group exhibited a comparatively lower rate of adverse events compared to those in the etoricoxib group (4.44% vs 13.33%; P ≤ 0.05).

CONCLUSION

HZG and etoricoxib groups demonstrated similar levels of analgesic effectiveness. The safety and efficacy of HZG indicates that it can be used as a potential therapeutic option for treating AGA.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2000036970). Please cite this article as: Wang H, Chen ST, Ding XJ, Kuai L, Hua L, Li X, Wang YF, Zhang M, Li B, Wang RP, Zhou M. Efficacy and safety of Huzhang Granule, a compound Chinese herbal medicine, for acute gouty arthritis: A double-blind, randomized controlled trial. J Integr Med. 2024; 22(3): 270-278.

Changes in Serum Urate Levels after Bariatric Surgery in Patients with Obesity: An Observational Study

BACKGROUND

Obesity is a risk factor for hyperuricemia and gout, while weight reduction can reduce urate levels. The aim of this study was to examine the effect of bariatric surgery on longitudinal serum urate levels.

METHODS

We performed a retrospective observational study of 283 patients who had undergone bariatric surgery [237 (83.7%) gastric bypass, 34 (12.0%) sleeve gastrectomy and 12 (4.2%) gastric banding] and were followed up for 2 years. The results shown represent mean (standard deviation).

RESULTS

Bariatric surgery was associated with significant reduction in serum urate from baseline level of 0.343 (0.086) mmol/L to 0.296 (0.076) mmol/L (p < 0.001) at 12 months and 0.286 (0.073) mmol/L (p < 0.001) at 24 months, including in men and women, and in patients with or without diabetes. Patients with elevated urate levels at baseline, who comprised 27.2% of the total cohort, achieved reduction in levels by 4 months.

CONCLUSION

Bariatric surgery leads to significant reduction in serum urate levels at 12 and 24 months. This could reduce incidence of gout and need for prophylactic medication(s).

Colorimetric and fluorometric determination of uric acid by a suspension-based assay using enzyme-immobilized micro-sized particles

Daily monitoring of serum uric acid levels is very important to provide appropriate treatment according to the constitution and lifestyle of individual hyperuricemic patients. We have developed a suspension-based assay to measure uric acid by adding a sample solution to the suspension containing micro-sized particles immobilized on uricase and horseradish peroxidase (HRP). In the proposed method, the mediator reaction of uricase, HRP, and uric acid produces resorufin from Amplex red. This resorufin is adsorbed onto enzyme-immobilized micro-sized particles simultaneously with its production, resulting in the red color of the micro-sized particles. The concentration of resorufin on the small surface area of the microscopic particles achieves a colorimetric analysis of uric acid with superior visibility. In addition, ethanol-induced desorption of resorufin allowed quantitative measurement of uric acid using a 96-well fluorescent microplate reader. The limit of detection (3σ) and RSD (n = 3) were estimated to be 2.2 × 10-2 μg/mL and ≤ 12.1%, respectively. This approach could also be applied to a portable fluorometer.

Metabolite-derived damage-associated molecular patterns in immunological diseases

Damage-associated molecular patterns (DAMPs) are typically derived from the endogenous elements of necrosis cells and can trigger inflammatory responses by activating DAMPs-sensing receptors on immune cells. Failure to clear DAMPs may lead to persistent inflammation, thereby contributing to the pathogenesis of immunological diseases. This review focuses on a newly recognized class of DAMPs derived from lipid, glucose, nucleotide, and amino acid metabolic pathways, which are then termed as metabolite-derived DAMPs. This review summarizes the reported molecular mechanisms of these metabolite-derived DAMPs in exacerbating inflammation responses, which may attribute to the pathology of certain types of immunological diseases. Additionally, this review also highlights both direct and indirect clinical interventions that have been explored to mitigate the pathological effects of these DAMPs. By summarizing our current understanding of metabolite-derived DAMPs, this review aims to inspire future thoughts and endeavors on targeted medicinal interventions and the development of therapies for immunological diseases.

Effects of stocking density on the homeostasis of uric acid and related liver and kidney functions in ducks

OBJECTIVE

Stocking density (SD) is an important issue in the poultry industry, which is related to the production performance, intestinal health and immune status. In the present study, the effects of SD on the metabolism and homeostasis of uric acid as well as the related functions of the liver and kidney in ducks were examined.

METHODS

A total of 360 healthy 56-day-old Shan-ma ducks were randomly divided into the low stocking density (n = 60, density = 5 birds/m2), medium stocking density (n = 120, density = 10 birds/m2) and high stocking density groups (HSD; n = 180, density = 15 birds/m2). Samples were collected in the 3rd, 6th, and 9th weeks of the experiment for analysis.

