Molecular basis of oxidative stress in gouty arthropathy

Food-derived bioactive peptides with anti-hyperuricemic activity: A comprehensive review

Hyperuricemia (HU) is a metabolic disorder caused by the overproduction or underexcretion of uric acid (UA) in the human body. Several approved drugs for the treatment of HU are available in the market; however, all these allopathic drugs exhibit multiple side effects. Therefore, the development of safe and effective anti-HU drugs is an urgent need. Natural compounds derived from foods and plants have the potential to decrease UA levels. Recently, food-derived bioactive peptides (FBPs) have gained attention as a functional ingredient owing to their biological activities. In the current review, we aim to explore the urate-lowering potential and the underlying mechanisms of FBPs. We found that FBPs mitigate HU by reducing blood UA levels through inhibiting key enzymes such as xanthine oxidase, increasing renal UA excretion, inhibiting renal UA reabsorption, increasing anti-oxidant activities, regulating inflammatory mediators, and addressing gut microbiota dysbiosis. In conclusion, FBPs exhibit strong potential to ameliorate HU.

Traditional herbal medicine: Therapeutic potential in acute gouty arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Acute gouty arthritis (AGA) is characterized by a rapid inflammatory reaction caused by the build-up of monosodium urate (MSU) crystals in the tissues surrounding the joints. This condition often associated with hyperuricemia (HUA), is distinguished by its symptoms of intense pain, active inflammation, and swelling of the joints. Traditional approaches in AGA management often fall short of desired outcomes in clinical settings. However, recent ethnopharmacological investigations have been focusing on the potential of Traditional Herbal Medicine (THM) in various forms, exploring their therapeutic impact and targets in AGA treatment.

AIM OF THE REVIEW

This review briefly summarizes the current potential pharmacological mechanisms of THMs - including active ingredients, extracts, and prescriptions -in the treatment of AGA, and discusses the relevant potential mechanisms and molecular targets in depth. The objective of this study is to offer extensive information and a reference point for the exploration of targeted AGA treatment using THMs.

MATERIALS AND METHODS

This review obtained scientific publications focused on in vitro and in vivo studies of anti-AGA THMs conducted between 2013 and 2023. The literature was collected from various journals and electronic databases, including PubMed, Elsevier, ScienceDirect, Web of Science, and Google Scholar. The retrieval and analysis of relevant articles were guided by keywords such as "acute gouty arthritis and Chinese herbal medicine," "acute gouty arthritis herbal prescription," "acute gouty arthritis and immune cells," "acute gouty arthritis and inflammation," "acute gouty arthritis and NOD-like receptor thermoprotein domain associated protein 3 (NLRP3)," "acute gouty arthritis and miRNA," and "acute gouty arthritis and oxidative stress."

RESULTS

We found that AGA has a large number of therapeutic targets, highlighting the effectiveness the potential of THMs in AGA treatment through in vitro and in vivo studies. THMs and their active ingredients can mitigate AGA symptoms through a variety of therapeutic targets, such as influencing macrophage polarization, neutrophils, T cells, natural killer (NK) cells, and addressing factors like inflammation, NLRP3 inflammasome, signaling pathways, oxidative stress, and miRNA multi-target interactions. The anti-AGA properties of THMs, including their active components and prescriptions, were systematically summarized and categorized based on their respective therapeutic targets.

CONCLUSION

phenolic, flavonoid, terpenoid and alkaloid compounds in THMs are considered the key ingredients to improve AGA. THMs and their active ingredients achieve enhanced efficacy through interactions with multiple targets, of which NLRP3 is a main therapeutic target. Nonetheless, given the intricate composition of traditional Chinese medicine (TCM), additional research is required to unravel the underlying mechanisms and molecular targets through which THMs alleviate AGA.

Investigating the Involvement of the NLRP3/ASC/Caspase-1 and NF-κB/MAPK Pathways in the Pathogenesis of Gouty Arthritis: Insights from Irradiated and non-irradiated Trifolium alexandrium L. Extracts and Some Metabolites

ETHNOPHARMACOLOGICAL RELEVANCE

Trifolium alexandrinum L. (TA), has traditionally been used in folk medicine for its anti-inflammatory properties against hyperuricemia and gout. However, the specific mechanisms of action of TA have not been thoroughly studied.

AIM OF THE WORK

This study aimed to evaluate the protective effects of irradiated (TR25) and non-irradiated (TR0) Trifolium alexandrinum L. aqueous extract (TAAE), along with two isolated compounds, caffeine (CAF) and saponin (SAP), in a rat model of acute gouty arthritis (GA).

MATERIALS AND METHODS

The GA model was established by injecting a monosodium urate (MSU) suspension into the knee joint. Synovial tissue pathology was assessed, and levels of TNF-α, IL-6, IL-1β, NF-κB, mTOR, AKT1, PI3K, NLRP3, and ASC were measured by ELISA. mRNA expression of ERK1, JNK, and p-38 MAPK was detected using qRT-PCR, and Caspase-1 protein expression was assessed by immunohistochemical analysis. Knee swelling, uric acid levels, liver and kidney function, and oxidative stress markers were also evaluated.

RESULTS

TAAE analysis identified 170 compounds, with 73 successfully identified using LC-HR-MS/MS, including caffeine citrate and theasapogenol B glycoside as the main constituents. The studied materials demonstrated significant protective effects against GA. TR25 administration significantly mitigated knee joint circumference compared to other treatments. It demonstrated potential in alleviating hyperuricemia, renal and hepatic impairments induced by MSU crystals. TR25 also alleviated oxidative stress and reduced levels of IL1β, IL-6, TNF-α, and NF-κB. Weak Caspase-1 immune-positive staining was observed in the TR25 group. TR25 decreased NLRP3 and ASC expression, reducing inflammatory cytokine levels in GA. It effectively inhibited the PI3K, AKT, and mTOR signaling pathways, promoting autophagy. Additionally, TR25 suppressed ERK1, JNK, and p-38 MAPK gene expression in synovial tissue. These effects were attributed to various components in TAAE, such as flavonoids, phenolic acids, tannins, alkaloids, and triterpenes.

CONCLUSION

Importantly, irradiation (25 KGy) enhanced the antioxidant effects and phtchemical contents of TAAE. Additionally, TR0, TR25, CAF, and SAP exhibited promising protective effects against GA, suggesting their therapeutic potential for managing this condition. These effects were likely mediated through modulation of the NLRP3/ASC/Caspase-1 and ERK/JNK/p-38 MAPK signaling pathways, as well as regulation of the PI3K/AKT/mTOR pathway. Further research is warranted to fully elucidate the underlying mechanisms and optimize their clinical applications.

A study on the antioxidant, anti-inflammatory, and xanthine oxidase inhibitory activity of the Artemisia vulgaris L. extract and its fractions

ETHNOPHARMACOLOGICAL RELEVANCE

Vietnamese people use mugwort (Artemisia vulgaris L.) to treat arthritis and gout. Our previous research shows that mugwort contains flavonoids, and its extract possesses antibacterial and anti-inflammatory activities. However, no publications have been on the xanthine oxidase inhibitory activity of mugwort and acute anti-inflammatory activity in vivo.

AIM OF THE STUDY

The study aimed to verify the antioxidant, xanthine oxidase inhibitory, and anti-inflammatory capabilities of mugwort extract in vitro and in vivo, isolate phyto-compounds from potential bioactive fractions, and then evaluate their potential in inhibiting xanthine oxidase.

METHODS

According to established methods, the extract and the active flavonoids were obtained using different chromatographic techniques. DPPH, ABTS, reducing power, and H2O2 elimination were used to evaluate antioxidant activity. The model of LPS-induced RAW264.7 cells was used to measure the inhibition of NO production. The carrageenan-induced paw oedema model was used to assess acute inflammation in mice. In vitro, xanthine oxidase inhibition assay was applied to investigate the effects of extract/compounds on uric acid production. Chemical structures were identified by spectral analysis.

