Cytokine Profile in Gout: Inflammation Driven by IL-6 and IL-18?

Targeting Myeloperoxidase Ameliorates Gouty Arthritis: A Virtual Screening Success Story

This study presents a new approach for identifying myeloperoxidase (MPO) inhibitors with strong in vivo efficacy. By combining inhibitor-like rules and structure-based virtual screening, the pipeline achieved a 70% success rate in discovering diverse, nanomolar-potency reversible inhibitors and hypochlorous acid (HOCl) scavengers. Mechanistic analysis identified RL6 as a genuine MPO inhibitor and RL7 as a potent HOCl scavenger. Both compounds effectively suppressed HOCl production in cells and neutrophils, with RL6 showing a superior inhibition of neutrophil extracellular trap release (NETosis). In a gout arthritis mouse model, intraperitoneal RL6 administration reduced edema, peroxidase activity, and IL-1β levels. RL6 also exhibited oral bioavailability, significantly reducing paw edema when administered orally. This study highlights the efficacy of integrating diverse screening methods to enhance virtual screening success, validating the anti-inflammatory potential of potent inhibitors, and advancing the MPO inhibitor research.

Transdermal delivery of iguratimod and colchicine ethosome by dissolving microneedle patch for the treatment of recurrent gout

This study introduces a novel approach of repetitive modeling to simulate the pathological process of recurrent gout attacks in humans. This methodology addresses the instability issues present in rat models of gout, providing a more accurate representation of the damage recurrent gout episodes inflict on human skeletal systems. A soluble nanoneedle system encapsulating colchicine and iguratimod ethosomal formulations was developed. This system aims to modulate inflammatory cytokines and inhibit osteoclast activity, thereby treating inflammatory pain and bone damage associated with recurrent gout. Additionally, a comprehensive evaluation of the microneedles' appearance, morphology, mechanical properties, and penetration capability confirmed their effectiveness in penetrating the stratum corneum. Dissolution tests and skin irritation assessments demonstrated that these microneedles dissolve rapidly without irritating the skin. In vitro permeation studies indicated that transdermal drug delivery via these microneedles is more efficient and incurs lower drug loss compared to traditional topical applications. In vivo pharmacodynamic assessments conducted in animal models revealed significant analgesic and anti-inflammatory effects when both types of microneedles were used together. Further analyses, including X-ray imaging, hematoxylin and eosin (H&E) staining, Safranin-O/fast green staining, tartrate-resistant acid phosphatase staining, and quantification of osteoclasts, confirmed the bone-protective effects of the microneedle combination. In conclusion, the findings of this research underscore the potential of this novel therapeutic approach for clinical application in the treatment of recurrent gout.

Systemic inflammatory cytokine profiles in patients with gout during flare, intercritical and treat-to-target phases: TNFSF14 as new biomarker

INTRODUCTION

Untreated gout is characterised by monosodium urate (MSU) crystal accumulation responsible for recurrent flares that are commonly separated by asymptomatic phases. Both phases are inflammatory conditions of variable intensity. Gout flares are self-limited inflammatory reactions involving multiple mediators. This study aimed to characterise the inflammatory profiles of gout at different phases.

METHODS

Using the Olink targeted proteomics, levels of 92 inflammation-related proteins were measured in plasma samples of a prospective gout population (GOUTROS), collected at gout flare (T1), the intercritical phase (T2) and after reaching the target serum urate level under urate-lowering therapy (T3). Results were validated in an independent cohort (OLT1177-05) with plasmas collected at T1 and T2. Ex vivo and in vitro experiments were performed to assess the inflammatory properties of new biomarkers.

RESULTS

In total, 21 inflammatory new biomarkers were differentially expressed during the three time-points of gout disease. The levels of four of these proteins (interleukin 6 (IL-6), colony-stimulating factor 1, vascular endothelial growth factor A and tumour necrosis factor superfamily 14 (TNFSF14)) were increased during gout flare in an independent cohort. IL-6 and TNFSF14 had the highest fold change in expression during T1 versus T2 or T3. TNFSF14 was produced at the inflamed joint and enhanced the inflammatory response induced by lipopolysaccharide and MSU crystal stimulation. Conversely, TNFSF14 blockade reduced the inflammatory response. Additionally, single nucleotide polymorphisms of TNFSF14 affected the ability of myeloid cells to produce inflammatory cytokines.

CONCLUSION

Gout flare involves multiple inflammatory mediators that may be used as potential therapeutic targets.

To Investigate the Mechanism of Qinpi Tongfeng Formula in Treating Acute Gouty Arthritis by UHPLC-Q-Orbitrap-MS, Network Pharmacology and Experimental Validation

Background

Acute gouty arthritis (AGA) is characterized by the accumulation of monosodium urate crystals within the joints, leading to inflammation and severe pain. Western medicine treatments have limitations in addressing this condition. Previous studies have shown the efficacy of Qinpi Tongfeng formula (QPTFF) in treating AGA, but further investigation is needed to understand its mechanism of action.

Methods

We used ultra-high-performance liquid chromatography tandem Q-Exactive Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap-MS) to identify compounds in QPTFF. Target proteins regulated by these compounds were obtained from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform, Chemistry Database, and Swiss Target Prediction Database. AGA-related targets were searched and screened from various databases, including Genecards, PharmGKB, Drugbank, etc. Intersection targets of QPTFF and AGA were analyzed for protein-protein interaction networks, GO function enrichment, and KEGG pathway enrichment. We then verified QPTFF's mechanism of action using an AGA rat model, assessing pathological changes via H&E staining and target expression via ELISA, RT-qPCR, and Western blot.

Results

UHPLC-Q-Orbitrap-MS identified 207 compounds in QPTFF, with 55 selected through network pharmacology. Of 589 compound-regulated targets and 1204 AGA-related targets, 183 potential targets were implicated in QPTFF's treatment of AGA. Main target proteins included IL-1β, NFKBIA, IL-6, TNF, CXCL8, and MMP9, with the IL-17 signaling pathway primarily regulated by QPTFF. Experimental results showed that medium and high doses of QPTFF significantly reduced serum inflammatory factors and MMP-9 expression, and inhibited IL-17A, IL-6, IKK-β, and NF-κB p65 mRNA and protein expression in AGA rats compared to the model group.

Conclusion

Key targets of QPTFF include IL-1β, NFKBIA, IL-6, TNF-α, CXCL8, and MMP9. QPTFF effectively alleviates joint inflammation in AGA rats, with high doses demonstrating no liver or kidney toxicity. Its anti-inflammatory mechanism in treating AGA involves the IL-17A/NF-κB p65 signaling pathway.

Deficiency of histone deacetylases 3 in macrophage alleviates monosodium urate crystals-induced gouty inflammation in mice

BACKGROUND

Gout is caused by monosodium urate (MSU) crystals deposition to trigger immune response. A recent study suggested that inhibition of Class I Histone deacetylases (HDACs) can significantly reduce MSU crystals-induced inflammation. However, which one of HDACs members in response to MSU crystals was still unknown. Here, we investigated the roles of HDAC3 in MSU crystals-induced gouty inflammation.

METHODS

Macrophage specific HDAC3 knockout (KO) mice were used to investigate inflammatory profiles of gout in mouse models in vivo, including ankle arthritis, foot pad arthritis and subcutaneous air pouch model. In the in vitro experiments, bone marrow-derived macrophages (BMDMs) from mice were treated with MSU crystals to assess cytokines, potential target gene and protein.

RESULTS

Deficiency of HDAC3 in macrophage not only reduced MSU-induced foot pad and ankle joint swelling but also decreased neutrophils trafficking and IL-1β release in air pouch models. In addition, the levels of inflammatory genes related to TLR2/4/NF-κB/IL-6/STAT3 signaling pathway were significantly decreased in BMDMs from HDAC3 KO mice after MSU treatment. Moreover, RGFP966, selective inhibitor of HDAC3, inhibited IL-6 and TNF-α production in BMDMs treated with MSU crystals. Besides, HDAC3 deficiency shifted gene expression from pro-inflammatory macrophage (M1) to anti-inflammatory macrophage (M2) in BMDMs after MSU challenge.

CONCLUSIONS

Deficiency of HDAC3 in macrophage alleviates MSU crystals-induced gouty inflammation through inhibition of TLR2/4 driven IL-6/STAT3 signaling pathway, suggesting that HDAC3 could contribute to a potential therapeutic target of gout.

Elevated serum IL-2 and Th17/Treg imbalance are associated with gout

Gout is considered an auto-inflammatory disorder, and the immunological drivers have not been fully unraveled. This study compared the peripheral lymphocyte and CD4+T cell subsets, and cytokines in gout and healthy controls (HCs) to explore the contributions of T helper 17 (Th17) cells, T regulatory (Treg) cells and cytokines to the pathogenesis of gout. We enrolled 126 gout patients (53 early-onset gout with age of first presentation < 40 years, and 73 late-onset gout with age of first presentation ≥ 40 years) and 77 HCs. Percentage and absolute numbers of peripheral lymphocyte and CD4+T cell subpopulations in each group were detected by flow cytometry. The serum cytokine levels were determined by flow cytometric bead array. For circulating CD4+T cell subsets, Th17/Treg ratio was significantly higher in early-onset gout, late-onset gout and gout without tophus than HCs; Th17 cells were significantly elevated in early-onset gout and gout without tophus, while the percentage of Treg cells was significantly decreased in early-onset and late-onset gout. Additionally, gout patients had significantly higher cytokines levels (including IL-2, IL-4, IL-6, IL-10, IL-17, IFN-γ, and TNF-α) than HCs; IL-2 levels were positively correlated with Treg cells and negatively correlated with ESR. ROC analysis showed that disease duration, CRP and fibrinogen, had moderate predictive performances for tophus in gout (the AUCs were 0.753, 0.703 and 0.701, respectively). Our study suggests that early-onset and late-onset gout differ in Th17/Treg imbalance, which in early-onset gout is due to elevated Th17 cells and in late-onset gout is due to decreased Treg cells. And increased serum cytokine levels, especially IL-2, may play an essential role in that. Restoring Th17/Treg balance may be a crucial way to improve the prognosis of gout patients.