RESULTS

The serum levels of uric acid, lipopolysaccharide and inflammatory cytokines (interleukin-1β [IL-1β], IL-8, and tumor necrosis factor-α [TNF-α]) were increased significantly in the HSD group. Serious histopathological lesions could be seen in both the livers and kidneys in the HSD group in the 9th week. The mRNA expression levels of inflammatory cytokines (IL-8 and TNF-α) and related pathway components (toll-like receptor 4, myeloid differentiation primary response gene 88, and nuclear factor-κB) were increased significantly in both the livers and kidneys in the HSD group. The mRNA expression levels of enzymes (adenosine deaminase, xanthine oxidase, phosphoribosyl pyrophosphate amidotransferase, and phosphoribosyl pyrophosphate synthetase 1) related to the synthesis of uric acid increased significantly in the livers in the HSD group. However, the mRNA expression level of solute carrier family 2 member 9, which plays an important role in the excretion of uric acid by the kidney, was decreased significantly in the kidneys in the HSD group.

CONCLUSION

These results indicated that a higher SD could cause tissue inflammatory lesions in the liver and kidney and subsequently affect the metabolism and homeostasis of uric acid, and is helpful for guiding decisions related to the breeding and production of ducks.

Comparison of the therapeutic effects of febuxostat combined with a low-purine diet and allopurinol combined with a low-purine diet on the improvement of gout patients

OBJECTIVE

To compare the clinical efficacy of febuxostat combined with a low-purine diet versus allopurinol combined with a low-purine diet in the treatment of gout.

METHODS

In this prospective controlled trial, 98 gout patients admitted to our hospital from February 2021 to December 2022 were enrolled as study subjects. Patients were randomly assigned to the study group (febuxostat combined with a low-purine diet) and the control group (allopurinol combined with a low-purine diet), with 49 patients in each group. The therapeutic effect was evaluated based on joint function and serum uric acid levels after treatment, and classified into three levels: markedly effective, effective, and ineffective. The levels of inflammatory factors, including tumor necrosis factor-a (TNF-a), cytokine interleukin-1beta (IL-1β), and interleukin (IL)-18 (IL-18), were collected. The Numeric Rating Scale (NRS) was used to assess the degree of pain in patients. Clinical indicators before and 6 months after treatment were compared between the two groups.

RESULTS

There was no statistically significant difference in age and gender between the two groups. After 6 months of treatment, the effective rate in the study group (48 cases, 97.96%) was higher than that in the control group (42 cases, 85.71%), with a statistically significant difference (p = .027). At the same time, the study group had significantly lower levels of serum uric acid (162.39 μmol/L ± 17.23 μmol/L vs. S198.32 μmol/L ± 18.34 μmol/L, p < .001), creatinine (87.39 mmol/L ± 9.76 mmol/L vs. 92.18 mmol/L ± 9.27 mmol/L, p = .014), total cholesterol (3.65 mmol/L ± 0.65 mmol/L vs. 4.76 mmol/L ± 0.73 mmol/L, p < .001), and triglycerides (1.76 mmol/L ± 0.32 mmol/L vs. 2.28 mmol/L ± 0.41 mmol/L, p < .001) compared to the control group, with statistically significant differences (p < .05). After treatment, the levels of inflammatory factors and degree of pain in the study group were significantly lower than those in the control group (all p < .05). During the treatment process, the incidence of adverse reactions in the study group (2 cases, 4.08%) was lower than that in the control group (9 cases, 18.37%), with a statistically significant difference (p = .025).

CONCLUSION

Febuxostat combined with a low-purine diet can reduce inflammatory factors and alleviate the degree of pain in gout patients, significantly improving their clinical symptoms.

Creating machine learning models that interpretably link systemic inflammatory index, sex steroid hormones, and dietary antioxidants to identify gout using the SHAP (SHapley Additive exPlanations) method

Background

The relationship between systemic inflammatory index (SII), sex steroid hormones, dietary antioxidants (DA), and gout has not been determined. We aim to develop a reliable and interpretable machine learning (ML) model that links SII, sex steroid hormones, and DA to gout identification.

Methods

The dataset we used to study the relationship between SII, sex steroid hormones, DA, and gout was from the National Health and Nutrition Examination Survey (NHANES). Six ML models were developed to identify gout by SII, sex steroid hormones, and DA. The seven performance discriminative features of each model were summarized, and the eXtreme Gradient Boosting (XGBoost) model with the best overall performance was selected to identify gout. We used the SHapley Additive exPlanation (SHAP) method to explain the XGBoost model and its decision-making process.

Results

An initial survey of 20,146 participants resulted in 8,550 being included in the study. Selecting the best performing XGBoost model associated with SII, sex steroid hormones, and DA to identify gout (male: AUC: 0.795, 95% CI: 0.746- 0.843, accuracy: 98.7%; female: AUC: 0.822, 95% CI: 0.754- 0.883, accuracy: 99.2%). In the male group, The SHAP values showed that the lower feature values of lutein + zeaxanthin (LZ), vitamin C (VitC), lycopene, zinc, total testosterone (TT), vitamin E (VitE), and vitamin A (VitA), the greater the positive effect on the model output. In the female group, SHAP values showed that lower feature values of E2, zinc, lycopene, LZ, TT, and selenium had a greater positive effect on model output.