RESULTS

The assessment of the acute inflammatory model in mice revealed that both the 96% ethanol and the 50% ethanol extracts significantly decreased oedema in the mice's feet following carrageenan-induced inflammation. 96% ethanol extract exhibited a better reduction in oedema at the low dose. The analysis revealed that the ethyl acetate fraction had the highest levels of total polyphenols and flavonoids. Additionally, this fraction demonstrated significant antioxidant activity in various assays, such as DPPH, ABTS, reducing power, and H2O2 removal. Furthermore, it displayed the most potent inhibition of xanthine oxidase, an anti-inflammatory activity. Five phytochemicals were isolated and determined from the active fraction such as luteolin (1), rutin (2), apigenin (3), myricetin (4), and quercetin (5). Except for rutin, the other compounds demonstrated the ability to inhibit effective xanthine oxidase compared to standard (allopurinol). Moreover, quercetin (5) inhibited NO production (IC50 21.87 μM).

CONCLUSION

The results indicate that extracts from A. vulgaris effectively suppressed the activity of xanthine oxidase and exhibited antioxidant and anti-inflammatory properties, potentially leading to a reduction in the production of uric acid in the body and eliminating ROS. The study identified mugwort extract and bioactive compounds derived from Artemisia vulgaris, specifically luteolin, apigenin, and quercetin, as promising xanthine oxidase inhibitors. These findings suggest that further development of these compounds is warranted. At the same time, the above results also strengthen the use of mugwort to treat gout disease in Vietnam.

Association between oxidative balance score and risk of gout: The NHANES cross-sectional study, 2007-2018

BACKGROUND

The Oxidative Balance Score (OBS) is a systematic tool to assess the effects of diet and lifestyle in relation to oxidative stress. The association between OBS and gout has not been reported previously. We conducted a cross-sectional study to investigate the complex association between OBS and gout in US adults.

METHODS

In all, 10 492 participants were included in this study. The exposure variable was OBS, which was scored by 16 dietary and four lifestyle factors. Multivariate logistic regression, subgroup analysis, and restricted cubic spline (RCS) regression were used to analyze the association between OBS and gout.

RESULTS

Compared with the lowest OBS quartile group (Q1), the multivariate corrected odds ratio (OR) (95% confidence interval [C]) for the highest quartile of OBS (Q4) was 0.72 (0.52-1.00) (p = .13 for trend); furthermore, the RCS showed a negative linear relationship between OBS and gout (p-nonlinear = .606).

CONCLUSION

In conclusion, the risk of gout is higher with high OBS. The prevalence of gout decreased with higher OBS. Diabetes may alter this negative correlation.

Purine Metabolism and Hexosamine Biosynthetic Pathway Abnormalities in Diarrheal Weaned Piglets Identified Using Metabolomics

Post-weaning diarrhea significantly contributes to the high mortality in pig production, but the metabolic changes in weaned piglets with diarrhea remain unclear. This study aimed to identify the differential metabolites in the urine of diarrheal weaned piglets and those of healthy weaned piglets to reveal the metabolic changes associated with diarrhea in weaned piglets. Nine 25-day-old piglets with diarrhea scores above 16 and an average body weight of 5.41 ± 0.18 kg were selected for the diarrhea group. Corresponding to the body weight and sex of the diarrhea group, nine 25-month-old healthy piglets with similar sex and body weights of 5.49 ± 0.21 kg were selected as the control group. Results showed that the serum C-reactive protein and cortisol of piglets in the diarrhea group were higher than those in the control group (p < 0.05). The mRNA expression of TNF-α, IFN-γ in the jejunum and colon, and IL-1β in the jejunum were increased in diarrhea piglets (p < 0.05), accompanied by a reduction in the mRNA expression of ZO-1, ZO-2, and CLDN1 in the jejunum and colon (p < 0.05); mRNA expression of OCLN in the colon also occurred (p < 0.05). Metabolomic analysis of urine revealed increased levels of inosine, hypoxanthine, guanosine, deoxyinosin, glucosamine, glucosamine-1-p, N-Acetylmannosamine, chitobiose, and uric acid, identified as differential metabolites in diarrhea piglets compared to the controls. In summary, elevated weaning stress and inflammatory disease were associated with the abnormalities of purine metabolism and the hexosamine biosynthetic pathway of weaned piglets. This study additionally indicated the presence of energy metabolism-related diseases in diarrheal weaned piglets.

Associations Between Composite Dietary Antioxidant Index and Gout: National Health and Nutrition Examination Survey 2007-2018

Introduction: To explore the relationship between the composite dietary antioxidant index (CDAI) and gout to provide support for preventing gout through dietary intervention. Methods: Eligible participants from the 2007 to 2018 National Health and Nutrition Examination Survey aged 20 years and older were included in this cross-sectional study. The weighted chi-square test was used to compare the categorical variables difference between CDAI quartiles groups. The weighted univariate and binary logistic regression analysis were used to test the association between variables and gout. The weighted multivariable logistic regression was used to test the association of CDAI and gout in 4 different models. Subgroup analysis on the associations of CDAI with gout was conducted with stratified factors. Results: The final participants were 26,117, 13,103 (50.17%) were female, 8718 (33.38%) were 40-59 years, 11,200 (42.88%) were white and 1232 (4.72%) had gout. After adjusting for all covariates, the CDAI was associated with gout (odds ratio (OR), .97; 95% CI: .95-1.00). Participants in the highest CDAI quantile group were at low risk of gout (odds ratio (OR), .65; 95% CI: .50-.84) versus those in the lowest quantile group. Subgroup analysis and interaction test showed no significant dependence on diabetes mellitus (DM), marital status, alcohol status, hypertension, poverty income ratio (PIR), education level, body mass index (BMI), smoke status, age, sex, race, and chronic kidney disease (CKD) on this association (all p for interaction >.05). Conclusions: Composite dietary antioxidant index was inversely associated with gout in US adults, and dietary antioxidant intervention might be a promising method in the therapy of gout and greater emphasis should be placed on zinc, selenium, carotenoids, vitamins A, C, and E.

Targeted treatment of gouty arthritis by biomineralized metallic nanozyme-mediated oxidative stress-mitigating nanotherapy

Gouty arthritis is characterized by chronic deposition of monosodium urate (MSU) crystals in the joints and other tissues, resulting in the production of excess reactive oxygen species (ROS) and proinflammatory cytokines that intensify synovial inflammation. This condition is mainly associated with inflammatory M1 macrophage activation and oxidative stress production. Hence, gout symptoms can often be resolved by eliminating M1 macrophage activation and scavenging oxidative stress in the inflamed areas. Herein, we developed M1-macrophage-targeting biomineralized metallic nanozymes (FALNZs) that deplete oxidative stress and reduce the M1 macrophage levels to mitigate gouty arthritis. Intra-articular injection of the FALNZs targets inflammatory macrophages and suppresses ROS levels in joints with MSU-crystal-induced arthritis. In addition, the FALNZs alleviate joint swelling, inflammatory cytokine production, and pathological features of the joints. Overall, the proposed therapeutic approach is biocompatible and is an effective ROS scavenger for the treatment of gouty pathogenesis.

Polydatin ameliorates inflammation and oxidative stress associated with MSU-induced gouty arthritis in mice by regulating PPAR-γ and ferritin activation

AIMS

Polygonum cuspidatum Sieb. et Zucc is one of the commonly used herbs for the treatment of gouty arthritis, and polydatin is one of its main effective components. This study evaluated the therapeutic potential of polydatin for the treatment of gout.

MAIN METHODS

The ankle joint of C57BL/6 mice were injected with MSU suspensions to simulate human gouty arthritis, and oral treatment with polydatin (25, 50, and 100 mg/kg body weight) was performed at 1 h after MSU crystal injection. The effect of polydatin on model mice was evaluated by measuring ankle swelling, gait, histopathological analysis, proinflammatory cytokine expression, as well as the contents of NO, MDA and GSH. The targets of polydatin were explored by Real-Time PCR and IHC.