Prevalence and treatment rate of gout by depressive symptom severity: A cross-sectional analysis of NHANES 2007-2018

BACKGROUND

The co-disease of depression and gout is becoming more common in the modern era. However, the relationship between the severity of depressive symptoms and gout prevalence and treatment rate was still unclear.

OBJECTIVE

This study aimed to determine the relationship between the prevalence, treatment rate of gout, and the severity of depression in the United States.

METHOD

The cross-sectional analysis of the 2007-2018 National Health and Nutrition Examination Survey (NHANES) for participants with depression was performed. According to their Patient Health Questionnaire-9 (PHQ-9) scores, participants were categorized as none, mild, moderate, moderately severe, and severe. To learn the correlation between the severity of depressive symptoms and the prevalence and treatment rate of gout using multivariate logistic regression to control for confounder interference.

RESULTS

A total of 25 022 patients were included in this study. As the severity of the depressive symptoms worsened (Mild, Moderate and Moderately severe), the risk of gout increased in non-adjusted model and model 1,2,3 (p-value for trend =.01 in non-adjusted model, <.0001 in model 1, <.01 in models 2 and 3; prevalence group in Model 1, aOR1.71, 95% CI (1.40, 2.08) in the mild group, aOR1.68, 95% CI (1.19, 2.39) in the moderate group, aOR1.31,95% CI (0.82, 2.11) in the moderately severe group, aOR1.21, 95% CI (0.62, 2.38) in the severe group). However, the lower gout prevalence trend has no statistical significance after adjusting all factors in Model 4(p-value for trend =.98). Compared with patients without depression, only a few patients received treatment, especially patients with severe depression (none, 80.1%; severe, 0.2%). The more severe the depression, the lower the treatment rate (p-value for trend: non-adjusted model, p < .001; model 1, p = .05; model 2, p = .02; model 3, p = .03).

CONCLUSION

Compared with patients without depression, the patients with depression had a higher risk of gout. With the aggravation of depression, the prevalence of gout and the rate of treatment both were decreased. Patients with gout and depression need to receive multidisciplinary care after diagnosis. However, currently, treatment cannot meet the needs of the current patients.

Immune and inflammatory mechanisms and therapeutic targets of gout: An update

Gout is an autoimmune disease characterized by acute or chronic inflammation and damage to bone joints induced due to the precipitation of monosodium urate (MSU) crystals. In recent years, with the continuous development of animal models and ongoing clinical investigations, more immune cells and inflammatory factors have been found to play roles in gouty inflammation. The inflammatory network involved in gout has been discovered, providing a new perspective from which to develop targeted therapy for gouty inflammation. Studies have shown that neutrophil macrophages and T lymphocytes play important roles in the pathogenesis and resolution of gout, and some inflammatory cytokines, such as those in the interleukin-1 (IL-1) family, have been shown to play anti-inflammatory or proinflammatory roles in gouty inflammation, but the mechanisms underlying their roles are unclear. In this review, we explore the roles of inflammatory cytokines, inflammasomes and immune cells in the course of gout development and the research status of therapeutic drugs used for inflammation to provide insights into future targeted therapy for gouty inflammation and the direction of gout pathogenesis research.

Increased Metallothionein-1 Associated with Gout Activity and Tophi

BACKGROUND AND AIMS

Gout is a chronic self-limiting inflammatory arthritis. An increase in metallothionein-1 (MT-1) has been reported in rheumatoid arthritis and osteoarthritis, and it attenuates inflammation and the pathology of diseases. This study aims to detect MT-1 levels in patients with gout and to explore its correlation with disease activity, clinical indexes, and inflammatory cytokines.

METHODS

The expression of MT-1 messenger RNAs (mRNAs) and protein levels in patients with gout were measured using real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Correlations between MT-1 and clinical indexes or inflammatory mediators were analyzed using Spearman's correlation test.

RESULTS

Compared with healthy controls (HCs, n = 43), patients with active gout (n = 27) showed higher levels of MT-1 mRNA in peripheral blood mononuclear cells and protein in serum, particularly those with tophi. No significant difference in serum MT-1 levels was observed among patients with inactive gout, HCs, and patients with hyperuricemia without gout. Furthermore, no significant difference was observed between patients with gout with kidney damage and HCs. In addition, serum interleukin (IL)-1β, IL-6, and IL-8 levels were significantly increased in patients with active gout, particularly in those with tophi. The serum MT-1 level was positively correlated with C-reactive protein, as well as with IL-1β, IL-6, and IL-18.

CONCLUSION

The higher levels of MT-1 were found in patients with gout, which were correlated with disease activity and gout related pro-inflammatory cytokines. Indicating MT-1 may serve as a new marker for predicting disease activity.Abbreviations: IL-1β: Interleukin 1β; MT-1: Metallothionein-1; CRP: C-Reactive Protein; ROS: Reactive Oxygen Species; IL-10: Interleukin 10; TGF-β: Transforming Growth Factor Beta.

Changes of serum uric acid level during acute gout flare and related factors

OBJECTIVE

By studying the changes of serum uric acid (SUA) in acute stage and remission stage of gouty arthritis, we aimed to explore the relationship between the changes of SUA level and free glucocorticoids and inflammatory factors.

METHODS

A prospective, longitudinal study was conducted on 50 acute gout patients in the dedicated gout clinic of the Affiliated Hospital of Qingdao University. Blood and 24-hour urine samples were collected during the acute phase and two weeks after the initial visit. Patients with acute gouty arthritis were treated primarily with colchicine and nonsteroidal anti-inflammatory drugs.

RESULTS

A total of 32 patients completed the two-week follow-up trial. SUA levels were significantly downregulated during the acute flare than after the flare (464.14 ± 90.97 vs. 527.36 ± 86.90 μmol/L, p < 0.001). The 24-hour fractional excretion of uric acid (24 h FEur) (5.54 ± 2.82% vs. 4.68 ± 2.83%, p < 0.001) and 24-hour urinary uric acid excretion (24 h Uur) (663.08 ± 249.48 μmol/L vs. 540.87 ± 263.18 μmol/L, p = 0.001) increased significantly in patients during the acute phase. The percent change in SUA was associated with those in 24 h FEur and C-reactive protein. Meanwhile, the percent change in 24 h Uur was associated with those in 24-hour urinary free cortisol, percent change in interleukin 1β and interleukin 6.

CONCLUSION

Decreased SUA level during the acute gout flare was associated with increased excretion of urinary uric acid. Inflammatory factors and bioactive free glucocorticoids may play significant roles in this process.

Joint Application of Multiple Inflammatory Cytokines in Diagnosis of Gout Flare

Purpose

This study aimed to explore the accuracy for joint application of inflammatory cytokines in diagnosis of gout flare by comparison with peripheral blood cells.

Methods

We collected the clinical data of 96 acute gout patients and 144 remission gout patients, and compared the levels of peripheral blood cells, inflammatory cytokines and blood biochemistry indexes between acute and remission gout. We respectively assessed the area under curves (AUCs) for single and multiple inflammatory cytokines including C-reactive protein (CRP), interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), and single and multiple peripheral blood cells including platelet (PLT), white blood cell (WBC), percentages of neutrophils (N%), lymphocytes (L%), eosinophils (E%), basophils (B%) in diagnosis of acute gout by receiver operating characteristic (ROC) curve analysis.

Results

By contrast with remission gout, the levels of PLT, WBC, N%, CRP, IL-1β, IL-6 and TNF-α increased, and the levels of L%, E% and B% decreased in acute gout. The AUCs of PLT, WBC, N%, L%, E% and B% in diagnosis of acute gout were respectively 0.591, 0.601, 0.581, 0.567, 0.608 and 0.635, while the AUC for joint application of these peripheral blood cells was 0.674. Moreover, the AUCs of CRP, IL-1β, IL-6 and TNF-α in diagnosis of acute gout were respectively 0.814, 0.683, 0.622 and 0.746, while the AUC for joint application of these inflammatory cytokines was 0.883, reflecting significantly higher levels than peripheral blood cells.

Conclusion

The joint application of multiple inflammatory cytokines can better distinguish acute gout from remission gout compared with peripheral blood cells.

Lipidomics analysis facilitate insight into the molecular mechanisms of urate nephropathy in a gout model induced by combination of MSU crystals injection and high-fat diet feeding

Renal injury is one of the most common clinical manifestations of patients with hyperuricaemia/gout. The precise pathophysiological mechanism(s) for the renal injury is still unknown. Furthermore, it is also unclear whether the clinical therapies (e.g., colchicine and febuxostat) could prevent its progression or not. Lipids are involved in almost all of important biological processes and play critical roles in maintaining the renal functions. Herein, shotgun lipidomics was performed for class-targeted lipid analysis of cellular lipidomes in renal tissue of a gouty model induced by combination of monosodium urate crystals injection and high-fat diet feeding with/without treatment with either colchicine or febuxostat. Serum uric acid (UA), proinflammatory cytokines (i.e., TNF-α and IL-6), xanthine oxidase activity, footpad swelling, and pain threshold were determined to evaluate the gouty severity. Renal histopathological changes, blood urea nitrogen, creatinine, and kidney index were used to reflect renal injury. Lipidomics analysis revealed that altered triacylglycerol (TAG) profile, impaired mitochondrial function resulted by decreased tetra 18:2 cardiolipin, reduced 4-hydroxyalkenal (HNE) species, and elevated lysophospholipids were already present in the kidneys at early stage of renal injury, probably contributing to its occurrence and development. In addition to significantly reduce the UA level and relief the gouty severity, treatment with either colchicine or febuxostat could restore HNE bioavailability, thereby delaying the progression of renal injury. However, both of them could not recover the altered TAG profile and the impaired mitochondrial function, indicating that treatment with either of them could not completely prevent the development of renal injury in the gouty model.