Conclusion

The interpretable XGBoost model demonstrated accuracy, efficiency, and robustness in identifying associations between SII, sex steroid hormones, DA, and gout in participants. Decreased TT in males and decreased E2 in females may be associated with gout, and increased DA intake and decreased SII may reduce the potential risk of gout.

The association between Helicobacter pylori infection and the risk for gout in hyperuricemia patients in China - A cross-sectional study

PURPOSE

Helicobacter pylori (H. pylori) infection has been reported to be associated with multiple metabolic diseases. However, the connection between H. pylori infection and gout has not been explored previously. Our study aimed to investigate the association of gout and H. pylori infection in hyperuricemia population in China.

PATIENTS AND METHODS

This cross-sectional study was performed among the subjects who underwent health checkup in our health promotion center from January 1, 2020 to December 31, 2021. A total of 53,629 subjects with a mean age of 44.2 years were included in this study. H. pylori infection was defined as a positive [13]C-urea breath test. The effect of H. pylori infection on gout was assessed by multiple logistic regression analysis.

RESULTS

720 subjects with gout and 15,077 subjects with asymptomatic hyperuricemia (> 420 µmol/L in male and > 360 µmol/L in female) were enrolled. The prevalence rates of H. pylori infection, hyperuricemia and gout were 26.3%, 29.5%, 1.3%, respectively. The prevalence rate of H. pylori infection was significantly higher in subjects with gout than in those with asymptomatic hyperuricemia (35.0% vs. 27.2%; P<0.001). Multiple logistic regression analysis showed that H. pylori infection was associated with an increased risk of gout independent of serum uric acid level in hyperuricemia population (odds ratio [OR]: 1.320, 95% confidence interval [CI]: 1.124-1.550, P = 0.001).

CONCLUSION

H. pylori infection is positively associated with higher risk of gout in hyperuricemia population. The causal relationship and potential mechanism between H. pylori infection and gout warrants further investigation.

Antigout effects and mechanisms of total flavonoids from prunus tomentosa

BACKGROUND

In recent years, hyperuricemia and acute gouty arthritis have become increasingly common, posing a serious threat to public health. Current treatments primarily involve Western medicines with associated toxic side effects.

OBJECTIVE

This study aims to investigate the therapeutic effects of total flavones from Prunus tomentosa (PTTF) on a rat model of gout and explore the mechanism of PTTF's anti-gout action through the TLR4/NF-κB signaling pathway.

METHODS

We measured serum uric acid (UA), creatinine (Cr), blood urea nitrogen (BUN), tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) levels using an enzyme-linked immunosorbent assay (ELISA). Histopathological changes were observed using HE staining, and the expression levels of relevant proteins were detected through Western blotting.

RESULTS

After PTTF treatment, all indicators improved significantly. PTTF reduced blood levels of UA, Cr, BUN, IL-1β, IL-6, and TNF-α, and decreased ankle swelling.

CONCLUSIONS

PTTF may have a therapeutic effect on animal models of hyperuricemia and acute gouty arthritis by reducing serum UA levels, improving ankle swelling, and inhibiting inflammation. The primary mechanism involves the regulation of the TLR4/NF-κB signaling pathway to alleviate inflammation. Further research is needed to explore deeper mechanisms.

Correlation analysis of serum TLR4 protein levels and TLR4 gene polymorphisms in gouty arthritis patients

OBJECTIVE

The Toll-like receptor (TLR) 4-mediated nuclear factor kappa B (NF-κB) signaling pathway regulates the production of inflammatory factors and plays a key role in the pathogenesis of gouty arthritis. The aim of the present study was to investigate the link among TLR4 gene polymorphisms at various loci, protein expression, and gouty arthritis susceptibility.

METHODS

Between 2016 and 2021, a case-control study was used to collect a total of 1207 study subjects, including 317 male patients with gouty arthritis (gout group) and 890 healthy males (control group). The association between gout susceptibility and different genetic models was analyzed by typing three loci of the TLR4 gene (rs2149356, rs2737191, and rs10759932) using a multiplex point mutation rapid assay, and the association between protein expression and gout was confirmed by measuring TLR4 protein concentrations using enzyme-linked immunosorbent assays (ELISAs).

RESULTS

In a codominant models AA and AG, the rs2737191 polymorphism in the gout group increased the risk of gout compared to the AA genotype (OR = 2.249, 95%CI 1.010~5.008), and the risk of gout was higher for those carrying the G allele compared to the A allele (OR = 2.227, 95%CI 1.006~4.932). TLR4 protein expression was different between the two groups with different locus genotypes. The differences in TLR4 protein expression between the gout group and control group were statistically significant between the following genotypes: the GG and GT genotypes of the rs2149356 polymorphism; the AA and AG genotypes of the rs2737191 polymorphism; and the TT and TC genotypes of the rs10759932 polymorphism(P<0.05). The TLR4 protein level in the gout group (19.19±3.09 ng/ml) was significantly higher than that in the control group (15.85±4.75 ng/ml).

CONCLUSION

The AG genotype of the TLR4 gene rs2737191 polymorphism may be correlated with the development of gouty arthritis. The level of TLR4 protein expression is significantly higher in patients with gouty arthritis than in controls, and there is a correlation between high TLR4 protein expression and the development of gouty arthritis.