KEY FINDINGS

Treatment with polydatin inhibited ankle swelling, improved abnormal gait, and reduced ankle lesions dose-dependently. Moreover, polydatin decreased pro-inflammatory cytokine expression, and promoted expression of anti-inflammatory cytokine. In addition, polydatin inhibited MSU-induced oxidative stress by decreasing oxidative product (NO, MDA) generation and promote the antioxidant (GSH). Further, we found that polydatin reduced inflammation by decreasing the expression of NLRP3 inflammasome component via activating PPAR-γ. Moreover, polydatin can protect against iron overload and attenuate oxidative stress by promoting the activation of ferritin.

SIGNIFICANCE

Our findings indicates that polydatin ameliorates MSU-induced inflammation and oxidative stress by regulating PPAR-γ and ferritin activation in gouty arthritis model mice, and this research result suggests that polydatin has therapeutic potential for the treatment of gout in humans through multiple targets.

Genetic contributions to female gout and hyperuricaemia using genome-wide association study and polygenic risk score analyses

OBJECTIVES

To identify genetic variants and polygenic risk score (PRS) relating to female gout and asymptomatic hyperuricaemia (AH) in a genome-wide association study (GWAS).

METHODS

Gout, AH and normouricemia controls were included from Taiwan biobank and China Medical University Hospital. All participants were divided into discovery and replication cohorts for GWAS. PRS was estimated according to whether the variant exhibited a protective effect on the phenotypes or not. Each cohort was separated into two groups by the age of 50 years old.

RESULTS

A total of 59 472 females were enrolled, and gout and AH occupied 1.60% and 19.59%, respectively. Six variants located in genes SLC2A9, C5orf22, CNTNAP2 and GLRX5 were significantly predictors of female gout in those aged ≥50. For those aged <50 years old, only the variant rs147750368 (SPANXN1) on chromosome X was found. Most variants located in genes SLC2A9, ZNF518B, PKD2 and ABCG2 were found to be significantly related to AH in both age groups. The PRS could explain ∼0.59% to 0.89% of variance of gout in variants with protective effects, which showed 6.2 times of mean PRS in the risk variants, but only 1.2 times in the AH phenotype. Moreover, the PRS also revealed a dose-response trend between AH rates and quartile scores.

CONCLUSION

The variants in gene SLC2A9 are the major genetic factors for females associated with gout in those aged ≥50. PRS can provide a more robust prediction of the gout/AH under a homogeneous selection of variants that show effects on the traits.

The ABCG2 rs2231142 polymorphism and the risk of nephrolithiasis: A case-control study from the Taiwan biobank

BACKGROUND

Hyperuricemia and gout are risk factors of nephrolithiasis. However, it is unclear whether the ABCG2 gene contributes to the development of nephrolithiasis. We aimed to investigate the interaction between the ABCG2 rs2231142 variant and incident nephrolithiasis in the Taiwanese population.

METHODS

A total of 120,267 adults aged 30-70 years were enrolled from the Taiwan Biobank data-base in this retrospective case-control study and genotyped for rs2231142. The primary outcome was the prevalence of self-reported nephrolithiasis. The odds ratio (OR) of incident nephrolithiasis was analyzed by multivariable logistic regression models with adjustment for multifactorial confounding factors. Associations of the ABCG2 rs2231142 variant with serum uric acid levels, and the incident nephrolithiasis were explored.

RESULTS

The frequency of rs2231142 T allele was 53%, and 8,410 participants had nephrolithiasis. The multivariable-adjusted OR (95% confidence interval) of nephrolithiasis was 1.18 (1.09-1.28) and 1.12 (1.06-1.18) for TT and GT genotypes, respectively, compared with the GG genotype (p<0.001), specifically in the male population with hyperuricemia. Higher age, male sex, hyperlipidemia, hypertension, diabetes mellitus, hyperuricemia, smoking and overweight were independent risk factors for nephrolithiasis. In contrast, regular physical exercise is a protective factor against nephrolithiasis.

CONCLUSIONS

ABCG2 genetic variation is a significant risk of nephrolithiasis, independent of serum uric acid levels. For rs2231142 T allele carriers, our result provides evidence for precision healthcare to tackle hyperuricemia, comorbidities, smoking, and overweight, and recommend regular physical exercise for the prevention of nephrolithiasis.

Naringenin Prevents Inflammation, Apoptosis, and DNA Damage in Potassium Oxonate-Induced Hyperuricemia in Rat Liver Tissue: Roles of Cytochrome C, NF-κB, Caspase-3, and 8-Hydroxydeoxyguanosine

Background: Hyperuricemia (HU) is a metabolic disease characterized by high uric acid levels in the blood. HU is a risk factor for diabetes, cardiovascular complications, metabolic syndrome, and chronic kidney disease. Purpose: The present study was performed to determine the effect of experimental HU on xanthine oxidase (XO), tumor necrosis factor-alpha (TNF-α), nuclear factor-kappa B (NF-κB), interleukin-17 (IL-17), cytochrome C, glutathione peroxidase (GPx), caspase-3, and 8-hydroxydeoxyguanosine (8-OHdG) levels in liver tissues of rats. Study Design: Thirty-five, male, Wistar albino-type rats were used for this study. Experimental groups were formed as follows: Group 1: control group; Group 2: potassium oxonate (PO) group; group 3: PO+NAR (naringenin; 2 weeks) group; and Group 4: PO (2 weeks)+NAR (2 weeks) group (total of 4 weeks). Methods: The first group was not given anything other than normal rat food and drinking water. In the second group, a 250 mg/kg intraperitoneal dose of PO was administered for 2 weeks. In the third group, 250 mg/kg intraperitoneal PO (application for 2 weeks) and 100 mg/kg NAR intraperitoneally 1 hr after each application were administered. In the fourth group, intraperitoneal PO administration was applied for 2 weeks, followed by intraperitoneal administration of NAR for 2 weeks (4 weeks in total). At the end of the experimental period, XO, TNF-α, NF-κB, IL-17, cytochrome C, GPx, caspase-3, and 8-OHdG levels were determined in liver tissues. Results: HU increased XO, TNF-α, NF-κB, IL-17, cytochrome C, caspase-3, and 8-OHdG levels in liver tissues. However, both 2 and 4 weeks of NAR supplementation decreased these values, and also NAR supplementation led to an increase in GPx levels in tissues. Conclusions: The results of the study show that increased inflammation, apoptosis, and DNA damage in experimental HU can be prevented by administration of NAR due to inhibition of cytochrome C, NF-κB, caspase-3, and 8-OHdG.

Early hearing loss detection in gout using extended high frequency audiometry

OBJECTIVE

The study aimed to analyse the hearing levels of patients with gout using extended high frequencies (EHFs) audiometry. Thus, we aimed to reveal the early detectability of potential hearing losses.

DESIGN

Comparative cross-sectional study.

SETTINGS

A single centre patient was diagnosed with gout disease.

PARTICIPANTS

Two groups consisted of 32 patients with gout and 32 healthy volunteers.

MAIN OUTCOME MEASURES

The primary outcome was hearing thresholds in pure tone (PT) audiometry and EHFs audiometry. Also, the association between audiometric results and haematological and biochemical parameters were evaluated.

RESULTS

There was no significant difference between groups in terms of mean hearing thresholds in PT audiometry. But, at all frequencies above 4000 Hz (4000-18 000 Hz), the hearing thresholds were significantly higher in patients with gout. Also, the hearing thresholds above 8000 Hz were positively correlated with serum uric acid levels. Hearing thresholds at higher frequencies were positively correlated with haemoglobin levels and negatively correlated with high-density lipoprotein levels.

CONCLUSION

To our knowledge, this is the first study in the literature demonstrating the high frequency of hearing loss in patients with gout using EHFs audiometry. We consider that using EHFs audiometry should have an important place in the early detection of potential hearing losses in gout patients.