Integrating network pharmacology and experimental validation to clarify the anti-hyperuricemia mechanism of cortex phellodendri in mice

Hyperuricemia (HUA), a common metabolic disease, is treated as the second-largest metabolic disease after diabetes in China. Cortex Phellodendri (CP) is one of the most frequently used herbal medicines for treating gout or HUA. However, the mechanism underlying the anti-HUA effect of CP is still unrevealed. Hence, this study aimed to explore the pharmacological mechanism of CP against HUA using network pharmacology coupled with in vivo experimental validation. Active compounds and potential targets of CP, as well as the potential targets related to HUA, were retrieved from multiple open-source databases. The drug-disease overlapping targets were obtained by Venn diagram analysis and used to construct the herb-component-target (HCT), protein-protein-interaction (PPI), and component-target-pathway (CTP) networks. The functional enrichment analysis was also performed for further study. Furthermore, a HUA mouse model was induced by a combination of intraperitoneal injection of potassium oxonate (PO, 300 mg/kg) and intragastric administration of hypoxanthine (HX, 300 mg/kg) daily for 10 days. Different dosages of CP (200, 400, and 800 mg/kg) were orally given to mice 1 h after modeling. The results showed that 12 bioactive compounds and 122 drug-disease overlapping targets were obtained by matching 415 CP-related targets and 679 HUA-related targets, and berberine was one of the most important compounds with the highest degree value. The core targets of CP for treating HUA were TP53, MAPK8, MAPK3, IL-6, c-Jun, AKT1, xanthine oxidase (XOD), and ATP-binding cassette subfamily G member 2 (ABCG2). The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment results showed that the anti-HUA effect of CP mainly involved the pathways of inflammation and apoptosis, such as PI3K/Akt, TNF, MAPK, TLR, AMPK, NF-κB, and NLRP3 signaling pathways. In vivo animal experiment further confirmed the hypouricemic effect of CP in a HUA mouse model, as evidenced by significantly restored kidney histological deteriorations, and considerably decreased levels of serum uric acid (sUA), creatinine (Cre), blood urea nitrogen (BUN), and hepatic UA. Furthermore, the hypouricemic action of CP in vivo might be attributed to its suppression of XOD activity in the liver, rather than ABCG2 in the kidney. Real-time qPCR (RT-qPCR) and Western blot analysis also confirmed the key roles of the hub genes in CP against HUA. In conclusion, CP exhibited therapeutic effect against HUA via multi-compounds, multi-targets, and multi-pathways. It possessed anti-HUA and nephroprotective effects via suppressing XOD activity, and reversed the progression of renal injury by exerting anti-inflammatory and anti-apoptotic effects.

Transcriptomic analysis of the anti-inflammatory effect of Cordyceps militaris extract on acute gouty arthritis

Background: Gouty arthritis (GA) is a common inflammatory disease that causes pain due to the deposition of monosodium urate (MSU) crystals into joints and surrounding tissues. Anti-inflammatory drugs have significant clinical anti-inflammatory and analgesic effects, but they have many side effects. Cordyceps militaris is an edible and medicinal fungus, and its extract (CME) has good anti-inflammatory and analgesic effects. This study aimed to investigate the anti-inflammatory effect of CME on GA and its underlying mechanism.

Methods: The effect of CME on the expression of related inflammatory factors and histopathological changes in the MSU-induced acute inflammatory gout model in rats was studied by ELISA and HE, and its anti-inflammatory mechanism was analyzed by transcriptome combined with RT-qPCR.

Results: CME significantly improved gait scores and joint swelling in GA rats, and reduced MSU-induced inflammatory cell infiltration. CME inhibited MSU-induced inflammatory responses by reducing the levels of pro-inflammatory factors TNF-α, IL-1β, IL-6, and Caspase-1 and increasing the anti-inflammatory factor IL-10. Transcriptome analysis showed that CME significantly altered inflammation-related cytokine pathways, and identified four major genes involved in regulation of inflammation, CCL7, CSF2RB, LIF, and IL-1β. In addition, RT-qPCR was performed to verify these differential genes.

Conclusion: CME significantly alleviated the inflammatory progression of GA and ameliorated the onset of GA. The underlying mechanism may be related to triggering the cytokine-cytokine receptor interaction signaling pathway to inhibit the activation of the inflammasome and regulate the immune system. And it regulates the inflammatory response induced by MSU crystals through the genes CCL7, CSF2RB, and IL-1β.

Environmental factors and risk of gout

Gout is a chronic disease with inflammatory arthritis caused by monosodium urate (MSU) crystals deposition, an elevated serum urate level (hyperuricaemia) is the critical factor leading to MSU crystals deposition and promoting the progression of gout. The onset and development of gout is generally the result of multiple factors, such as diet, heredity and environmental factors. Although genetics and diet are thought to play as major factors, a growing body of research evidence has highlighted that environmental factors also play a significant role in the onset and exacerbation of gout. Recent studies have shown that air pollutants such as particulate matter, sulfur dioxide (SO₂) and carbon monoxide (CO) may increase the risk of hospitalizations for gout, and that the changes in temperature and humidity may affect uric acid (UA) levels. There is also seasonal trend in gout. It has been demonstrated that environmental factors may induce or accelerate the production and release of pro-inflammatory mediators, causing an unbalance oxidative stress and systemic inflammation, and then participating in the overall process or a certain link of gout. Moreover, several environmental factors have shown the ability to induce the production urate and regulate the innate immune pathways, involving in the pathogenesis of gout. Nevertheless, the role of environmental factors in the etiology of gout remains unclear. In this review, we summarized the recent literatures and aimed to discuss the relationship between environmental factors (such as microclimate, season, ambient/indoor air pollution and extreme weather) and gout. We further discussed the inflammatory mechanisms of environmental factors and gout and the comprehensive effects of environmental factors on gout. We also made a prospect of the management and treatment of gout, with special consideration to environmental factors associated with gout.

Exploring the mechanism of action of dapansutrile in the treatment of gouty arthritis based on molecular docking and molecular dynamics

Purpose: Dapansutrile is an orally active β-sulfonyl nitrile compound that selectively inhibits the NLRP3 inflammasome. Clinical studies have shown that dapansutrile is active in vivo and limits the severity of endotoxin-induced inflammation and joint arthritis. However, there is currently a lack of more in-depth research on the effect of dapansutrile on protein targets such as NLRP3 in gouty arthritis. Therefore, we used molecular docking and molecular dynamics to explore the mechanism of dapansutrile on NLRP3 and other related protein targets.

Methods: We use bioinformatics to screen active pharmaceutical ingredients and potential disease targets. The disease-core gene target-drug network was established and molecular docking was used for verification. Molecular dynamics simulations were utilized to verify and analyze the binding stability of small molecule drugs to target proteins. The supercomputer platform was used to measure and analyze the binding free energy, the number of hydrogen bonds, the stability of the protein target at the residue level, the radius of gyration and the solvent accessible surface area.

Results: The protein interaction network screened out the core protein targets (such as: NLRP3, TNF, IL1B) of gouty arthritis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that gouty arthritis mainly played a vital role by the signaling pathways of inflammation and immune response. Molecular docking showed that dapansutrile play a role in treating gouty arthritis by acting on the related protein targets such as NLRP3, IL1B, IL6, etc. Molecular dynamics was used to prove and analyze the binding stability of active ingredients and protein targets, the simulation results found that dapansutrile forms a very stable complex with IL1B.

Conclusion: We used bioinformatics analysis and computer simulation system to comprehensively explore the mechanism of dapansutrile acting on NLRP3 and other protein targets in gouty arthritis. This study found that dapansutrile may not only directly inhibit NLRP3 to reduce the inflammatory response and pyroptosis, but also hinder the chemotaxis and activation of inflammatory cells by regulating IL1B, IL6, IL17A, IL18, MMP3, CXCL8, and TNF. Therefore, dapansutrile treats gouty arthritis by attenuating inflammatory response, inflammatory cell chemotaxis and extracellular matrix degradation by acting on multiple targets.

Palmatine Protects Against MSU-Induced Gouty Arthritis via Regulating the NF-κB/NLRP3 and Nrf2 Pathways

Purpose

Gouty arthritis could be triggered by the deposition of monosodium uric acid (MSU) crystals. Palmatine (PAL), a protoberberine alkaloid, has been proven to possess compelling health-beneficial activities. In this study, we aimed to explore the effect of PAL on LPS plus MSU crystal-stimulated gouty arthritis in vitro and in vivo.

Methods

PMA-differentiated THP-1 macrophages were primed with LPS and then stimulated with MSU crystal in the presence or absence of PAL. The expression of pro-inflammatory cytokines and oxidative stress-related biomarkers and signal pathway key targets were determined by ELISA kit, Western blot, immunohistochemistry and qRT-PCR, respectively. In addition, the anti-inflammatory and antioxidant activities of PAL on MSU-induced arthritis mice were also evaluated.

Results

The results indicated that PAL (20, 40 and 80 μM) dose-dependently decreased the mRNA expression and levels of pro-inflammatory cytokines (interleukin-1beta (IL-1β), IL-6, IL-18 and tumor necrosis factor alpha (TNF-α)). The levels of superoxide dismutase (SOD) and glutathione (GSH) were remarkably enhanced, while the level of malondialdehyde (MDA) was reduced. Western blot analysis revealed that PAL appreciably inhibited NF-κB/NLRP3 signaling pathways through inhibiting the phosphorylation of p-65 and IκBα, blocking the expression of NLRP3, ASC, IL-1β and Caspase-1, as well as enhancing the antioxidant protein expression of Nrf2 and HO-1. In vivo, PAL attenuated MSU-induced inflammation in gouty arthritis, as evidenced by mitigating the joint swelling, and decreasing the productions of IL-1β, IL-6, IL-18, TNF-α and MDA, while enhancing the levels of SOD and GSH. Moreover, PAL further attenuated the infiltration of neutrophils into joint synovitis.

Conclusion

PAL protected against MSU-induced inflammation and oxidative stress via regulating the NF-κB/NLRP3 and Nrf2 pathways. PAL may represent a potential candidate for the treatment of gouty arthritis.