Anti-inflammatory and uric acid lowering effects of Euodiae fructus on hyperuricemia and gout mice

The metabolic disease hyperuricemia (HUA) is caused by presence of excessive serum uric acid (UA), which leads to an increased risk of chronic kidney disease and gout. As a widely used traditional Chinese medicine, Euodiae fructus (ER) has strong anti-inflammatory and analgesic effects, however, its therapeutic effects on HUA and gout have not been investigated. To investigate the potential effects and underlying mechanisms, the effect of ER on proinflammatory cytokines and NLRP3 inflammasome activation was studied in mouse bone marrow macrophages. Moreover, a mouse model of HUA and gouty arthritis was established by coadministration of potassium oxonate (PO) and monosodium urate crystals to mice fed a high-fat diet (HFD) for 37 consecutive days. Oral administration of ER aqueous extract was given 1 hour later after the injection of PO for 10 days. Our study showed that ER is a powerful NLRP3 inhibitor in mouse macrophages. Most importantly, ER (0.75 g/kg) treatment substantially decreased the ankle joint thickness ratio, serum UA, creatinine and blood urea nitrogen levels (p < 0.05). Additionally, ER (0.75 g/kg) dramatically reversed the increases in renal urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) as well as the decreases in organic anion transporter 1 (OAT1) and ATP binding cassette subfamily G member 2 (ABCG2) levels (p < 0.05). Moreover, ER (0.75 g/kg) markedly ameliorated the production of the serum inflammatory cytokines IL-1β and TNF-α (p < 0.01), and improved the activation of NLRP3 inflammasome signaling in the kidneys. Taken together, these data indicate that ER, a powerful and specific NLRP3 inhibitor, has multiple anti-HUA, anti-gout and anti-inflammatory effects. Our investigation is designed to experimentally support the conventional use of ER-containing classical herbal formulas in the treatment of HUA-related disorders and may add a new dimension to the clinical application of ER.

The Clinical Significance of Serum Interleukin-36α Levels in Patients with Gout

BACKGROUND

Gout is a chronic inflammatory diseases caused by monosodium urate crystal deposition. However, the role of interleukin (IL)-36 in gout has not dbeen elucidated.

METHODS

We enrolled 75 subjects, including 20 healthy controls (HC), 30 patients with acute gout attack and 25 patients in remission. Baseline data were obtained through clinical interrogation and laboratory data were obtained through tests of blood samples. Serum levels of IL-36α were detected using enzyme-linked immunosorbent assay. Spearman correlation analysis was used to investigate the correlation of IL-36α with other parameters. The diagnostic value of IL-36α was demonstrated using a receiver operating characteristic curve.

RESULTS

The serum IL-36α level of gout patients in acute attack and remission stage was significantly higher than that of HC. Serum IL-36α was positively correlated with alanine transaminase (ALT) and aspartate transaminase (AST). Serum amyloid A (SAA) levels positively correlated with C-reactive protein levels and erythrocyte sedimentation rates. Glutamyl transpeptidase levels positively correlated with AST and ALT levels.

CONCLUSION

In conclusion, serum IL-36α levels were elevated in patients with gout and correlated with the clinical markers of inflammation. Our findings suggest that IL-36α may be a novel inflammatory indicator for gout.

Effects of Low Temperature-Ultrasound-Papain (LTUP) Combined Treatments on Purine Removal from Pork Loin and Its Influence on Meat Quality and Nutritional Value

A combined pretreatment method of "low temperature-ultrasound-papain" (LTUP) was proposed to remove the purine of pork loins. Compared with untreated pork loin, under optimal conditions (temperature 58 °C, ultrasound density 100 W/cm2, and papain concentration 0.085%), the purine removal rate of treated pork loin could reach 59.29 ± 1.39%. The meat quality of pork loin treated with the LTUP method such as hardness and chewiness decreased by 58.37% and 64.38%, respectively, and the in vitro protein digestibility was increased by 19.64%; the cooking loss was decreased by 15.45%, compared with the simulated household blanching process (HT). In view of the high purine removal rate, the losses of free amino acids and soluble peptides were acceptable and reasonable. SEM and LF-NMR results showed that low temperature and ultrasound combined with papain treatment opened a channel for purine transfer and promoted purine dissolution by affecting the protein structure of pork loin. In addition, the migration of water within the muscle tissue was also related to purine removal. In summary, LTUP is recommended as an efficient and green way for the meat industry to remove purine.

Identification of potential biomarkers of gout through weighted gene correlation network analysis

Background

Although hyperuricemia is not always associated with acute gouty arthritis, uric acid is a significant risk factor for gout. Therefore, we investigated the specific mechanism of uric acid activity.