Anti-inflammatory and Antioxidant Effect of Poly-gallic Acid (PGAL) in an In Vitro Model of Synovitis Induced by Monosodium Urate Crystals

Gout is a chronic and degenerative disease that affects the joints and soft tissues because of the crystalline deposit of monosodium urate. The interaction between monosodium urate crystals (MSU) and synoviocytes generates oxidative and inflammatory states. These physiological characteristics have promoted the study of poly-gallic acid (PGAL), a poly-oxidized form of gallic acid reported to be effective in in vitro models of inflammation. The effect of PGAL in an in vitro model of oxidation and synovial inflammation induced by MSU was evaluated after 24 h of stimulation through the morphological changes, the determination of oxidative stress (OS), IL-1β, and the phagocytosis of the MSU. A 20% reduction in synovial viability and the generation of vesicles were observed when they were exposed to MSU. When PGAL was used at 100 and 200 µg/ml, cell death was reduced by 30% and 17%, respectively. PGAL both doses reduce the vesicles generated by MSU. OS generation in synoviocytes exposed to 100 µg/ml and 200 µg/ml PGAL decreased by 1.28 and 1.46 arbitrary fluorescence units (AFU), respectively, compared to the OS in synoviocytes exposed to MSU (1.9 AFU). PGAL at 200 µg/ml inhibited IL-1β by 100%, while PGAL at 100 µg/ml inhibited IL-1β by 66%. The intracellular MSU decreased in synoviocytes stimulated with 100 µg/ml PGAL. The PGAL has a cytoprotective effect against damage caused by MSU in synoviocytes and can counteract the oxidative and inflammatory response induced by the crystals probably because it exerts actions at the membrane level that prevent phagocytosis of the crystals.

A review on benefits of quercetin in hyperuricemia and gouty arthritis

Hyperuricemia becomes a public health problem worldwide. It is not only a major risk factor for gout but also associated with the development of life-threatening diseases such as chronic kidney disease and cardiovascular diseases. Although there are several available therapeutic drugs, some serious adverse effects and contraindications are concerned. These drive the search for an alternative therapy that is effective and safe. Quercetin is of particular interesting since it has been reported numerous pharmacological activities, especially anti-hyperuricemia, antioxidant, anti-inflammation and amelioration of metabolic syndromes and cardiovascular diseases which are comorbidities of hyperuricemia and gout. In addition, quercetin has been widely used as a health supplement for many diseases however, the use for hyperuricemia and gout has not been indicated. Therefore, this review aims to gather and summarize published data regarding the efficacy in preclinical and clinical studies along with possible mechanism of action, and safety aspect of quercetin in order to support the use of quercetin as a dietary supplement for prevention and management of hyperuricemia and gouty arthritis and/or use as alternative or combination therapy to minimize the side effects of the conventional drugs.

The Relationship Between Ambient Air Pollution and Hospitalizations for Gout in a Humid Subtropical Region of China

Objective

Gout is a chronic disease caused by the deposition of sodium urate (MSU) crystals. Available data on the association between environmental hazards and gout are scarce. The present study was present to investigate the relationship between short-term exposure to air pollution and hospitalizations for acute gout from 2016 to 2020 in Anqing City, China.

Methods

Daily records of hospital admissions for acute gout in Anqing from 1 January 2016 to 31 December 2020 were retrieved from the tertiary first-class hospitals in Anqing. Air pollutants and meteorological data were obtained from the China Environmental Monitoring Station and China Meteorological Data Service Center respectively. We used a time-series analysis to explore the association between air pollution (NO₂, O₃, and CO) and hospitalizations for acute gout, and conducted stratified analyses by gender, age and season.

Results

We observed an association between NO₂ and hospitalizations for gout (lag 0, relative risk (RR):1.022, 95% confidence interval (CI):1.004-1.041). For every 1 mg/m³ increase in CO concentration, hospitalizations for gout increased by 3.9% (lag 11 days, RR=1.039, 95% CI: 1.004-1.076). Intriguingly, there was a negative association between O₃ and hospitalizations for gout (lag0, RR=0.986, 95% CI: 0.976-0.996). Stratified analyses showed that exposure to high levels of NO₂ was considered to be more vulnerable to gout in cold season.

Conclusion

Our study showed that short-term exposure to NO₂ and CO has a significant effect on hospitalizations for acute gout.

miR-3146 induces neutrophil extracellular traps to aggravate gout flare

Background

Gout is an inflammatory arthritis and is characterized by the accumulation of deposited monosodium urate (MSU) crystals in the joints. miRNAs may act as key regulators of gout pathogenesis. The aim of our study was to explore the underlying role and molecular mechanism of miR‐3146 in the formation of neutrophil extracellular traps (NETs) during the pathogenesis of gout.

Methods

The expression of miR‐3146 and sirtuin 1 (SIRT1) was determined by real‐time reverse transcription‐polymerase chain reaction and Western blot, respectively. The luciferase reporter assay was performed to identify the targeting relationship between miR‐3146 and SIRT1. Reactive oxygen species (ROS) production was detected by fluorescent staining. NETs formation was demonstrated via immunofluorescence staining and ELISA method. Gout model was induced in rats to verify the effects of miR‐3146 inhibition on histopathological changes and NETs.

Results

Here, we found miR‐3146 expression was dramatically increased in neutrophils of patients with gout, which was accompanied with the higher levels of NETs. MSU crystals significantly increased miR‐3146 expression and ROS production in neutrophils. The NETs process was also triggered by MSU crystals. Furthermore, we verified the interaction between miR‐3146 and SIRT1. Additionally, antagomir‐3146‐based therapy effectively inhibited the formation of NETs in rats with gout.

Conclusion

Our findings indicated that miR‐3146‐mediated NETs formation may play a potential role in the pathogenesis of gout. These results suggested that miR‐3146 could be used as a potential therapeutic target for the treatment of gout.

Musculoskeletal ultrasound features-based scoring system can evaluate the severity of gout and asymptomatic hyperuricaemia

Objectives:

To develop a tool which can evaluate the severity of the joint injury in individuals with gout and asymptomatic hyperuricaemia.

Methods:

This retrospective study included 616 male patients: 245 with asymptomatic hyperuricaemia and 371 with intercritical gout. All patients underwent ultrasonography of the knee, ankle and first metatarsophalangeal (MTP) joints. Ultrasound features that were significantly different between groups were entered into a binary logistic regression analysis to identify discriminative factors. The ultrasound signs were scored based on their odds ratios, which were then used to evaluate the severity of gout and asymptomatic hyperuricaemia. The performance of the ultrasound score was validated in an additional population including 163 patients with asymptomatic hyperuricaemia and 196 patients with gout.

Results:

Ultrasound signs were scored as follows: knee joint: synovial effusion, 2 points, tophus, 5 points; ankle joint: synovial effusion, 2 points, synovial hypertrophy, 5 points, tophus, 3 points, bone erosion, 7 points; and first MTP joint: double contour sign, 2 points, synovial hypertrophy, 3 points, tophus, 9 points, bone erosion, 4 points. The maximum possible total score was 42. The optimal cut-off score for gout was 6.5. The sensitivity, specificity and area under the receiver operating characteristic curve (AUC) were 86.9%, 75.2% and 0.878, respectively. The patients were stratified according to their ultrasound score (range 0–42). The prevalence of intercritical gout, tophi, and bone erosion increased with the increase of the score. In the validation population, 83.20% of 193 patients with gout had ultrasound scores above 6.5; 76.10% of 163 patients with asymptomatic hyperuricaemia had ultrasound scores under 6.5.

Conclusion:

The scoring system based on the differential ultrasound signs can effectively evaluate the severity of joint injury in individuals with gout and asymptomatic hyperuricaemia.

β-Caryophyllene Ameliorates MSU-Induced Gouty Arthritis and Inflammation Through Inhibiting NLRP3 and NF-κB Signal Pathway: In Silico and In Vivo

Gouty arthritis serves as an acute reaction initiated by the deposition of monosodium urate (MSU) crystals around the joints. In this study, the anti-inflammatory effects of phytochemical β-caryophyllene on MSU crystal-induced acute gouty arthritis in vivo and in silico were explored. Through bioinformatics methods and molecular docking, it screened the specific influence pathway of β-caryophyllene on gout. Certain methods including enzyme-linked immunosorbent assay, western blotting, and immunohistochemical staining were adopted to quantify. β-caryophyllene significantly reduced inflammation and function of ankle joints in MSU Crystals-induced gouty arthritis rats, while decreasing serum cytokine levels. Furthermore, it inhibited the expressions of NLRP3, Caspase-1, ASC, TLR4, MyD88, p65, and IL-1β in the synovial tissue so as to reduce inflammation and protect ankle joints’ function. A new research approach in which β-caryophyllene treatment to acute attacks of gout is provided through the research results.