The Role of Inflammasomes in Osteoarthritis and Secondary Joint Degeneration Diseases

Osteoarthritis is age-related and the most common form of arthritis. The main characteristics of the disease are progressive loss of cartilage and secondary synovial inflammation, which finally result in pain, joint stiffness, and functional disability. Similarly, joint degeneration is characteristic of systemic inflammatory diseases such as rheumatoid arthritis and gout, with the associated secondary type of osteoarthritis. Studies suggest that inflammation importantly contributes to the progression of the disease. Particularly, cytokines TNFα and IL-1β drive catabolic signaling in affected joints. IL-1β is a product of inflammasome activation. Inflammasomes are inflammatory multiprotein complexes that propagate inflammation in various autoimmune and autoinflammatory conditions through cell death and the release of inflammatory cytokines and damage-associated molecule patterns. In this article, we review genetic, marker, and animal studies that establish inflammasomes as important drivers of secondary arthritis and discuss the current evidence for inflammasome involvement in primary osteoarthritis. The NLRP3 inflammasome has a significant role in the development of secondary osteoarthritis, and several studies have provided evidence of its role in the development of primary osteoarthritis, while other inflammasomes cannot be excluded. Inflammasome-targeted therapeutic options might thus provide a promising strategy to tackle these debilitating diseases.

"In silico identification of ethoxy phthalimide pyrazole derivatives as IL-17A and IL-18 targeted gouty arthritis agents"

Two proinflammatory cytokines, IL17A and IL18, are observed to be elevated in the serum of gout patients and they play a crucial role in the development and worsening of inflammation, which has severe effects. In present study, we have combined molecular docking, molecular dynamics studies and MM-PBSA analysis to study the effectiveness of ethoxy phthalimide pyrazole derivatives (series 3a to 3e) as potential inhibitors against cytokines IL17A and IL18 as a druggable targets. The binding energy of the docked series ranges from -13.5 to -10.0 kcal/mol and extensively interacts with the amino acids in the active pocket of IL17A and IL18. Compound 3e had the lowest binding energy with IL17A at -12.6 kcal/mol compared to control allopurinol (3.32 kcal/mol). With IL18, compound 3a seems to have the lowest binding energy of -9.6 kcal/mol compared to control allopurinol (3.18 kcal/mol). In MD simulation studies, compound 3a forms a stable and energetically stabilized complex with the target protein. Depending on properties of the bound IL17A-3a and IL18-3a complexes was compared by means of MM-PBSA analysis. These derivatives can be used as a scaffold to develop promising IL17A and IL18 inhibitors to assess their potential for gouty arthritis and other related diseases.

(-)-Epicatechin Ameliorates Monosodium Urate-Induced Acute Gouty Arthritis Through Inhibiting NLRP3 Inflammasome and the NF-κB Signaling Pathway

Background: Gouty arthritis is a common and complex inflammatory disease that will reduce the life quality of human beings (-)-Epicatechin (EC) is famous for antioxidant and anti-inflammatory activities. Thus, the aim of this study was to investigate the therapeutic effect of EC on gouty arthritis and its mechanisms. Methods and results: EC was added into a monosodium urate (MSU)-stimulated THP-1 cell that was induced by phorbol 12-myristate 13-acetate and lipopolysaccharide (LPS) in advance to establish a gout model in vitro. The efficiency of EC on acute gouty arthritis mice induced by MSU was further investigated. The results showed that EC concentration-dependently improved the cell viability of LPS and MSU stimulated THP-1 cells, and significantly alleviated MSU-induced ankle edema in mice in a dose-dependent manner. In addition, EC inhibited the infiltration of inflammatory cells and local cascular congestion in ankle joint tissue. Furthermore, the secretion of inflammatory cytokines (IL-1β, IL-18, IL-6, and TNF-α) activation of NLRP3 inflammasome and NF-κB signaling pathway were markedly suppressed by EC in vitro and in vivo. Conclusion: These results indicated that EC could effectively improve MSU-induced acute gouty arthritis via inhibiting NLRP3 inflammasome and the NF-κB signaling pathway in vitro and in vivo, which suggested that EC might be a promising active ingredient for the prevention and treatment of gouty arthritis.

Relationship between hyperuricemia with deposition and sexual dysfunction in males and females

PURPOSE

The association between gout, the most common crystal arthropathy, and sexual dysfunctions has often been investigated by studies in the last decades. Despite the presence of shared risk factors and comorbidities and the possible effects on sexual health of long-term gout complications, awareness of this association is severely lacking and the pathogenetic mechanisms have only partially been identified. In the present review, we aimed to investigate the current evidence regarding the potential mechanisms linking sexual dysfunctions and gout.

METHODS

A comprehensive literature search within PubMed was performed to provide a summary of currently available evidence regarding the association between gout and sexual dysfunctions.

RESULTS

Gout and sexual dysfunctions share several risk factors, including diabesity, chronic kidney disease, hypertension, metabolic syndrome, and peripheral vascular disease. Gout flares triggered by intense inflammatory responses feature severe pain and disability, resulting in worse sexual function, and some, but not all, treatments can also impair sexual health. Long-term gout complications can result in persistent pain and disability due to joint deformity, fractures, or nerve compression, with negative bearing on sexual function. The presence of low-grade inflammation impairs both sex steroids synthesis and endothelial function, further advancing sexual dysfunctions. The psychological burden of gout is another issue negatively affecting sexual health.

CONCLUSIONS

According to currently available evidence, several biological and psychological mechanisms link sexual dysfunctions and gout. Addressing risk factors and providing adequate treatment could potentially have beneficial effects on both conditions. Appropriate clinical evaluation and multidisciplinary approach are recommended to improve patient care.

Effects of β-Carotin and Green Tea Powder Diets on Alleviating the Symptoms of Gouty Arthritis and Improving Gut Microbiota in C57BL/6 Mice

As a chronic metabolic disease caused by disorders of purine metabolism, gout has shown increasing incidence rate worldwide. Considering that gout is not easily treated and cured, further studies are explored to prevent gout development through diet modification. Both β-carotin and green tea powder are rich in dietary fiber, which helps maintain the balance of gut microbiota in humans. The aim of this study was to investigate the effects of β-carotin and green tea powder diet on the prevention of gouty arthritis in relation to the bacterial structure of gut microbiota in mice. We successfully induced gouty arthritis in C57BL/6 mice by injecting monosodium urate (MSU) crystals and feeding high-fat diet (HFD), and further investigated the effects of additional β-carotin and green tea powder in the diets of mice on the prevention of gouty arthritis in mice. Our results showed that diet of β-carotin and green tea powder reduced the joint swelling and pain in mice with gout, reduced the levels of serum uric acid (UA) and three types of pro-inflammatory cytokines, i.e., interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), improved the gut microbiota profile, and reduced the metabolic levels of purines and pyrimidines. In conclusion, our study provided evidence to support the application of β-carotin and green tea powder diet as a dietary adjustment method to prevent and treat gouty arthritis.

Biochemical and molecular effects of a commercial diuretic with herbal extract on experimentally induced urolithiasis in chickens

This study evaluated the diuretic, antioxidant, anti-inflammatory, and immunological effects of a commercial diuretic (CD) (composed of ammonium chloride, potassium citrate, sodium chloride, ascorbic acid, biotin, halfa bar extract, and hexamine) on chickens with induced urolithiasis. A total of 100 one-day-old white Hy-Line chicks were fed a basal diet containing 20% crude protein (CP) and 1% Ca until they reached 48 days of age. Then, the birds were divided into five groups (G1-G5). G1 was fed a basal diet and kept as a negative control, G2 was fed a high protein (HP) diet containing 25% crude protein, G3 was fed high calcium (HC) diet containing 5% Ca, G4 was fed HP diet supplemented with CD, and G5 was fed HC diet supplemented with CD. The CD was supplemented with drinking water (at a dose of 0.5 ml/ liter) for 1 week. The experiment was held for 78 days. Clinical signs, postmortem lesions, and mortality rates were observed. Biochemical analytes, redox status biomarkers, and expression of interleukin-6 (IL-6) and interferon-gamma (IFN-γ) were measured. Tissue samples were taken for histopathological examination. No signs of CD toxicity were observed during the toxicity test prior to the experiment. Compared to all groups, birds in G2 and G3 showed impaired renal function and alterations in biochemical, redox status, lipid peroxidation, post-mortem, and histopathological lesions along with upregulation of IL-6 and IFN-γ in the kidney and spleen. In conclusion, commercial diuretic supplementation for one week improves renal function, redox status, immune and anti-inflammatory responses in chickens with induced urolithiasis.

Uric Acid in Inflammation and the Pathogenesis of Atherosclerosis

Hyperuricemia is a common metabolic syndrome. Elevated uric acid levels are risk factors for gout, hypertension, and chronic kidney diseases. Furthermore, various epidemiological studies have also demonstrated an association between cardiovascular risks and hyperuricemia. In hyperuricemia, reactive oxygen species (ROS) are produced simultaneously with the formation of uric acid by xanthine oxidases. Intracellular uric acid has also been reported to promote the production of ROS. The ROS and the intracellular uric acid itself regulate several intracellular signaling pathways, and alterations in these pathways may result in the development of atherosclerotic lesions. In this review, we describe the effect of uric acid on various molecular signals and the potential mechanisms of atherosclerosis development in hyperuricemia. Furthermore, we discuss the efficacy of treatments for hyperuricemia to protect against the development of atherosclerosis.

