The inflammatory process of gout and its treatment

Comparison of Gout Flares With the Initiation of Treat-to-Target Allopurinol and Febuxostat: A Post-Hoc Analysis of a Randomized Multicenter Trial

OBJECTIVE

Initiating urate-lowering therapy (ULT) in gout can precipitate arthritis flares. There have been limited comparisons of flare risk during the initiation and escalation of allopurinol and febuxostat, administered as a treat-to-target strategy with optimal anti-inflammatory prophylaxis.

METHODS

This was a post-hoc analysis of a 72-week randomized, double-blind, placebo-controlled, noninferiority trial comparing the efficacy of allopurinol and febuxostat. For this analysis, the occurrence of flares was examined during weeks 0 to 24 when ULT was initiated and titrated to a serum urate (sUA) goal of less than 6 mg/dl (<5 mg/dl if tophi). Flares were assessed at regular intervals through structured participant interviews. Predictors of flare, including treatment assignment, were examined using multivariable Cox proportional hazards regression.

RESULTS

Study participants (n = 940) were predominantly male (98.4%) and had a mean age of 62.1 years with approximately equal proportions receiving allopurinol or febuxostat. Mean baseline sUA was 8.5 mg/dl and all participants received anti-inflammatory prophylaxis (90% colchicine). In a multivariable model, there were no significant associations of ULT treatment (hazard ratio [HR] 1.17; febuxostat vs allopurinol), ULT-dose escalation (HR 1.18 vs no escalation), prophylaxis type, or individual comorbidity with flare and no evidence of ULT-dose escalation interaction. Factors independently associated with flare risk during ULT initiation/escalation included younger age, higher baseline sUA, and absence of tophi.

CONCLUSION

These results demonstrate that gout flare risk during the initiation and titration of allopurinol is similar to febuxostat when these agents are administered according to a treat-to-target strategy using gradual ULT-dose titration and best practice gout flare prophylaxis.

Ameliorative impacts of Sinapic acid against monosodium urate crystal-induced gouty arthritis and inflammation through different signaling pathways

As known, gout a metabolic disease due to the urate crystals deposition in the joints and affect human health and state. Humans are looking for safe natural remedies from plants with safe, low cost and high effect on their health. Sinapic acid (SA) is found in plants and used as phytoconstituent in human diets. SA has strong antioxidant activity, bone-regenerative, anti-cancer, anti-allergic, and antidiabetic effects. The current study was outlined to confirm the anti-gout potential of SA against monosodium urate crystals (MSU)-induced gouty arthritis in mice. Positive gouty arthritis was conducted by administration of colchicine and MSU in the hind paw. SA was orally administered to negative and positive MSU arthritic mice at 25 and 50 mg/kg, one-hour before MSU injection (100 μg/kg intra-articular). At the end of the experiment, sampling was done for serum, histopathology, oxidative stress and gene expression analysis. The results showed that SA significantly recovered the joint edema and recovered MSU crystals-showed histopathological changes. The production of cytokines, leukocyte recruitment, oxidative stress, and nucleotide-binding domain, leucinerich-containing family, pyrin domain-containing-3 (NLRP3)-inflammasome genes expressions were increased in positive arthritic mice and ameliorated significantly by SA administration. Moreover, SA showed ameliorative impacts on air pouch model of mice as reported by the down regulation in the expression of inflammation related blood cells, proinflammatory cytokines and other transcriptional genes. In conclusion, sinapic acid showed a potential therapeutic use against side effects accompanying gouty arthritis and is good as a supplement against inflammation associated disorders.

Fangyukangsuan granules ameliorate hyperuricemia and modulate gut microbiota in rats

Hyperuricaemia (HUA) is a metabolic disorder characterised by high blood uric acid (UA) levels; moreover, HUA severity is closely related to the gut microbiota. HUA is also a risk factor for renal damage, diabetes, hypertension, and dyslipidaemia; however, current treatments are associated with detrimental side effects. Alternatively, Fangyukangsuan granules are a natural product with UA-reducing properties. To examine their efficacy in HUA, the binding of small molecules in Fangyukangsuan granules to xanthine oxidase (XOD), a key factor in UA metabolism, was investigated via molecular simulation, and the effects of oral Fangyukangsuan granule administration on serum biochemical indices and intestinal microorganisms in HUA-model rats were examined. Overall, 24 small molecules in Fangyukangsuan granules could bind to XOD. Serum UA, creatinine, blood urea nitrogen, and XOD levels were decreased in rats treated with Fangyukangsuan granules compared to those in untreated HUA-model rats. Moreover, Fangyukangsuan granules restored the intestinal microbial structure in HUA-model rats. Functional analysis of the gut microbiota revealed decreased amino acid biosynthesis and increased fermentation of pyruvate into short-chain fatty acids in Fangyukangsuan granule-treated rats. Together, these findings demonstrate that Fangyukangsuan granules have anti-hyperuricaemic and regulatory effects on the gut microbiota and may be a therapeutic candidate for HUA.