The Role of Oxidative Stress in Hyperuricemia and Xanthine Oxidoreductase (XOR) Inhibitors

Uric acid is the end product of purine metabolism in humans. Hyperuricemia is a metabolic disease caused by the increased formation or reduced excretion of serum uric acid (SUA). Alterations in SUA homeostasis have been linked to a number of diseases, and hyperuricemia is the major etiologic factor of gout and has been correlated with metabolic syndrome, cardiovascular disease, diabetes, hypertension, and renal disease. Oxidative stress is usually defined as an imbalance between free radicals and antioxidants in our body and is considered to be one of the main causes of cell damage and the development of disease. Studies have demonstrated that hyperuricemia is closely related to the generation of reactive oxygen species (ROS). In the human body, xanthine oxidoreductase (XOR) catalyzes the oxidative hydroxylation of hypoxanthine to xanthine to uric acid, with the accompanying production of ROS. Therefore, XOR is considered a drug target for the treatment of hyperuricemia and gout. In this review, we discuss the mechanisms of uric acid transport and the development of hyperuricemia, emphasizing the role of oxidative stress in the occurrence and development of hyperuricemia. We also summarize recent advances and new discoveries in XOR inhibitors.

The Efficacy and Mechanism of Chinese Herbal Medicines in Lowering Serum Uric Acid Levels: A Systematic Review

Background. Chinese herbal medicines are widely used to lower serum uric acid levels. However, no systemic review summarizes and evaluates their efficacies and the underlying mechanisms of action. Objectives. To evaluate the clinical and experimental evidences for the effectiveness and the potential mechanism of Chinese herbal medicines in lowering serum uric acid levels. Methods. Four electronic databases PubMed, Wed of Science, the Cochrane Library and Embase were used to search for Chinese herbal medicines for their effects in lowering serum uric acid levels, dated from 1 January 2009 to 19 August 2020. For clinical trials, randomized controlled trials (RCTs) were included; and for experimental studies, original articles were included. The methodological quality of RCTs was assessed according to the Cochrane criteria. For clinical trials, a meta-analysis of continuous variables was used to obtain pooled effects. For experimental studies, lists were used to summarize and integrate the mechanisms involved. Results. A total of 10 clinical trials and 184 experimental studies were included. Current data showed that Chinese herbal medicines have promising clinical efficacies in patients with elevated serum uric acid levels (SMD: −1.65, 95% CI: −3.09 to −0.22; p = 0.024). There was no significant difference in serum uric acid levels between Chinese herbal medicine treatments and Western medicine treatments (SMD: −0.13, 95% CI: −0.99 to 0.74; p = 0.772). Experimental studies revealed that the mechanistic signaling pathways involved in the serum uric acid lowering effects include uric acid synthesis, uric acid transport, inflammation, renal fibrosis and oxidative stress. Conclusions. The clinical studies indicate that Chinese herbal medicines lower serum uric acid levels. Further studies with sophisticated research design can further demonstrate the efficacy and safety of these Chinese herbal medicines in lowering serum uric acid levels and reveal a comprehensive picture of the underlying mechanisms of action.

Particulate matter (PM10) as a newly identified environmental risk factor for acute gout flares: A time-series study

OBJECTIVES

This study aimed to investigate the effect of short-term exposure to ambient particulate matter less than 10μm in diameter (PM₁₀) on occurrence of acute gout flares in the general population and identify susceptible groups accordingly.

METHODS

The data of emergency department (ED) cases with acute gout flare in Incheon city, Korea between January 1st 2008 and December 31st 2015 were collected from the National Health Insurance Service claims data. The levels of PM₁₀ and meterological measurements were provided by the Ministry of Environment and the National Meterological Office, respectively. To estimate the risk of daily ED visits due to acute gout flare, these time-series data set were analyzed using generalized additive models with Poisson distribution, including daily average PM₁₀ level, temperature, relative humidity, day of the week, national holiday, season, and date.

RESULTS

The risk of daily ED visits for acute gout flares per interquartile range increment of the average daily PM₁₀ levels significantly increased in the cumulative lag 0-7 model (relative risk, 1.018; 95% confidence interval, 1.008-1.027, P<0.001). In particular, men aged≥40 years and those with a history of diabetes mellitus or gout were significantly at a high risk of acute gout flares by subgroup analysis.

CONCLUSIONS

Our time-series study demonstrated a modest, but significant effect of short-term exposure to PM₁₀ on ED visits for acute gout flares. Ambient PM₁₀ may be a newly identified environmental risk factor for acute gout flares.

A Randomized Internet-Based Pilot Feasibility and Planning Study of Cherry Extract and Diet Modification in Gout

OBJECTIVE

The aim of this study was to conduct a 9-month pilot Internet randomized controlled trial (RCT) of cherry extract and diet modification in gout to assess the feasibility of an Internet study and obtain effect estimates.

METHODS

After providing online informed consent in response to Internet advertisements and social media or clinic flyers, 84 people with physician-confirmed gout were randomized to either cherry extract 3,600 mg/d (n = 41) or dietitian-assisted diet modification for gout (n = 43). All study outcomes were collected via Internet and phone calls. The primary objective was the feasibility of an Internet study, and secondary objectives were to obtain effect estimates for gout flares, functional ability assessed with the Health Assessment Questionnaire (HAQ), and adverse events (AEs) for future trials.

RESULTS

Of the 84 people randomized, overall completion rates were more than 80% for most study procedures up to 6 months and similar for the 2 active comparators. Improvements were seen in gout flares and HAQ scores in cherry extract and diet modification groups at 9 months compared with baseline: gout flares per month, 0.22 versus 0.36 (p = 0.049) and 0.28 versus 0.31 (p = 0.76); proportion with any gout flare, 56% versus 98% (p < 0.0001) and 65% versus 98% (p = 0.0002); and mean ± standard deviation HAQ score, 0.28 ± 0.54 versus 0.55 ± 0.68 (p = 0.001) and 0.23 ± 0.40 versus 0.48 ± 0.61 (p = 0.06), respectively. Any AEs and gastrointestinal symptoms/AEs at 9 months in cherry extract and diet modification groups were 3% versus 0% and 28% versus 27%, respectively.

CONCLUSIONS

An Internet gout RCT is feasible for nonpharmacological gout treatments. A hypothesis-testing, large Internet RCT of cherry extract versus placebo is needed.

Impact of Lesinurad and allopurinol on experimental Hyperuricemia in mice: biochemical, molecular and Immunohistochemical study

BACKGROUND

Hyperuricemia is an abnormal increase in uric acid levels in the blood. It is the cause of gout that manifested by inflammatory arthritis and painful disable. Therefore, current study evaluated the potential ameliorative impact of Lesinurad and Allopurinol on the kidneys of hyperuricemic mice at the biochemical, molecular and cellular levels.

METHODS

Lesinurad and allopurinol alone or in combination were orally administered to hyperuricemic and control mice for seven consecutive days. Levels of uric acid and blood urea nitrogen, along with antioxidants and inflammatory cytokines (IL-1β and TNF-α) were measured in the serum. The mRNA expression of mouse urate anion transporter-1, glucose transporter 9, organic anion transporters, in renal tissues were examined using quantitative real time PCR. Simultaneously, the immunoreactivity of transforming growth factor-beta 1 was examined immunohistochemically.

RESULTS

Lesinurad and allopurinol administration resulted in significant decrease in serum levels of uric acid, blood urea nitrogen, xanthine oxidase activity, catalase, glutathione peroxidase and inflammatory cytokines (IL-1β and TNF-α) reported in hyperuricemic mice. Both partially reversed oxonate-induced alterations in renal mURAT-1, mGLUT-9, mOAT-1 and mOAT-3 expressions, as well as alterations in the immunoreactivity of TGF- β1, resulting in the increase of renal uric acid secretion and excretion. The combined administration of lesinurad and ALP restored all altered parameters in a synergistic manner, improving renal function in the hyperuricemic mouse model employed.