Methods

Using the gout-associated transcriptome dataset GSE160170, we conducted differential expression analysis to identify differentially expressed genes (DEGs). Moreover, we discovered highly linked gene modules using weighted gene coexpression network analysis (WGCNA) and evaluated their intersection. Subsequently, we screened for relevant biomarkers using the cytoHubba and Mcode algorithms in the STRING database, investigated their connection to immune cells and constructed a competitive endogenous RNA (ceRNA) network to identify upstream miRNAs and lncRNAs. We also collected PBMCs from acute gouty arthritis patients and healthy individuals and constructed a THP-1 cell gout inflammatory model, RT-qPCR and western blotting (WB) were used to detect the expression of C-X-C motif ligand 8 (CXCL8), C-X-C motif ligand 2 (CXCL2), and C-X-C motif ligand 1 (CXCL1). Finally, we predicted relevant drug targets through hub genes, hoping to find better treatments.

Results

According to differential expression analysis, there were 76 upregulated and 28 downregulated mRNAs in GSE160170. Additionally, WGCNA showed that the turquoise module was most strongly correlated with primary gout; 86 hub genes were eventually obtained upon intersection. IL1β, IL6, CXCL8, CXCL1, and CXCL2 are the principal hub genes of the protein-protein interaction (PPI) network. Using RT-qPCR and WB, we found that there were significant differences in the expression levels of CXCL8, CXCL1, and CXCL2 between the gouty group and the healthy group, and we also predicted 10 chemicals related to these proteins.

Conclusion

In this study, we screened and validated essential genes using a variety of bioinformatics tools to generate novel ideas for the diagnosis and treatment of gout.

ZnO Nanocages Decorated with Au@AgAu Yolk-Shell Nanomaterials for SERS-Based Detection of Hyperuricemia

Surface-enhanced Raman scattering (SERS) is widely recognized as a highly sensitive technology for chemical detection and biological sensing. In SERS-based biomedical applications, developing highly efficient sensing platforms based on SERS plays a pivotal role in monitoring disease biomarker levels and facilitating the early detection of cancer biomarkers. Hyperuricemia, characterized by abnormally high concentrations of uric acid (UA) in the blood, was associated with a range of diseases, such as gouty arthritis, heart disease, and acute kidney injury. Recent reports have demonstrated the correlation between UA concentrations in blood and tears. In this work, we report the fabrication of SERS substrates utilizing ZnO nanocages and yolk-shell-structured plasmonic nanomaterials for the noninvasive detection of UA in tears. This innovative SERS substrate enables noninvasive and sensitive detection of UA to prevent hyperuricemia-related diseases.

Assessment of the efficacy of alkaline water in conjunction with conventional medication for the treatment of chronic gouty arthritis: A randomized controlled study

BACKGROUND

Chronic gouty arthritis, a prevalent metabolic disorder, has prompted interest in the role of diet and lifestyle in its management. This study examines alkaline water as a non-pharmacological adjunct to traditional medicine, hypothesizing its positive effects on uric acid levels and gout symptoms.

METHODS

In this research, 400 chronic arthritis patients from Guangdong Hydropower Hospital (September 2021-September 2023) were randomly assigned to groups receiving varying concentrations of alkaline water alongside conventional Western medicine, or Western medicine alone. A 1-year follow-up involved assessments using visual analogue scales, joint swelling scores, functional assessment scales, and biochemical markers (serum uric acid, creatinine, urea nitrogen) for comprehensive evaluation.

RESULTS

Pain relief: High-concentration alkaline water significantly reduced VAS pain scores posttreatment (P < .05). Joint swelling: Greatest improvement observed in high-concentration group (P < .001). Daily activity capability: Notable enhancements in daily activity scores in experimental groups (P < .05). Range of joint motion: All groups showed significant improvement posttreatment (P < .05). Inflammatory markers: Experimental groups experienced a notable decrease in C-reactive protein, especially in the low concentration group (P < .001). Erythrocyte sedimentation rate decreases were marginal and not statistically significant (P > .05). Interleukin-1β and tumor necrosis factor-α levels significantly decreased, particularly in the low concentration group. Serum uric acid levels: Significant reduction in serum uric acid observed in all alkaline water groups (P < .05), contrasting with the control group.

CONCLUSION

Alkaline water, particularly at high concentrations, effectively alleviated pain, reduced joint swelling, enhanced daily activities, and improved joint motion in chronic gouty arthritis treatment. It significantly reduced key inflammatory markers (C-reactive protein, interleukin-1β, tumor necrosis factor-α) and serum uric acid levels, suggesting its potential as a valuable adjunct in gout management. The limited impact on erythrocyte sedimentation rate warrants further investigation.

Association Between Hyperuricemia and Ultrasound-Detected Hand Synovitis

OBJECTIVE

Although hand synovitis is prevalent in the older population, the etiology remains unclear. Hyperuricemia, a modifiable metabolic disorder, may serve as an underlying mechanism of hand synovitis, but little is known about their relationship. We assessed the association between hyperuricemia and hand synovitis in a large population-based sample.

METHODS

We performed a cross-sectional study in Longshan County, Hunan Province, China. Hyperuricemia was defined as a serum urate level >420 μmol/L in men and >360 μmol/L in women. Ultrasound examinations were performed on both hands of 4,080 participants, and both gray-scale synovitis and the Power Doppler signal (PDS) were assessed using semiquantitative scores (grades 0-3). We evaluated the association of hyperuricemia with hand gray-scale synovitis (grade ≥2) and PDS (grade ≥1), respectively, adjusting for age, sex, and body mass index.