The biology of urate

Urate is the end-product of the purine metabolism in humans. The dominant source of urate is endogenous purines and the remainder comes through diet. Approximately two thirds of urate is eliminated via the kidney with the rest excreted in the feces. While the transporter BCRP, encoded by ABCG2, has been found to play a role in both the gut and kidney, SLC22A12 and SLC2A9 encoding URAT1 and GLUT9, respectively, are the two transporters best characterized. Only 8-12% of the filtered urate is excreted by the kidney. Renal elimination of urate depends substantially on specific transporters, including URAT1, GLUT9 and BCRP. Studies that have assessed the biologic effects of urate have produced highly variable results. Although there is a suggestion that urate may have anti-oxidant properties in some circumstances, the majority of evidence indicates that urate is pro-inflammatory. Hyperuricemia can result in the formation of monosodium urate (MSU) crystals that may be recognized as danger signals by the immune system. This immune response results in the activation of the NLRP3 inflammasome and ultimately in the production and release of interleukin-1β, and IL-18, that mediate both inflammation, pyroptotic cell death, and necroinflammation. It has also been demonstrated that soluble urate mediates effects on the kidney to induce hypertension and can induce long term epigenetic reprogramming in myeloid cells to induce "trained immunity." Together, these sequelae of urate are thought to mediate most of the physiological effects of hyperuricemia and gout, illustrating this biologically active molecule is more than just an "end-product" of purine metabolism.

Interleukin-18 in Brazilian Rheumatoid Arthritis Patients: Can Leflunomide Reduce It?

OBJECTIVES

Rheumatoid arthritis affects about 1% of the world's population. This is a chronic autoimmune disease. It is predominant in females with progressive joint damage. Immune cells are involved, especially Th1/Th17 lymphocytes and their inflammatory cytokines. These proteins have different functions in the immune system, such as IL-16 is a chemotactic factor; IL-18 can activate NFκB transcription producing inflammatory proteins; IL-31 can activate the JAK/STAT pathway which leads to the production of inflammatory factors in chronic diseases; IL-33 promotes IL-16 secretion which causes lymphocyte recruitment, and IL-32 and IL-34 appear to increase TNF secretion by macrophages activation in AR. The aim of this study was to evaluate serum levels of IL-16, IL-18, IL-31, IL-32, IL-33, and IL-34 and compare them with the severity and treatment of RA patients if there are any correlations.

METHODS

A total of 140 RA patients and 40 healthy donors were recruited from the Department of Rheumatology at Hospital das Clínicas from the Federal University of Pernambuco. 60 AR patients were naïve for any treatment. Serum cytokine levels were determined using an ELISA kit.

RESULTS

Serum IL-16 (p = 0.0491), IL-18 (p < 0.0001), IL-31 (p = 0.0004), and IL-32 (p = 0.0040) levels were significantly increased in RA patients compared with healthy donors. It was observed that patients using leflunomide had the lowest IL-18 levels, close to controls levels (p = 0.0064).

CONCLUSION

IL-16, IL-18, IL-31, and IL-32 are increased in the serum of RA patients. IL-18 is at lower levels in those AR who are taking leflunomide as treatment.

Second-Hand Smoke and Its Synergistic Effect with a Body-Mass Index of >24.9 kg/m2 Increase the Risk of Gout Arthritis in Indonesia

To analyze the association between smoking status (active smoking and exposure to Second-Hand Smoking (SHS)) and the synergistic effect of smoking status and BMI with gout risk, a community-based case-control design was undertaken among 385 participants, including 304 healthy controls and 81 gout patients from seven community health services. Adjusted Odd Ratios (AORs) and 95% Confidence Interval (CIs) of gout for active smoking and SHS were 3.26 (95% CI = 1.07~9.90) and 4.67 (95% CI = 2.18~10.00) compared to non-smokers. Time-dependent manner of active smoking and SHS significantly increased gout risk with AORs and 95% CIs of 5.95 (1.41~25.03) and 10.12 (3.51~29.14). Dose-dependency of active smokers and SHS showed AORs and 95% CIs of 5.15 (1.28~20.63) and 4.37 (1.33~14.28). Smoking 20 cigarettes (one pack) per day for one year is equivalent to one pack-year. Active smoking >20 pack-year and SHS > 26.5 pack-year increased gout risk with AORs and 95% CIs of 7.18 (1.53~33.67) and 9.95 (3.64~27.22). Participants who smoked (active smoking and SHS) and with Body Mass Index (BMI) of > 24.9 kg/m2 synergistically increased gout risk, with an AOR of 9.65 and 95% CI of 3.25~28.65, compared to BMI ≤ 24.9 kg/m2 and non-smoker. Smoking status (active smoking and SHS) and the synergistic effect of smoking status and BMI increased gout risk in Indonesia.

Elevated interleukin-37 associated with tophus and pro-inflammatory mediators in Chinese gout patients

INTRODUCTION

Interleukin-37(IL-37), a natural inhibitor of innate immunity, has been identified to protect against various inflammatory diseases, including monosodium urate (MSU)-induced inflammation. However, the association of IL-37 with clinical indexes and pro-inflammatory mediators in gout patients remains unclear. The aim of this study was to determine IL-37 level in hyperuricemia and gout patients with or without tophus, and to investigate the correlations of IL-37 with clinical indexs such as Uric Acid (UA), CRP(C-reactive protein), Creatinine Clearance Rate (Ccr), Erythrocyte Sedimentation Rate (ESR) and so on, as well as with the pro-inflammatory mediators in serum including Interleukin-1β(IL-1β), Interleukin-6(IL-6) and Interleukin-18(IL-18) from gout patients.

METHODOLOGY

The serum levels of IL-37, IL-1β, IL-6 and IL-18 levels in serum of gout patients were determined by ELISA; the correlations between IL-37 and clinical values or pro-inflammatory mediators in serum of gout were analyzed by Spearman correlation test.

RESULTS

The serum levels of IL-37 were higher in active gout patients than inactive gout patients and HCs, especially in active gout patients with tophus. No significant difference was observed in serum IL-37 levels between hyperuricemia and normal controls. IL-1β, IL-6 and IL-18 levels were significant elevated in gout patients with tophus than those without tophus; Serum IL-37 were positively correlated with CRP and ESR, as well as with IL-1β, IL-6 and IL-18, negatively correlated with Ccr, and not correlated with UA, creatinine (Cr) and triglyceride (TG) in gout patients.

CONCLUSIONS

IL-37 increased in gout patients positively associated CRP and ESR, as well as with proinflammatory mediators IL-1β, IL-6, IL-18, the presence of tophus and chronic kidney disease in gout. It may be a novel marker for predicting this pathology.

Altered distribution and enhanced osteoclastogenesis of mucosal-associated invariant T cells in gouty arthritis

OBJECTIVE

This study was designed to investigate the role of mucosal-associated invariant T (MAIT) cells in gouty arthritis (GA) and their effects on osteoclastogenesis.

METHODS

Patients with GA (n = 61), subjects with hyperuricaemia (n = 11) and healthy controls (n = 30) were enrolled in this study. MAIT cells, cytokines, CD69, programmed death-1 (PD-1) and lymphocyte-activation gene 3 (LAG-3) levels were measured by flow cytometry. In vitro osteoclastogenesis experiments were performed using peripheral blood mononuclear cells in the presence of M-CSF and RANK ligand.

RESULTS

Circulating MAIT cell levels were significantly reduced in GA patients. However, their capacities for IFN-γ, IL-17 and TNF-α production were preserved. Expression levels of CD69, PD-1 and LAG-3 in MAIT cells were found to be elevated in GA patients. In particular, CD69 expression in circulating MAIT cells was increased by stimulation with MSU crystals, suggesting that deposition of MSU crystals might contribute to MAIT cell activation. Interestingly, MAIT cells were found to be accumulated in synovial fluid and infiltrated into gouty tophus tissues within joints. Furthermore, activated MAIT cells secreted pro-resorptive cytokines (i.e. IL-6, IL-17 and TNF-α) and facilitated osteoclastogenesis.

CONCLUSION

This study demonstrates that circulating MAIT cells are activated and numerically deficient in GA patients. In addition, MAIT cells have the potential to migrate to inflamed tissues and induce osteoclastogenesis. These findings provide an important role of MAIT cells in the pathogenesis of inflammation and bone destruction in GA patients.

Impact of the Synbiotics and Urate-Lowering Therapy on Gut Microbiota and Cytokine Profile in Patients with Chronic Gouty Arthritis

The main goal of our study is the impact evaluation of complex urate-lowering therapy with the synbiotic addition on fecal microbiota and cytokine profile in patients with primary gout. During our study, 130 men (mean age 55.5 ± 9.4 years) with gout (duration 7.7 ± 7.1 years) were examined. All patients were divided into two treatment groups. The main group (n = 68) was taking allopurinol at 300 mg per day dose and additionally a synbiotic. The comparison group (n = 62) received allopurinol monotherapy without synbiotic intake. The therapy duration was 3 months. Evaluation of therapy efficiency was marked by blood uric acid changes, cytokine levels, CRP and fecal microbiota condition. After treatment, stabilization of the gut microbiota parameters was observed, which was leading to normalization uricemia levels (40.3% vs. 21%, p <0.01) in the main group patients. Addition of synbiotic to allopurinol leads to a blood uric acid lowering (18.7% vs. 13.3%, p <0.01), CRP reduction (75% vs. 26.3%, p <0.01) as well as decrease of cytokines level: IL-1β, IL-6, IL-8, IL-10 and TNFα (all p <0.001). After a 3-month gout treatment, a group of patients who received complex therapy with synbiotic inclusion showed signs of disease remission characterized by inflammation activity reducing, fecal microbiota condition normalization and a more pronounced decrease in laboratory markers comparing to control group.

Role of plasma fibrinogen in assessing disease activity of patients with gout

BACKGROUND

Gout is an inflammatory disease characterized by the deposition of monosodium urate (MSU) in synovial fluid and other tissues. Many studies have shown that the activation of coagulation system had been proposed correlated with systemic inflammation. The concentrations of plasma fibrinogen and D-dimer are increased in abnormal coagulation, emerging as available indicators to predict systemic inflammation. The aim of this study is to reveal the predictive value of plasma fibrinogen, D-dimer in the disease activity of gout patients.

METHODS

This retrospective study included 334 gout patients and 101 age- and gender- matched healthy controls. The gout patients were divided into two groups according to the gout activity score (GAS = 0.09 × last 12 month attacks + 1.01 × sUA + 0.34 × VAS patient + 0.53 × ln(1 + tophi number). The remission group included 46 patients with GAS of lower than 2.5 and the active group included 288 patients with GAS of 2.5 or higher. Clinical and laboratory data were recorded. The correlations between plasma fibrinogen, D-dimer and GAS were analyzed by Spearman's correlation analysis and Partial correlation analysis. Receiver operating characteristic (ROC) was used to evaluate the diagnostic value for the active group compared with remission group. The predictive value of fibrinogen, D-dimer to the disease activity of gout patients was tested by Binary logistic regression analysis.