CONCLUSION

This study confirmed synergistic ameliorative hypouricemic impact of both lesinurad and allopurinol in the treatment of hyperuricemia in mice at the biochemical, molecular and cellular levels.

Effects of Highly Oxygenated Water in a Hyperuricemia Rat Model

Recent years have seen a rapidly rising number of oxygenated water brands that claim to impart health benefits and increase athletic performance by improving oxygen availability in the body. Drinks with higher dissolved oxygen concentrations have in recent times gained popularity as potential ergogenic aids, despite the lack of evidence regarding their efficacy. The aim of this study was to characterize oxygenated water and assess the improvement in uric acid metabolism while identifying performance enhancements in animals administered oxygenated water. Oxygenated water was characterized by hydrogen and oxygen nuclear magnetic resonance (NMR) spectroscopy. Hyperuricemia in rats was induced by treatment with oxonic acid potassium salt, and the animals were given oxygenated drinking water before, during, or after oxonic acid treatment. Serum uric acid was measured to confirm the effects on uric acid metabolism. Following oxygenation, the full width at half maximum (FWHM) was reduced to 11.56 Hz and 64.16 Hz in the hydrogen and oxygen NMR spectra, respectively. Oxygenated water molecule clusters were reduced in size due to the reduction in FWHM. Oxygen concentration did not vary significantly with increased temperature. However, standing time played a critical role in the amount of oxygen dissolved in the water. The rat studies indicated that oxygenated water reduced serum uric acid levels and their rate of increase and enhanced uric acid metabolism. A significant improvement in uric acid metabolism and rate of increase in serum uric acid concentration was observed in hyperuricemic rats administered oxygenated water compared to that in rats administered regular water. High oxygen concentrations enhanced the rate of oxygen absorption, leading to increased glycolysis and mitochondrial protein synthesis. Therefore, oxygenated water is a potential adjuvant therapy or health food for treatment of hyperuricemia.

Aqueous and Methanol Extracts of Paullinia pinnata (Sapindaceae) Improve Monosodium Urate-Induced Gouty Arthritis in Rat: Analgesic, Anti-Inflammatory, and Antioxidant Effects

The profound modification of lifestyle and food habits has led to an important increase in the prevalence of gout. Unfortunately, there are current unmet needs for the treatment of this disease, prompting the search for new alternatives. Paullinia pinnata is a plant used to treat various diseases including arthritis. The present work aimed to investigate the antigouty activities of the aqueous (AEPP) and methanolic (MEPP) extracts of P. pinnata as well as their in vivo antioxidant properties. The gouty arthritis was induced by injecting 50 μl of monosodium urate (MSU, 100 mg/ml) in the left hind ankle of rats. P. pinnata extracts were administered orally at the doses of 100 and 200 mg/kg/day for 6 days, starting 24 h after MSU injection. Allopurinol 5 mg/kg/day was used as reference drug. Inflammation and hyperalgesia were daily monitored from 24 hours after treatment initiation and for the 6 consecutive days. Myeloperoxidase (MPO) quantification was done in collected synovial fluid. Nitrite oxide (NO), malondialdehyde (MDA), and superoxide dismutase (SOD) were evaluated in the spinal cord and the brain. The serum content of SOD was additionally quantified. AEPP and MEPP significantly (p < 0.001) reduce MSU-induced inflammation (22.41% to 93.65%) and hyperalgesia (33.33% to 64.44%) in both ankle and paw. AEPP and MEPP significantly (p < 0.001) reduce synovial MPO production with the percentage ranging from 76.30% to 85.19%. AEPP and MEPP significantly (p < 0.001) reduce serum, spinal, left and right hemispheres NO, and MDA and increase the SOD activity (p < 0.001). P. pinnata leaf extracts possess potent curative effects against MSU-induced gouty arthritis that combines analgesic, anti-inflammatory, and antioxidant activities. These findings support the use of P. pinnata leaves extracts in the treatment of gouty arthritis and further present the plant as a potent source of efficient antigouty medicine.

Colorectal Cancer Among Gout Patients Undergoing Colonoscopy

BACKGROUND/OBJECTIVE

The connection between gout and various cancers remains unclear. We assessed the relationship between gout and colorectal cancer in a population of veterans.

METHODS

We reviewed the Computerized Patient Record System of the VA New York Harbor Health Care System to assess the 10-year occurrence of colorectal cancer in patients with gout undergoing colonoscopy, versus patients with osteoarthritis but no gout.

RESULTS

Gout and osteoarthritis subjects were similar in age, ethnicity, body mass index, and smoking history. Among 581 gout and 598 osteoarthritis subjects with documented colonoscopies, the 10-year prevalence of colorectal cancer was significantly lower in gout (0.8%) versus osteoarthritis (3.7%) (p = 0.0008) patients. Differences in colorectal cancer rates remained significant after stratifying for nonsteroidal anti-inflammatory drug use. Among gout subjects, use of colchicine and/or allopurinol, as well as the presence/absence of concomitant osteoarthritis, did not influence colorectal cancer occurrence. On subanalysis, differences in colorectal cancer occurrence between gout and osteoarthritis subjects persisted among those who underwent diagnostic (0.5% in gout vs 4.6% in osteoarthritis subjects, p < 0.001) but not screening (0.9% in gout subjects vs 1% in osteoarthritis subjects, p = 1.0) colonoscopy. There was no significant difference in nonmalignant colorectal polyp occurrence between gout and osteoarthritis subjects.

CONCLUSIONS

Subjects with gout had decreased colonoscopy-documented occurrence of colorectal cancer compared with osteoarthritis subjects, suggesting a possible protective effect.

Polydatin and Resveratrol Inhibit the Inflammatory Process Induced by Urate and Pyrophosphate Crystals in THP-1 Cells

Resveratol (RES) and its natural precursor polydatin (PD) are polyphenols that may display a broad variety of beneficial effects including anti-inflammatory properties. This study aimed to investigate the role of RES and PD in the inflammatory process induced by monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals in vitro. A monocytic cell line (THP-1) was primed for 3 hours with phorbol myristate acetate (100 ng/mL) and stimulated with synthetic MSU (0.05 mg/mL) and CPP (0.025 mg/mL) crystals. RES and PD were added to cultures concurrently with the crystals, or as 2-hour pretreatment. The effect of the two polyphenols was evaluated on intracellular and extracellular IL-1β levels, NACHT-LRRPYD-containing protein-3 (NLRP3) inflammasome expression, reactive oxygen species (ROS) and nitric oxide (NO) production, and the assessment of crystal phagocytosis. RES and PD strongly inhibited IL-1β induced by crystals after cell pretreatment. Cell pretreatment was effective also in reducing IL-1 mRNA expression while no effect was observed on NLRP3 gene expression. RES and PD had no effect on crystal phagocytosis when used as pretreatment. Both polyphenols were significantly effective in inhibiting ROS and NO production. Our results demonstrated that RES and PD are effective in inhibiting crystal-induced inflammation. Data obtained after cell pretreatment allow us to hypothesize that these polyphenols act on specific signaling pathways, preventing inflammation.

Serum Oxidative Stress Markers are not Associated with Renal and Common Carotid Arteries Arteriosclerotic Vascular Changes in Patients with Gout

Objective: To establish the association between serum levels of reactive oxygen species (ROS) products, nitric oxide (NO) radicals and ascorbate radicals with renal resistive index (RRI), common carotid artery resistive index (CCARI) and intima-media thickness (IMT) in gout patients, and to find out whether the connection is more pronounced when tophi are present.

Methods: A cross-sectional study including 71 consecutive gout patients, divided into two groups according to the presence of subcutaneous tophi. Serum concentrations of ROS products, NO radicals and ascorbate radicals were determined by ex vivo electron paramagnetic resonance (EPR) study. RRI was measured in both kidneys at the level of interlobar arteries with 3.5 MHz transducer. By applying ultrasound of the common carotid arteries, conducted with 10 MHz linear transducer CCARI and IMT were measured.