RESULTS

All required assessments for analysis were available for 3,286 participants. The prevalence of hand gray-scale synovitis was higher among participants with hyperuricemia (30.0%) than those with normouricemia (23.3%), with an adjusted odds ratio (aOR) of 1.28 (95% confidence interval [CI] 1.00-1.62). Participants with hyperuricemia also had a higher prevalence of PDS (aOR 2.36; 95% CI 1.15-4.81). Furthermore, hyperuricemia positively associated, both at the hand and joint levels, with the presence of gray-scale synovitis (aOR 1.27; 95% CI 1.00-1.60 and adjusted prevalence ratio [aPR] 1.26; 95% CI 1.10-1.44, respectively) and PDS (aOR 2.35; 95% CI 1.15-4.79 and aPR 2.34; 95% CI 1.28-4.30, respectively).

CONCLUSION

This population-based study provides more evidence for a positive association between hyperuricemia and prevalent hand synovitis.

Association Between Family History in Patients with Primary Gout and Left Ventricular Diastolic Function: A Cross-Sectional Study

Objective

This study aimed to employ echocardiography for measuring the markers of left ventricular (LV) diastolic function to investigate the effects of family history of gout on the LV diastolic function in patients with primary gout.

Methods

Two hundred and eighty-four patients with primary gout who visited the Department of Rheumatology and Immunology of the First Affiliated Hospital of Chengdu Medical College from September 2020 to July 2022 were selected and their family history of gout, general information, and laboratory markers were recorded. Parameters of LV diastolic function were measured via echocardiography. The correlation between family history and LV diastolic function markers was analyzed using univariate and multivariate regression and the receiver operating characteristic (ROC) curve analyses.

Results

LV diastolic function parameters, peak early mitral diastolic velocity (E)/peak late mitral diastolic velocity (A), and early septal mitral annulus diastolic motion velocity (Sepe'), early lateral mitral annulus diastolic motion velocity (Late') and their mean (e'), were significantly lower in patients with familial primary gout, while left atrial volume index (LAVI) and E/e' were markedly elevated in patients with sporadic primary gout. In patients with family history, the proportion of grade ≥2 LV diastolic insufficiency was distinctly higher than that in patients without family history (41.6% vs 12.3%). Even after adjusting for confounding variables, LAVI, E/A, Sepe', Late', e', E/e' were obviously associated with family history of gout. The area under ROC of family history combined with SUA level for identifying grade ≥2 LV diastolic insufficiency in patients with primary gout was 0.872 (P<0.05).

Conclusion

Family history of gout was closely related to echocardiographic LV diastolic function parameters in patients with gout, what is more, family history of gout combined with SUA level was found to be a valuable indicator for discriminating grade ≥2 LV diastolic insufficiency in patients with primary gout.

Renal interstitial fibrotic assessment using non-Gaussian diffusion kurtosis imaging in a rat model of hyperuricemia

BACKGROUND

To investigate the feasibility of Diffusion Kurtosis Imaging (DKI) in assessing renal interstitial fibrosis induced by hyperuricemia.

METHODS

A hyperuricemia rat model was established, and the rats were randomly split into the hyperuricemia (HUA), allopurinol (AP), and AP + empagliflozin (AP + EM) groups (n = 19 per group). Also, the normal rats were selected as controls (CON, n = 19). DKI was performed before treatment (baseline) and on days 1, 3, 5, 7, and 9 days after treatment. The DKI indicators, including mean kurtosis (MK), fractional anisotropy (FA), and mean diffusivity (MD) of the cortex (CO), outer stripe of the outer medulla (OS), and inner stripe of the outer medulla (IS) were acquired. Additionally, hematoxylin and eosin (H&E) staining, Masson trichrome staining, and nuclear factor kappa B (NF-κB) immunostaining were used to reveal renal histopathological changes at baseline, 1, 5, and 9 days after treatment.

RESULTS

The HUA, AP, and AP + EM group MKOS and MKIS values gradually increased during this study. The HUA group exhibited the highest MK value in outer medulla. Except for the CON group, all the groups showed a decreasing trend in the FA and MD values of outer medulla. The HUA group exhibited the lowest FA and MD values. The MKOS and MKIS values were positively correlated with Masson's trichrome staining results (r = 0.687, P < 0.001 and r = 0.604, P = 0.001, respectively). The MDOS and FAIS were negatively correlated with Masson's trichrome staining (r = -626, P < 0.0014 and r = -0.468, P = 0.01, respectively).

CONCLUSION

DKI may be a non-invasive method for monitoring renal interstitial fibrosis induced by hyperuricemia.