RESULTS

Plasma fibrinogen and D-dimer in gout patients (3.66 (2.88, 5.20), 0.29 (0.22, 0.80)) were increased as compared with the control group (2.88 (2.51, 3.24), 0.22 (0.22, 0.32), both P < 0.001). Fibrinogen and D-dimer in active group (3.91 (3.00, 5.53), 0.34 (0.22, 0.86)) were higher than those in remission group (2.88 (2.34, 3.22), 0.22 (0.22, 0.26), both P < 0.001)). Plasma fibrinogen, D-dimer, ESR and CRP were positively correlated with GAS (r = 0.606, r = 0.419, r = 0.570, r = 0.440, all P < 0.001). ROC curve showed fibrinogen yielded a highest AUC than D-dimer, ESR, CRP. In addition, the optimal cutoff value of fibrinogen for active group was 3.60, with a specificity of 89.1% and sensitivity of 58.3%. Binary logistic regression analysis showed fibrinogen (odds ratio = 2.71, 95% confidence interval: 1.28-5.74, p = 0.011) was a predictor for gout disease activity.

CONCLUSION

Fibrinogen was increased in active gout group. Fibrinogen can serve as a reliable inflammatory marker for monitoring inflammatory response and disease activity in gout patients.

The role of interleukin-1 family members in hyperuricemia and gout

BACKGROUND

Interleukin (IL)-1 family cytokines and their receptors have important roles in innate and partly in adaptive immunity. The family consists of 11 members of which IL-1α, IL-1β, IL-18, IL-33, IL-36α, IL-36β and IL-36γ are considered pro-inflammatory and IL-1Ra, IL-36Ra, IL-37 and IL-38 anti-inflammatory. Whereas IL-1β has a known pivotal role in gout, increasing evidence suggests other IL-1 family members are also involved in the pathogenesis of hyperuricemia and gout flares.

FINDINGS

Studies indicate IL-1α, like IL-1β, plays an essential role in the pathogenesis of gout flares. IL-18, although elevated in patients with gout, does not contribute to MSU crystal-induced inflammation, but may be involved in the subsequent development of cardiovascular disease in individuals with gout. The role of the pro-inflammatory cytokine IL-36 in gout remains elusive. In contrast, IL-1Ra, IL-33, IL-37 and IL-38 inhibit MSU crystal-induced inflammation and therefore have therapeutic potential for treatment of gout flares. In addition to existing IL-1β blockers, several new therapeutics to treat gout are being developed either inhibiting the transcription or maturation of IL-1β.

CONCLUSION

In this review, IL-1 family cytokines are discussed in the context of hyperuricemia and gout. Finally, current and novel therapeutic options for targeting IL-1 are reviewed.

Biliverdin and bilirubin sulfonate inhibit monosodium urate induced sterile inflammation in the rat

BACKGROUND

Biliverdin, a by-product of haem catabolism, possesses potent endogenous antioxidant and anti-inflammatory properties. Bilirubin-C10-sulfonate (BRS), an active metabolite formed after enteral administration of BV in the rat, also possess antioxidant properties. Therefore, we investigated the anti-inflammatory and antioxidant activity of BV and BRS in an in vivo model of monosodium urate induced sterile inflammation.

METHODS

Subcutaneous air pouches were created on the dorsal flanks of Wistar rats (10-12 weeks of age). Prior to stimulation of the 6-day old pouch with monosodium urate (25 mg), groups were pre-treated with intraperitoneal BRS (27 mg/kg) and BV (27 mg/kg). Total and differential leukocyte counts were determined in pouch fluid aspirate at 1, 6, 12, 24 and 48 h after monosodium urate stimulation. Biliverdin (BV), BRS and unconjugated bilirubin (UCB) concentrations in the serum and pouch fluid were quantified using liquid chromatography-mass spectrometry. Pouch fluid cytokine concentrations (IL-1β, IL-1α, TNF-α, IL-17A, IL-12, GM-CSF, IL-33, IFN-γ, IL-18, IL-10, MCP-1, CXCL-1 and IL-6) were assessed after 6 h. In addition, 24 h protein carbonyl and chloramine concentrations were assessed in pouch fluid using ELISA and spectrophotometry, respectively.

RESULTS

BRS and BV significantly (p < 0.05) inhibited leukocyte (total, neutrophil and macrophage) infiltration into the pouch fluid from 6 to 48 h. For example, after 6 h neutrophil counts decreased following BRS (0.32 ± 0.11 × 10⁶ cells mL^-1) and BV (0.17 ± 0.03 × 10⁶ cells mL^-1) compared to MSU only (3.51 ± 1.07 × 10⁶ cells mL^-1). Both BV and BRS significantly (p < 0.05) reduced pouch GM-CSF (BV: 5.8 ± 1.2 pg mL^-1, BRS: 6.9 ± 1.5 pg mL^-1 vs MSU only: 13.0 ± 1.9 pg mL^-1) and MCP-1 concentrations at 6 h (BV: 1804 ± 269 pg mL^-1, BRS: 7927 ± 2668 pg mL^-1 vs MSU only: 17,290 ± 4503 pg ml^-1), whilst BV additionally inhibited IL-6 (4354 ± 977 pg mL^-1 vs MSU only: 25,070 ± 5178 pg mL^-1) and IL-18 (17.6 ± 2.0 pg mL^-1 vs MSU only: 81.5 ± 19.9 pg mL^-1) concentrations at 6 h (p < 0.05). Despite these differences, no change in pouch chloramine or protein carbonyl concentrations occurred at 24 h (p > 0.05). Serum BV concentrations rapidly diminished over 6 h, however, BRS was readily detected in the serum over 48 h, and in pouch fluid over 12 h.

CONCLUSIONS

This study is the first to elucidate anti-inflammatory activity of BRS and the efficacy of BV administration in a model of gouty inflammation. Reduced leukocyte infiltration and cytokine production in response to sterile inflammation further support the importance of these molecules in physiology and their therapeutic potential in sterile inflammation.

Investigation of the Role of Interleukin 6 in Vitiligo Pathogenesis

Interleukin-6 (IL6) is involved in pathogenesis of several autoimmune disorders including vitiligo. Hence, we aimed to investigate the association of IL6 -174 G/C and -572 G/C polymorphisms and its transcript levels with vitiligo; to evaluate the effect of IL-6 on normal human melanocyte (NHM) viability and expression of IL6R, MITF and TYR. IL6 -174 G/C and -572 G/C polymorphisms were genotyped by ARMS-PCR and PCR-RFLP respectively in 343 controls and 322 vitiligo patients. IL6 transcript levels were estimated from PBMCs (96 controls and 77 patients) and skin samples (15 controls and 15 patients) by qPCR. NHM viability was assessed by MTT; IL6R, MITF and TYR transcript and protein levels were monitored by qPCR and ICC respectively. Genetic analyses revealed no association of IL6 -174 G/C polymorphism (p> .05) with vitiligo. Analysis of IL6 -572 G/C revealed reduced risk of vitiligo in individuals with GC/CC genotypes compared to GG genotype (p = .010). IL6 expression was significantly increased (p = .0197) in PBMCs of patients. Further, IL6 expression was significantly higher in non-lesional skin compared to controls (p = .009). In-vitro NHM viability was decreased upon IL-6 exposure (10-50 ng/ml; p< .05), with significantly increased IL6R transcript (p = .042) and protein levels (p = .003) however, MITF transcript (p = .0003) and protein levels (p = .016), and TYR transcript levels (p = .001) were significantly decreased. The results suggest that IL6 -572 G/C polymorphism might be associated with vitiligo susceptibility in Gujarat population. Moreover, increased IL6 expression in vitiligo patients and its effect on NHM suggest a potential role in melanocyte biology.

CONCLUSION

The results suggest that IL6 - 572 G/C polymorphism might be associated with vitiligo susceptibility in Gujarat population. Moreover, increased IL6 expression in vitiligo patients and its effect on NHM suggest a potential role in melanocyte biology.

Biochemical and molecular investigation of oxidative stress associated with urolithiasis induced by increased dietary calcium or protein in chickens

This study was carried out to evaluate the effects of induced urolithiasis by high dietary calcium (Ca) or protein levels on biochemical analyte levels, redox status, selected inflammatory cytokines and histopathology in chickens. A total of 90 one-day-old white Hy-Line chicks were fed basal control diets containing 20% crude protein (CP) and 1% Ca until they reached 44 days of age. After that, the birds were divided into three groups (30 birds per group). All management factors (light, temperature, ventilation, stock density and diet) were identical among the three groups throughout the study except for the dietary Ca and protein percentages. Group I was fed a control diet containing 20% CP and 1% Ca, group II was fed a high-Ca diet containing 5% Ca, and group III was fed a high-protein diet containing 25% CP. Our findings clearly demonstrated that dietary imbalance (caused by high-Ca or high-CP levels) per se in chickens was physiologically harmful, as it was accompanied by post-mortem lesions; biochemical, redox status and histopathological alterations; and upregulation of inflammatory cytokines (interleukin (IL)-1β and IL-6). In particular, the birds fed the high-Ca diet clearly exhibited the most obvious alterations in most of the endpoints. In conclusion, this study constitutes the first extensive investigation of the effects of high-Ca or high-protein diets induced urolithiasis on growth performance, redox status, inflammatory cytokine levels and pathological characterization in chickens.

Cyr61 Promotes Inflammation of a Gouty Arthritis Model in Rats

Background

Cyr61 is considered a novel proinflammatory factor. Gouty arthritis (GA) is a self-limited inflammatory reaction caused by monosodium urate (MSU) crystals. In this study, we assessed the role of Cyr61 in the inflammatory process of GA.