Results: Gouty arthritis without tophi and gouty tophi subjects were age-matched. Serum uric acid and distribution of conventional cardiovascular risk factors was equal in the groups. However, in tophi patients CRP and the number of individuals who had suffered a cardiovascular event were higher. In the two stages of the disease serum levels of ROS products, NO radicals, ascorbate radicals, as well as RRI and CCARI were comparable but intima-media was thicker in gouty tophi. Serum concentrations of ROS products, NO radicals and ascorbate radicals did not correlate with RRI, CCARI and IMT. Among untreated and treated with Allopurinol or Febuxostat patients the means of ROS products, NO radicals, ascorbate radicals, RRI, CCARI and IMT were similar.

Conclusions: In the earlier and advanced stage of the disease we found no difference in oxidative stress level but the degree of inflammation was higher in tophi subjects. No connection was established between serum ROS products, NO radicals and ascorbate radicals with renal and carotid arteries arteriosclerotic vascular changes. We suggest that in gout individuals intrinsic inflammation has a leading role in the process of atherogenesis.

Is there a role for cherries in the management of gout?

Despite the availability of effective urate-lowering therapy (ULT) and anti-inflammatory drugs for the treatment of gout, there is considerable interest in novel treatment approaches. Patients with gout often have a multitude of comorbidities, leading to concern over drug–drug interactions and medication adverse events. The cherry is a small nutrient-rich fruit that has garnered a great deal of attention in recent years as a nonpharmacologic option for the treatment of a multitude of disease manifestations. Perhaps a quarter of patients with gout try cherries or cherry products to treat their gout, which have antioxidant and anti-inflammatory (IL-6, TNF-α, IL-1β, IL-8, COX-I and -II) properties, hypouricemic effects, and the ability to downregulate NFkB-mediated osteoclastogenesis. Based on these properties, cherries may reduce both the acute and chronic inflammation associated with recurrent gout flares and its chronic destructive arthropathy. In this review, we explore the potential benefits of cherries and cherry products as a nonpharmacologic option for the treatment of gout.

Common gene variants interactions related to uric acid transport are associated with knee osteoarthritis susceptibility

BACKGROUND

The presence of genetic variants in uric acid (UA) transporters can be associated with hyperuricemia, and therefore with an increased risk of monosodium urate (MSU) crystal precipitation. The inflammatory process triggered by these crystals leads to cartilage damage, which, in turn, could promote knee osteoarthritis (KOA).

OBJECTIVE

To determine whether genetic polymorphisms of the UA transporters and their interactions are associated with KOA.

MATERIALS AND METHODS

Two hundred forty-three unrelated Mexican-mestizo individuals were recruited for this case-control study. Ninety-three of them were KOA patients but without gout, and one hundred and fifty healthy individuals with no symptoms or signs of KOA were recruited as controls. Forty-one single-nucleotide polymorphisms (SNPs) involved in the UA transporters were genotyped with OpenArray technology in a QuantStudio 12K flex-System with both cases and controls.

RESULTS

After adjusting by age, gender, BMI, and ancestry, significant associations were found for eight SNPs: rs1260326 (GCKR), rs780093 (GCKR), rs17050272 (INHBB), rs1471633 (PDZK1), rs12129861 (PDZK1), rs7193778 (IGF1R), rs17786744 (STC1), and rs1106766 (R3HDM2). With respect to gene-gene interactions, the pairwise interactions of rs112129861 (PDZK1) and rs7193778 (IGF1R); rs17050272 (INHBB) and rs1106766 (R3HDM2); rs1106766 (R3HDM2) and rs780093 (GCKR); rs1260326 (GCKR) and rs17786744 (STC1); and rs17786744 (STC1) and rs1106766 (R3HDM2) make it possible to visualize the synergistic or antagonistic effect of their genotypes or alleles on KOA development.

CONCLUSIONS

Our preliminary results show that the common gene variants related to UA transport are associated with KOA in the Mexican population. Further studies must be carried out to corroborate it.

[Ru(bpy)2(NO)SO3](PF6), a Nitric Oxide Donating Ruthenium Complex, Reduces Gout Arthritis in Mice

Monosodium urate crystals (MSU) deposition induces articular inflammation known as gout. This disease is characterized by intense articular inflammation and pain by mechanisms involving the activation of the transcription factor NFκB and inflammasome resulting in the production of cytokines and oxidative stress. Despite evidence that MSU induces iNOS expression, there is no evidence on the effect of nitric oxide (NO) donors in gout. Thus, the present study evaluated the effect of the ruthenium complex donor of NO {[Ru(bpy)₂(NO)SO₃](PF₆)} (complex I) in gout arthritis. Complex I inhibited in a dose-dependent manner MSU-induced hypersensitivity to mechanical stimulation, edema and leukocyte recruitment. These effects were corroborated by a decrease of histological inflammation score and recruitment of Lysm-eGFP⁺ cells. Mechanistically, complex I inhibited MSU-induced mechanical hypersensitivity and joint edema by triggering the cGMP/PKG/ATP-sensitive K (+) channels signaling pathway. Complex I inhibited MSU-induced oxidative stress and pro-inflammatory cytokine production in the knee joint. These data were supported by the observation that complex I inhibited MSU-induced NFκB activation, and IL-1β expression and production. Complex I also inhibited MSU-induced activation of pro-IL-1β processing. Concluding, the present data, to our knowledge, is the first evidence that a NO donating ruthenium complex inhibits MSU-induced articular inflammation and pain. Further, complex I targets the main physiopathological mechanisms of gout arthritis. Therefore, it is envisaged that complex I and other NO donors have therapeutic potential that deserves further investigation.

Monocyte to Lymphocyte Ratio, Neutrophil to Lymphocyte Ratio, and Red Cell Distribution Width are the Associates with Gouty Arthritis

BACKGROUND

Neutrophils, monocytes, and macrophages activations are associated with a gout attack. Monocyte to lymphocyte ratio (MLR), neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), red cell distribution width (RDW), and mean platelet volume (MPV) are well-known inflammation markers. In this study, we aimed to investigate whether they could be a predictive marker to the gout attack.

MATERIAL AND METHODS

A hundred and ten gout patients (male/female, 86/24) and 90 (male/female, 64/26) age-, gender-, and body mass index-matched volunteer controls were included in the study. Blood samples were obtained in the intercritical and attack period of the patients. Hemogram, serum uric acid (SUA), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) values were studied.

RESULTS

In the attack period NLR (p < 0.001), PLR (p < 0.05), MLR (p < 0.001), RDW (p < 0.05), MPV (p < 0.05), ESR (p < 0.001), CRP (p < 0.001) and SUA (p < 0.001) values were significantly higher than intercritical period values. According to the results of regression analysis; There was an independent strong relationship between the gout attack and SUA, (Beta [β] = 0.352, p < 0.001), ESR (β = 0.329, p < 0.001), CRP (β = 0.286, p < 0.001), MLR (β = 0.126, p < 0.001), RDW (β = 0.100, p = 0.003) and NLR (β = 0.082, p = 0.014).

CONCLUSIONS

MLR, RDW, and NLR may be a strong predictive marker for a gout attack. MPV and PLR values in the gout attack may be associated with systemic inflammation.