Exploring the anti-gout potential of sunflower receptacles alkaloids: A computational and pharmacological analysis

Gout, a painful condition marked by elevated uric acid levels often linked to the diet's high purine and alcohol content, finds a potential treatment target in xanthine oxidase (XO), a crucial enzyme for uric acid production. This study explores the therapeutic properties of alkaloids extracted from sunflower (Helianthus annuus L.) receptacles against gout. By leveraging computational chemistry and introducing a novel R-based clustering algorithm, "TriDimensional Hierarchical Fingerprint Clustering with Tanimoto Representative Selection (3DHFC-TRS)," we assessed 231 alkaloid molecules from sunflower receptacles. Our clustering analysis pinpointed six alkaloids with significant gout-targeting potential, particularly emphasizing the fifth cluster's XO inhibition capabilities. Through molecular docking and the BatchDTA prediction model, we identified three top compounds-2-naphthylalanine, medroxalol, and fenspiride-with the highest XO affinity. Further molecular dynamics simulations assessed their enzyme active site interactions and binding free energies, employing MM-PBSA calculations. This investigation not only highlights the discovery of promising compounds within sunflower receptacle alkaloids via LC-MS but also introduces medroxalol as a novel gout treatment candidate, showcasing the synergy of computational techniques and LC-MS in drug discovery.

Clinical characteristics of adolescent-onset gout in Chinese: A hospital-based cross-sectional study

OBJECTIVE

Adolescent-onset gout has a greater impact on the lives and health of patients than adult-onset gout. However, there is a relative lack of clinical information on adolescent-onset gout. Hence, we analyzed a Chinese cohort.

METHODS

We studied clinical features of 9,003 Chinese patients. Gout onset age of 12 - 19 years is defined as adolescent-onset group (AG), 20 - 40 years as early-onset group (EG), and 41 - 64 years as late-onset group (LG). Multivariable regression analysis evaluated factors associated with recurrent flares, serum urate (SU) levels, and underexcretion type in AG.

RESULTS

Compared with EG and LG, the AG had higher SU levels [AG: 9.5 (2.2) mg/dL, EG: 8.6 (2.1) mg/dL, LG: 7.73 (2.0) mg/dL, P < 0.001], higher percentage of positive family history of gout (AG: 41.8 %, EG: 29.6 %, LG: 24.6 %, P < 0.001), underexcretion type (AG: 62.4 %, EG: 62.5 %, LG: 58.8 %, P = 0.04), recurrent flares (AG: 78.1 %, EG: 70.3 %, LG: 68.9 %, P = 0.01). Urate-lowering therapy (ULT) initiated [OR 6.58 (95 % CI 1.35 - 32.00)] and hypercholesterolemia [OR 4.16 (95 % CI 1.28 - 13.53)] were associated with recurrent flares. eGFR was identified to be a significant variable of increasing SU levels [beta -0.24 (95 % CI -0.04 to -0.01)]. Hypertriglyceridemia [OR 0.35 (95 % CI 0.17 - 0.71)] was related to underexcretion type.

CONCLUSION

Adolescent-onset gout patients had clinically distinctive features with higher SU levels, BMI, positive gout family history, underexcretion type and recurrent flares. These specific populations were less likely to achieve ULT target, requiring more clinical attention.

Dissecting the risk factors for hyperuricemia in vegetarians in Taiwan

BACKGROUND

Vegetarian diets have been shown to lower the risks of hyperuricemia and gout. Little is known about the risk factors of hyperuricemia in vegetarians.

METHODS

This community-based retrospective case-control study was conducted to establish prediction models for hyperuricemia. From September 5, 2005, to December 31, 2016, 7331 adult vegetarians were recruited at Taipei Tzu Chi Hospital. Hyperuricemia was defined as a serum uric acid concentration greater than 7 mg/dL.

RESULTS

There were 593 (8.1%) vegetarians with hyperuricemia and 6738 (91.9%) without hyperuricemia. We stepwise built up three models for predicting hyperuricemia in vegetarians. The full model (model 3) has the highest area under the receiver operating characteristic curve (AUROC, 85.52%). Additionally, the AUROC of model 3 is 77.97% and 84.85% in vegetarians with or without prior gout history, respectively. Moreover, male gender, hyperlipidemia, body mass index, and serum albumin are independent risk factors for hyperuricemia in vegetarians. In contrast, estimated glomerular filtration rate and proteinuria are independently associated with lower risks of hyperuricemia in vegetarians.

CONCLUSION

Our study revealed that risk factors for hyperuricemia, which includes clinical characteristics, account for more than 85% of discriminatory performance in Taiwanese vegetarians. This model may be helpful for monitoring and preventing hyperuricemia in the population.