Methods

We investigated the expression of Cyr61 in MSU-induced rat gout models and MSU-stimulated rat fibroblast-like synovial (FLS) cells. After inhibiting the expression of Cyr61, levels of IL-1β, TNF-α, and IL-6 were detected by ELISA, qPCR, western blot, and immunohistochemical methods. We probed the downstream NF-κB signaling pathway using the NF-κB inhibitor PDTC, and levels of NF-κB and p-NF-κB were detected by western blot and qPCR.

Results

Our results demonstrate that Cyr61 plays a potent role in the formation of local inflammation in vitro and in vivo. Cyr61 was highly expressed in synovial tissues of gout models, and the expression of Cyr61 protein was also significantly increased in MSU-stimulated FLS cells. Cyr61 promoted MSU-induced acute inflammation via the NF-κB signaling pathway.

Conclusions

Our study has revealed that Cyr61 is an important regulatory factor for the initiation of inflammation in GA. The high expression of Cyr61 protein can induce synovial cells to produce many inflammatory cytokines, such as IL-1β, TNF-α, and IL-6, partly in an NF-κB-dependent manner. Thus, inhibition of Cyr61 could be a new target and strategy for the prevention and treatment of GA.

Successful Treatment of Covid-19 Associated Cytokine Release Syndrome with Colchicine. A Case Report and Review of Literature

We describe the case of a 42 year old, healthy patient with Covid-19 who despite improvement in his respiratory symptoms developed a mild to moderate cytokine release syndrome (CRS) and an associated monoarticular gout flare. Since the patient refused admission to the hospital and had stable vital signs, we chose to treat him with a safe anti-inflammatory and non-immunosuppressive therapy. To hit two birds with one stone, we considered colchicine, as it has systemic anti-inflammatory effects and is also effective in gout flare. Unexpectedly, 48 hours after treatment, not only did his ongoing fever and toe pain disappear, he also had significant improvements in his general state of health and all his inflammatory markers including fibrinogen, ferritin, D-dimer, and IL-6 levels normalized. To our knowledge, the use of colchicine in Covid-19 and CRS has not been reported. This observation merits the consideration of colchicine as a safe, inexpensive and oral medication for the treatment of mild to moderate CRS in Covid-19 patients. More importantly, in Covid-19 patients with early lung involvement colchicine may be an appropriate candidate to prevent CRS in adjunction with routine antiviral agents. Indeed, multicenter, randomized controlled studies are required to evaluate the benefits of this therapy.

EPS8 regulates an NLRP3 inflammasome-independent caspase-1 activation pathway in monosodium urate crystal-treated RAW264.7 macrophages

Gout is an inflammatory arthritis caused by the phagocytosis of monosodium urate (MSU) crystal deposition in joints. NOD-, LRR-, and pyrin domain-containing 3 (NLRP3) inflammasome-dependent caspase-1 activation is implicated in the processing of interleukin-1β (IL-1β), which is the major effector cytokine in the acute inflammatory response of gout. Mechanisms underlying caspase-1 activation remain unclear. Epidermal growth factor receptor pathway substrate no. 8 (Eps8) is a signal transducer and actin filament organizer that plays a key role in lipopolysaccharide-stimulated phagocytosis in macrophages. Here, RAW264.7 macrophages that have no intact NLRP3 inflammasomes were used to investigate the role of Eps8 in MSU crystal-mediated caspase-1 activation. A kinetic study revealed that the induction of Eps8 expression by MSU crystals occurred before NLRP3, p46/p33 caspase-1, and mature IL-1β in RAW 264.7 cells. In addition, actin cytoskeleton dynamics was required for Eps8 induction and caspase-1 activation in MSU crystal stimulation. Silencing Eps8 had no effect on the basal expression of p46/p33 caspase-1 and NLRP3, but nearly abolished MSU crystal-induced NLRP3 expression and caspase-1 activation. Furthermore, MSU crystals induced Eps8-pro-caspase-1 complex formation and Eps8 formed a stable complex with p33 caspase-1, but not with NLRP3. In summary, our results demonstrated for the first time the importance of Eps8 in MSU crystal-mediated caspase-1 activation without the involvement of NLRP3 inflammasomes.

Dapansutrile, an oral selective NLRP3 inflammasome inhibitor, for treatment of gout flares: an open-label, dose-adaptive, proof-of-concept, phase 2a trial

SUMMARY

BACKGROUND

Gout flares are driven by interleukin (IL)-1β. Dapansutrile inhibits the NLRP3 inflammasome and subsequent activation of IL-1β. In this study we aimed to investigate the safety and efficacy of orally administered dapansutrile in patients with a gout flare.

METHODS

In this open-label, proof-of-concept, phase 2a trial, adult patients (aged 18-80 years) with a monoarticular monosodium urate crystal-proven gout flare were enrolled at an outpatient clinic in the Netherlands and sequentially assigned using a dose-adaptive design to receive 100 mg/day, 300 mg/day, 1000 mg/day, or 2000 mg/day oral dapansutrile for 8 days. The coprimary outcomes were change in patient-reported target joint pain from baseline to day 3 and from baseline to day 7, assessed in the per-protocol population (all patients who received at least 80% of the study drug and had no major protocol deviations). Safety was assessed in the intention-to-treat population. This trial is registered with the EU Clinical Trials Register, EudraCT 2016-000943-14, and is completed.

FINDINGS

Between May 18, 2017, and Jan 21, 2019, 144 patients were assessed for eligibility, of whom 34 were enrolled and 29 were included in the per-protocol population (three patients were excluded due to receiving <80% of study drug and two had major protocol deviations): eight patients received 100 mg/day, seven received 300 mg/day, six received 1000 mg/day, and eight received 2000 mg/day. Between baseline and day 3, there was a mean reduction in patient-reported target joint pain of 52·4% (SD 32·94; p=0∙016) for the 100 mg/day group, 68·4% (34·29; p=0∙016) for the 300 mg/day group, 55·8% (44·90; p=0∙063) for the 1000 mg/day group, and 57·6% (38·72; p=0∙016) for the 2000 mg/day group. At day 7, there was a mean reduction of 82·1% (22·68; p=0∙031) for the 100 mg/day group, 84·2% (16·33; p=0∙016) for the 300 mg/day group, 68·9% (34·89; p=0∙031) for the 1000 mg/day group, and 83·9% (15·44; p=0∙008) for the 2000 mg/day group, compared to baseline. 25 (73·5%) of 34 patients reported a total of 45 treatment-emergent adverse events, most of which were metabolism and nutrition disorders (17 [37·8%]) and gastrointestinal disorders (ten [22·2%]). Two serious adverse events occurred during the study, admission to hospital because of worsening of gout flare at day 3, and admission to hospital because of coronary stenosis 18 days after the patient received their last dose; these were considered moderate in severity and unrelated to the study drug.

INTERPRETATION

Dapansutrile is a specific NLRP3 inflammasome inhibitor with a satisfactory safety profile and efficacy in the reduction of target joint pain in this study. Future studies are needed to confirm the clinical potential of dapansutrile.

Huzhang Tongfeng Granule Improves Monosodium Urate-Induced Inflammation of Gouty Arthritis Rat Model by Downregulation of Cyr61 and Related Cytokines

OBJECTIVE

Gouty arthritis (GA) is a noninfectious inflammatory disease characterized by self-limited and severe pain. Huzhang Tongfeng granule is one of the most effective traditional Chinese medicines in the treatment of acute GA. However, its effects on the inflammatory factors in the process of acute gout inflammation remain unknown. In the present study, we aimed to evaluate the effect of Huzhang Tongfeng granule on the expressions of Cyr61 and related inflammatory factors in both experimental gout models in vivo and in vitro.

METHODS

Huzhang Tongfeng granule was provided by the pharmaceutical preparation room of Yueyang Hospital of Integrated Traditional Chinese and Western Medicine. The expressions of Cyr61, IL-1β, TNF-α, and IL-6 in monosodium urate- (MSU-) induced rat models and fibroblast-like synoviocytes (FLSs) were determined by RT-PCR, Western blotting analysis, ELISA, immunohistochemistry, and hematoxylin and eosin staining.

RESULTS

Huzhang Tongfeng granule could downregulate the expressions of IL-1β, TNF-α, and IL-6 to some extent by inhibiting the expression of Cyr61.

CONCLUSIONS

Collectively, our findings indicated that Cyr61 was highly expressed in rat models of gout. By inhibiting the expression of Cyr61, Huzhang Tongfeng granule could partially attenuate the inflammation induced by MSU crystal.

Uric acid-mediated inflammasome activation in IL-6 primed innate immune cells is regulated by baricitinib

OBJECTIVES

Gout is an inflammatory arthropathy caused by the deposition of monosodium urate (MSU). The synthesis and release of IL-1β is crucial for MSU-induced synovial inflammation. The aim of the present study was to investigate the mechanism of MSU crystal-induced autoinflammatory processes.

METHODS

In vitro studies were used to evaluate the role of IL-6 in inflammasome activation in human neutrophils cultured with MSU crystals. Human neutrophils were stimulated with MSU in the presence or absence of IL-6 priming to determine NLRP3 inflammasome activation and subsequent cleaved caspase-1 induction or IL-1β production.

RESULTS

IL-6 or MSU stimulation alone did not result in the efficient IL-1β production from human neutrophils. However, MSU stimulation induced marked IL-1β production from IL-6-primed neutrophils. Pretreatment with baricitinib, which blocks IL-6 receptor signaling, prevented MSU-induced cleaved caspase-1 or IL-1β induction in IL-6-primed neutrophils. Tocilizumab pretreatment also inhibited MSU-mediated IL-1β production from IL-6-primed neutrophils.

CONCLUSION

Priming of human neutrophils with IL-6 promotes uric acid-mediated IL-1β secretion in the absence of microbial stimulation. These results suggest that an endogenous cytokine, IL-6, is involved in MSU-mediated NLRP3 inflammasome activation and subsequent IL-1β production from innate immune cells and has a crucial role in MSU crystal-induced synovial inflammation. These findings provide insights into uric acid-mediated autoinflammation in the innate immune system.