Hesperidin Methylchalcone Suppresses Experimental Gout Arthritis in Mice by Inhibiting NF-κB Activation

Gout arthritis is a painful inflammatory disease induced by monosodium urate (MSU) crystals. We evaluate the therapeutic potential of the flavonoid hesperidin methylchalcone (HMC) in a mouse model of gout arthritis induced by intra-articular injection of MSU (100 μg/10 μL). Orally given HMC (3-30 mg/kg, 100 μL) reduced in a dose-dependent manner the MSU-induced hyperalgesia (44%, p < 0.05), edema (54%, p < 0.05), and leukocyte infiltration (70%, p < 0.05). HMC (30 mg/kg) inhibited MSU-induced infiltration of LysM-eGFP⁺ cells (81%, p < 0.05), synovitis (76%, p < 0.05), and oxidative stress (increased GSH, FRAP, and ABTS by 62, 78, and 73%, respectively; reduced O₂^- and NO by 89 and 48%, p < 0.05) and modulated cytokine production (reduced IL-1β, TNF-α, IL-6, and IL-10 by 35, 72, 37, and 46%, respectively, and increased TGF-β by 90%, p < 0.05). HMC also inhibited MSU-induced NF-κB activation (41%, p < 0.05), gp91^phox (66%, p < 0.05) and NLRP3 inflammasome components mRNA expression in vivo (72, 77, 71, and 73% for NLRP3, ASC, pro-caspase-1, and pro-IL-1 β, respectively, p < 0.05), and induced Nrf2/HO-1 mRNA expression (3.9- and 5.1-fold increase, respectively, p < 0.05). HMC (30, 100, and 300 μM) did not inhibit IL-1β secretion by macrophages primed by LPS and challenged with MSU (450 μg/mL), demonstrating that the anti-inflammatory effect of HMC in gout arthritis depends on inhibiting NF-κB but not on direct inhibition of inflammasome. The pharmacological effects of HMC indicate its therapeutic potential for the treatment of gout.

ABCG2 contributes to the development of gout and hyperuricemia in a genome-wide association study

Although many genome-wide association studies (GWASs) of hyperuricemia or gout have been reported, the related genetic factors and the mechanisms from hyperuricemia to gouty attack remain unclear. This study aimed to identify genetic factors and pathogenesis of gout from hyperuricemia by genome-wide association study (GWAS). 747 gout patients, 747 hyperuricemia and 2071 age-matched controls were recruited and analyzed with Affymetrix 650 K chip to find the related genetic variants. The functions of the related genes were investigated in an endothelial cell (EC) with urate crystal stimulation. The GWAS results showed 36 SNPs to be strongly associated with gout compared to controls (all p-values < 10⁻⁷). Whereas the rs2231142 in ABCG2 gene had significant associations between gout and controls, between gout and hyperuricemia, and between hyperuricemia and controls (all p-values < 10⁻⁷), and the ORs were 4.34, 3.37 and 2.15 (all p-values < 0.001) after adjustment of potential confounders, respectively. The cell model showed significantly higher IL-8 release from EC combined with ABCG2 knockdown. We concluded that ABCG2 gene contributed to hyperuricemia but also gout, and that it was involved in the inflammation dysregulation via augmented IL-8 release in EC.

Neck Circumference, a Novel Indicator for Hyperuricemia

Background: Waist circumference has been correlated with the risk of hyperuricemia. Whether neck circumference is also associated with hyperuricemia has not been assessed. This study aimed to investigate whether neck circumference is associated with hyperuricemia.

Methods: This study population from Beijing is part of the larger China-wide Risk Evaluation of Cancers in Chinese Diabetic Individuals: a lONgitudinal (REACTION) study. For this Beijing sub-center cross-sectional study, a total of 8971 subjects were recruited. Gender-specific multivariable-adjusted regression analyses were conducted to analyze the association of neck circumference and waist circumference with hyperuricemia and the association of neck circumference with serum uric acid levels in the non-hyperuricemia population.

Results: After adjusting for confounding variables, regression analyses showed that neck circumference was positively associated with hyperuricemia [OR, 2.61 (1.86–3.67) for males and 3.27 (2.53–4.22) for females] in both genders; further, neck circumference was also positively associated with serum uric acid levels in non-hyperuricemia subjects [b, 2.58 (1.76–3.39) for males and 4.27 (3.70–4.84) for females] in both genders. Additionally, we demonstrated that neck circumference was similar to waist circumference in terms of the strength of association (OR, 3.03 for waist circumference vs. 2.61 for neck circumference in males, and 3.50 vs. 3.27 for females) with hyperuricemia and the ability to predict hyperuricemia (AUC, 0.63 for waist circumference vs. 0.61 for neck circumference in males, and 0.66 vs. 0.66 in females).

Conclusion: Neck circumference is positively and independently associated with hyperuricemia in both genders and is also associated with serum uric acid levels in the non-hyperuricemia population.

Fructose Consumption, Lipogenesis, and Non-Alcoholic Fatty Liver Disease

Increased fructose consumption has been suggested to contribute to non-alcoholic fatty liver disease (NAFLD), dyslipidemia, and insulin resistance, but a causal role of fructose in these metabolic diseases remains debated. Mechanistically, hepatic fructose metabolism yields precursors that can be used for gluconeogenesis and de novo lipogenesis (DNL). Fructose-derived precursors also act as nutritional regulators of the transcription factors, including ChREBP and SREBP1c, that regulate the expression of hepatic gluconeogenesis and DNL genes. In support of these mechanisms, fructose intake increases hepatic gluconeogenesis and DNL and raises plasma glucose and triglyceride levels in humans. However, epidemiological and fructose-intervention studies have had inconclusive results with respect to liver fat, and there is currently no good human evidence that fructose, when consumed in isocaloric amounts, causes more liver fat accumulation than other energy-dense nutrients. In this review, we aim to provide an overview of the seemingly contradicting literature on fructose and NAFLD. We outline fructose physiology, the mechanisms that link fructose to NAFLD, and the available evidence from human studies. From this framework, we conclude that the cellular mechanisms underlying hepatic fructose metabolism will likely reveal novel targets for the treatment of NAFLD, dyslipidemia, and hepatic insulin resistance. Finally, fructose-containing sugars are a major source of excess calories, suggesting that a reduction of their intake has potential for the prevention of NAFLD and other obesity-related diseases.

Fructose Intake, Serum Uric Acid, and Cardiometabolic Disorders: A Critical Review

There is a direct relationship between fructose intake and serum levels of uric acid (UA), which is the final product of purine metabolism. Recent preclinical and clinical evidence suggests that chronic hyperuricemia is an independent risk factor for hypertension, metabolic syndrome, and cardiovascular disease. It is probably also an independent risk factor for chronic kidney disease, Type 2 diabetes, and cognitive decline. These relationships have been observed for high serum UA levels (>5.5 mg/dL in women and >6 mg/dL in men), but also for normal to high serum UA levels (5-6 mg/dL). In this regard, blood UA levels are much higher in industrialized countries than in the rest of the world. Xanthine-oxidase inhibitors can reduce UA and seem to minimize its negative effects on vascular health. Other dietary and pathophysiological factors are also related to UA production. However, the role of fructose-derived UA in the pathogenesis of cardiometabolic disorders has not yet been fully clarified. Here, we critically review recent research on the biochemistry of UA production, the relationship between fructose intake and UA production, and how this relationship is linked to cardiometabolic disorders.

Naringenin Inhibits Superoxide Anion-Induced Inflammatory Pain: Role of Oxidative Stress, Cytokines, Nrf-2 and the NO-cGMP-PKG-KATP Channel Signaling Pathway

In the present study, the effect and mechanism of action of the flavonoid naringenin were evaluated in superoxide anion donor (KO₂)-induced inflammatory pain in mice. Naringenin reduced KO₂-induced overt-pain like behavior, mechanical hyperalgesia, and thermal hyperalgesia. The analgesic effect of naringenin depended on the activation of the NO−cGMP−PKG−ATP-sensitive potassium channel (K_ATP) signaling pathway. Naringenin also reduced KO₂-induced neutrophil recruitment (myeloperoxidase activity), tissue oxidative stress, and cytokine production. Furthermore, naringenin downregulated KO₂-induced mRNA expression of gp91phox, cyclooxygenase (COX)-2, and preproendothelin-1. Besides, naringenin upregulated KO₂-reduced nuclear factor (erythroid-derived 2)-like 2 (Nrf2) mRNA expression coupled with enhanced heme oxygenase (HO-1) mRNA expression. In conclusion, the present study demonstrates that the use of naringenin represents a potential therapeutic approach reducing superoxide anion-driven inflammatory pain. The antinociceptive, anti-inflammatory and antioxidant effects are mediated via activation of the NO−cGMP−PKG−K_ATP channel signaling involving the induction of Nrf2/HO-1 pathway.