The Effects of Pharmacological Urate-Lowering Therapy on Cardiovascular Disease in Older Adults with Gout

Cardiovascular disease is an important cause of mortality in older patients. In addition to the traditional risk factors for cardiovascular disease, hyperuricemia has been increasingly associated with an elevated risk of cardiovascular disease. Uric acid itself has several unfavorable effects on the cardiovascular system, and hyperuricemia can lead to the development of gout. Gout is the most prevalent inflammatory rheumatic disease. Older patients with gout have an increased risk of cardiovascular morbidity and mortality due to an increased prevalence of traditional risk factors, as well as the inflammatory burden of gout activity. As the prevalence of traditional risk factors and the prevalence of both hyperuricemia and gout are increasing in older adults, cardiovascular risk management in these patients is very important. This risk management consists of, on the one hand, treatment of individual traditional risk factors and, on the other hand, of urate lowering, thereby decreasing inflammatory burden of gout. However, there is insufficient evidence to conclude that urate-lowering therapy reduces the risk of cardiovascular events. Moreover, from a cardiovascular point of view, there is no preference for one urate lowering drug over another in patients with gout, nor is there enough evidence to support a preference in patients with gout with increased cardiovascular risk. Personalized treatment in older patients with gout should be aimed at optimizing serum uric acid levels, as well as targeting traditional cardiovascular risk factors. Further prospective randomized trials are needed to support the hypothesis that urate lowering reduces cardiovascular risk in older patients with gout.

Antihyperuricemic activity and inhibition mechanism of xanthine oxidase inhibitory peptides derived from whey protein by virtual screening

Xanthine oxidase (XO), a rate-limiting enzyme in uric acid production, is the pivotal therapeutic target for gout and hyperuricemia. In this study, 57 peptides from α-lactalbumin and β-lactoglobulin were obtained via virtual enzymatic hydrolysis, and 10 XO inhibitory peptides were virtually screened using molecular docking. Then toxicity, allergenicity, solubility, and isoelectric point of the obtained 10 novel peptides were evaluated by in silico tools. The XO activity of these synthetic peptides was tested using an in vitro assay by high-performance liquid chromatography. Their inhibitory mechanism was further explored by molecular docking. The results showed that 4 peptides GL, PM, AL, and AM exhibited higher inhibitory activity, and their half maximal inhibitory concentration in vitro was 10.20 ± 0.89, 23.82 ± 0.94, 34.49 ± 0.89, and 40.45 ± 0.92 mM, respectively. The peptides fitted well with XO through hydrogen bond, hydrophobic interaction, and van der Waals forces, and amino acid residues Glu802, Leu873, Arg880, and Pro1076 played an important role in this process. Overall, this study indicated 4 novel peptides GL, PM, AL, and AM from whey protein exhibited XO inhibitory activity, and they might be useful and safe XO inhibitors for hyperuricemia prevention and treatment.

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

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

Exploring the causal associations of micronutrients on urate levels and the risk of gout: A Mendelian randomization study

BACKGROUND & AIMS

Growing evidence has indicated a potential association between micronutrient levels, urate levels, and the risk of gout. However, the causal association underlying these associations still remains uncertain. Previous observational studies and randomized controlled trials investigating the association between micronutrients, urate levels, and the risk of gout have been limited in their scope and depth. The aim of this study was to utilize Mendelian randomization (MR) to investigate the causal associations between genetically predicted micronutrient levels, urate levels, and the risk of gout.

METHODS

In this study, we conducted a comprehensive examination of 10 specific micronutrients (vitamin B6, vitamin B12, vitamin C, vitamin D, folate, calcium, iron, copper, zinc, and selenium) as potential exposures. Two-sample MR analyses were performed to explore their causal associations with urate levels and the risk of gout. In these analyses, gout data were collected from the Global Biobank Meta-Analysis Initiative (N = 1,069,839, N cases = 30,549) and urate levels data from CKDGen Consortium (N = 288,649) by utilizing publicly available summary statistics from independent cohorts of European ancestry. We performed inverse-variance weighted MR analyses as main analyses, along with a range of sensitivity analyses, such as MR-Egger, weighted median, simple mode, weighted mode, Steiger filtering, MR-PRESSO, and Radial MR analysis, to ensure the robustness of our findings.

RESULTS

The results of our study indicate that there were negative associations between serum vitamin B12 and urate levels, as well as serum folate and the risk of gout. Specifically, we found a negative association between vitamin B12 levels and urate levels, with a β coefficient of -0.324 (95% CI -0.0581 to -0.0066, P = 0.0137) per one standard deviation (SD) increase. Similarly, a negative association was observed between folate levels and gout risk, with an odds ratio of 0.8044 (95% CI 0.6637 to 0.9750, P = 0.0265) per one SD increase. On the other hand, we identified positive associations between serum calcium levels and both urate levels and the risk of gout. Specifically, there was a positive association between serum calcium levels and urate levels (β coefficient: 0.0994, 95% CI 0.0519 to 0.1468, P = 4.11E-05) per one SD increase. Furthermore, a positive association was found between serum calcium levels and the risk of gout, with an odds ratio of 1.1479 (95% CI 1.0460 to 1.2598, P = 0.0036) per one SD increase. These findings were robust in extensive sensitivity analyses. By employing MR-PRESSO and Radial MR to eliminate outliers, the observed associations have been reinforced. No clear associations were found between the other micronutrients and the urate levels, as well as the risk of gout.

CONCLUSION

Our findings provided evidence that there were negative associations between serum vitamin B12 and urate levels, as well as serum folate and the risk of gout, while positive associations existed between the serum calcium levels and urate levels, as well as the risk of gout.