A comparative study on anti-inflammatory drug combinations in domestic pigeons with experimentally induced acute arthritis

The study compares the effect of one-time administration of nonsteroidal and/or steroidal anti-inflammatory combinations by topical or intramuscular (IM) routes to pigeons with monosodium urate (MSU)-induced arthritis. Forty-five adult domestic pigeons were assigned into nine equal groups: NC, negative control; PC, positive control with arthritis; sham, sham control; T1, meloxicam + hydrocortisone; T2, dexamethasone + piroxicam; T3, meloxicam + dexamethasone; T4, hydrocortisone + piroxicam; T5, dexamethasone + hydrocortisone; T6, meloxicam + piroxicam. Arthritis was also induced in T1 to T6 birds. Meloxicam and dexamethasone were administered by IM injection and the other drugs topically right after the induction of arthritis. Different drug combinations significantly decreased one-leg standing time. Induction of arthritis significantly increased TNF-α and IL-6 levels in synovial fluid and serum corticosterone and epinephrine in the PC group. Administration of drugs to birds of Groups T1 and T5 did not significantly change corticosterone concentration, while all different drug combinations decreased epinephrine level. Drug combinations that demonstrated better analgesic effect more strongly reduced serum epinephrine concentration. Meloxicam + hydrocortisone was the most effective combination in reducing inflammatory cytokines. In conclusion, one-time combination therapy with anti-inflammatory agents was effective in the acute management of inflammatory pain due to MSU-induced arthritis in pigeons, even by the topical route.

Interaction of the p.Q141K Variant of the ABCG2 Gene with Clinical Data and Cytokine Levels in Primary Hyperuricemia and Gout

Gout is an inflammatory arthritis influenced by environmental risk factors and genetic variants. The common dysfunctional p.Q141K allele of the ABCG2 gene affects gout development. We sought after the possible association between the p.Q141K variant and gout risk factors, biochemical, and clinical determinants in hyperuricemic, gouty, and acute gouty arthritis cohorts. Further, we studied the correlation of p.Q141K allele and levels of pro-/anti-inflammatory cytokines. Coding regions of the ABCG2 gene were analyzed in 70 primary hyperuricemic, 182 gout patients, and 132 normouricemic individuals. Their genotypes were compared with demographic and clinical parameters. Plasma levels of 27 cytokines were determined using a human multiplex cytokine assay. The p.Q141K variant was observed in younger hyperuricemic/gout individuals (p = 0.0003), which was associated with earlier disease onset (p = 0.004), trend toward lower BMI (p = 0.056), and C-reactive protein (CRP, p = 0.007) but a higher glomerular filtration rate (GFR, p = 0.035). Levels of 19 cytokines were higher, mainly in patients with acute gouty arthritis (p < 0.001), irrespective of the presence of the p.Q141K variant. The p.Q141K variant influences the age of onset of primary hyperuricemia or gout and other disease-linked risk factors and symptoms. There was no association with cytokine levels in the circulation.

Phytochemicals as Novel Therapeutic Strategies for NLRP3 Inflammasome-Related Neurological, Metabolic, and Inflammatory Diseases

Several lines of evidence point out the relevance of nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome as a pivotal player in the pathophysiology of several neurological and psychiatric diseases (i.e., Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS), amyotrophic lateral sclerosis, and major depressive disorder), metabolic disorders (i.e., obesity and type 2 diabetes) and chronic inflammatory diseases (i.e., intestinal inflammation, arthritis, and gout). Intensive research efforts are being made to achieve an integrated view about the pathophysiological role of NLRP3 inflammasome pathways in such disorders. Evidence is also emerging that the pharmacological modulation of NLRP3 inflammasome by phytochemicals could represent a promising molecular target for the therapeutic management of neurological, psychiatric, metabolic, and inflammatory diseases. The present review article has been intended to provide an integrated and critical overview of the available clinical and experimental evidence about the role of NLRP3 inflammasome in the pathophysiology of neurological, psychiatric, metabolic, and inflammatory diseases, including PD, AD, MS, depression, obesity, type 2 diabetes, arthritis, and intestinal inflammation. Special attention has been paid to highlight and critically discuss current scientific evidence on the effects of phytochemicals on NLRP3 inflammasome pathways and their potential in counteracting central neuroinflammation, metabolic alterations, and immune/inflammatory responses in such diseases.

Pharmacological basis for use of madecassoside in gouty arthritis: anti-inflammatory, anti-hyperuricemic, and NLRP3 inhibition

Objectives: Gouty arthritis is caused by the deposition of monosodium urate (MSU) crystals in joints, which is associated with the rise of serum urate content. This study aims to investigate the therapeutic effect of Madecassoside on gouty arthritis and hyperuricemia. Methods: DBA/1 mice were intradermally injected with MSU to stimulate joint inflammation or intraperitoneally injected with MSU to trigger peritonitis. Moreover, ICR mice were exposed to potassium oxonate to stimulate hyperuricemia. Results: Madecassoside repressed MSU-triggered pad swelling, joint 99mTc uptake, and joint inflammation in DBA/1 mice with gouty arthritis. Neutrophil infiltration and IL-1β & IL-6 & MCP-1 secretion was also alleviated in lavage fluids from DBA/1 mice with peritonitis due to Madecassoside treatment. Furthermore, Madecassoside decreased MSU-induced neutrophil cytosolic factor 1, caspase-1 and NLRP3 expression in mice with peritoneal inflammation. In hyperuricemic mice, Madecassoside improved renal dysfunction. Serum uric acid, BUN, and creatinine were down-regulated by Madecassoside. Conclusion: These findings indicate that Madecassoside has potential to ameliorate inflammation in both acute gouty arthritis model and peritonitis model, probably via regulating IL-1β and NLRP3 expression. Practical point: Madecassoside also exhibited a urate-lowering effect and a renal protective effect in hyperuricemic mice.

Metabolic disturbances in synovial fluid are involved in the onset of synovitis in heifers with acute ruminal acidosis

Acute ruminal acidosis (ARA) is the result of increased intake of highly fermentable carbohydrates, which frequently occurs in dairy cattle and is associated with aseptic polysynovitis. To characterise the metabolic changes in the joints of animals with ARA, we performed an untargeted gas chromatography-mass spectrometry (GC-MS)-based metabolomic analysis of synovial fluid. Seven heifers were challenged with an intraruminal oligofructose overload (13 g/kg of body weight [BW]) dissolved in water. Synovial fluid samples were collected at 0, 9 and 24 h post-overload. Metabolome analysis revealed the presence of 67 metabolites. At 9 h post-overload, glyceric acid, cellobiose, fructose and lactic acid were all increased, whereas at 24 h, sorbitol, lactic acid and fructose levels were all increased >10-fold. At 24 h, citric acid and threonine levels were significantly reduced. We detected increased L- and D-lactate, and the presence of interleukin-6 (IL-6) in synovial fluid. Furthermore, using bovine fibroblast-like synoviocytes, we observed that D-lactate induces IL-6 synthesis. Our results suggest that ARA produces severe metabolomic changes in synovial fluid, including disturbances in starch and sucrose metabolism, and increased lactate levels. These changes were observed prior to the appearance of synovitis, suggesting a potential role in the onset of polysynovitis.

[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.

Lower vitamin D levels are associated with depression in patients with gout

BACKGROUND

Depression is commonly observed among patients with gout. Low levels of vitamin D have been associated with depression in non-gout subjects. We examined the association of vitamin D levels with depression in patients with gout.

METHODS

We conducted a cross-sectional study of 186 gout patients at the Endocrinology Department of First Affiliated Hospital of Jiaxing University. Levels of serum 25-hydroxyvi-tamin D (25(OH)D) were determined using a competitive protein-binding assay. The 17-item Hamilton Depression Scale was used for screening for depressive symptoms. Diagnosis of depression in gout patients was made in accordance with Diagnostic and Statistical Manual of Mental Disorders, fifth edition criteria for depression. Multivariate analysis was performed using logistic regression models.

RESULTS

Thirty-two gout patients (17.2%) were diagnosed as having depression. Patients with depression showed significantly lower 25(OH)D levels as compared to patients without depression (46.4±19.0 vs 57.0±17.3 nmol/L, P<0.001). Significant differences in 25(OH)D quartiles of gout patients were observed between the patients with depression and the patients without depression (P=0.003). In multivariate analyses, serum 25(OH)D levels (≤40.0 nmol/L) were independently associated with depression in patients with gout (OR 3.833, 95% CI 1.406-10.453, P=0.009).

CONCLUSION

Our study demonstrates an important association between serum vitamin D levels and depression in patients with gout.

Goals of gout treatment: a patient perspective

To assess the goals of gout treatment from a patient perspective, a convenience sample of consecutive patients with doctor-diagnosed gout seen at a community-based outpatient clinic were invited. Sex-stratified nominal groups were conducted until saturation was achieved. Responses were collected verbatim, discussed, and rank-ordered by each participant. Thirty-six patients with doctor-diagnosed gout participated in 12 nominal groups: 6 male only, 5 female only, and 1 group with both. Mean age was 61.9 years (SD, 12.3); mean gout duration was 13.3 years (SD, 12.5); 53% were men, 64% African-American, 42% retired, 47% currently married, 87% were using either allopurinol and/or febuxostat, and 40% had had no gout flares in the last 6 months. The top 5 treatment goals accounted for 91% of all votes and included the following: (1) prevent and better manage flare-ups and improve function (25%), (2) eliminate flare-ups/disease remission (30%), (3) diet and activity modification/lifestyle change (13%), (4) patient education and public awareness (12%), and (5) medication management and minimization of side effects (11%). When examining the top-rated concern for each nominal group, the first two goals were nominated by four groups each, diet/activity modification and medication management by 1 group each, and patient education by 3 groups. There were no differences evident by sex in top-ranked treatment goal. People with gout identified and rank-ordered treatment goals relevant to them. Providers of gout care need to be cognizant of these goals. Disease management concordant with these treatment goals might lead to a more satisfied, informed patient.