Investigation of the mechanism of action of chemical constituents of celery seed against gout disease using network pharmacology, molecular docking, and molecular dynamics simulations

Celery (Apium graveolens L.) has long been considered as a potential herbal medicine for the prevention and treatment of gout. However, the relationship between the chemical constituents and pharmacological activities of this medicinal plant has not been fully investigated yet. Therefore, this study aims to apply network pharmacology, molecular docking and molecular dynamics to explore the relationship between the chemical constituents of celery seed and its biological effects in the treatment of gout. Network pharmacology was built and analyzed based on the data collected from GeneCards, OMIM databases and SwissTargetPrediction web server using Cytoscape 3.9.0 software. The GO and KEGG pathway analysis of the potential targets of celery seed related to gout disease was performed using the ShinyGO v0.75 app. Molecular docking and molecular dynamics were carried out using Autodock vina and NAMD 2.14 software, respectively. The network analysis identified 16 active compounds and thirteen key targets of celery seed in the treatment of gout. The GO analysis and the KEGG pathway enrichment analysis suggested that the mechanism of action of the chemical constituents of celery seed might be involved in several pathways, notably the PI3K-Akt signaling pathway, Ras signaling pathway, and HIF-1 signaling pathway, respectively. Molecular docking and molecular dynamics revealed that apiumetin might be an important chemical that plays a key role in the pharmacological effect of celery seed. These results might be useful to select the Q-markers to control the quality of the products from celery seeds.Communicated by Ramaswamy H. Sarma.

Targeting Neutrophil Extracellular Traps in Gouty Arthritis: Insights into Pathogenesis and Therapeutic Potential

Gouty arthritis (GA) is an immune-mediated disorder characterized by severe inflammation due to the deposition of monosodium urate (MSU) crystals in the joints. The pathophysiological mechanisms of GA are not yet fully understood, and therefore, the identification of effective therapeutic targets is of paramount importance. Neutrophil extracellular traps (NETs), an intricate structure of DNA scaffold, encompassing myeloperoxidase, histones, and elastases - have gained significant attention as a prospective therapeutic target for gouty arthritis, due to their innate antimicrobial and immunomodulatory properties. Hence, exploring the therapeutic potential of NETs in gouty arthritis remains an enticing avenue for further investigation. During the process of gouty arthritis, the formation of NETs triggers the release of inflammatory cytokines, thereby contributing to the inflammatory response, while MSU crystals and cytokines are sequestered and degraded by the aggregation of NETs. Here, we provide a concise summary of the inflammatory processes underlying the initiation and resolution of gouty arthritis mediated by NETs. Furthermore, this review presents an overview of the current pharmacological approaches for treating gouty arthritis and summarizes the potential of natural and synthetic product-based inhibitors that target NET formation as novel therapeutic options, alongside elucidating the intrinsic challenges of these inhibitors in NETs research. Lastly, the limitations of HL-60 cell as a suitable substitute of neutrophils in NETs research are summarized and discussed. Series of recommendations are provided, strategically oriented towards guiding future investigations to effectively address these concerns. These findings will contribute to an enhanced comprehension of the interplay between NETs and GA, facilitating the proposition of innovative therapeutic strategies and novel approaches for the management of GA.

Association between patient adherence and treat-to-target in gout: A cross-sectional study

The implementation of a treat-to-target (T2T) approach has been widely recommended for achieving optimal outcomes in gout treatment, as substantiated by a wealth of compelling evidence. However, a paucity of knowledge exists regarding the barriers hindering effective T2T management in China. This study seeks to investigate the factors contributing to treatment failure within the context of the T2T strategy. A cross-sectional, multi-center investigation was conducted, involving the completion of electronic questionnaires by outpatients undergoing urate-lowering treatment for a duration exceeding 6 months. These questionnaires encompassed demographic information, disease-related conditions, comorbid conditions, and management. The study analyzed factors associated with serum uric acid levels exceeding 360 µmol/L, poor disease control, and poor medication adherence. A total of 425 valid questionnaires were collected, representing 90.8% of the patients. The T2T implementation rate was 26.82% (n = 114). Factors linked to serum uric acid levels surpassing 360 µmol/L included moderate medication adherence (odds ratio (OR) = 2.35; 95% confidence interval (CI) 1.17-4.77; P = .016), poor medication adherence (OR = 4.63; 95% CI 2.28-9.51; P < .001), and management by general practitioners (OR = 0.60; 95% CI 0.37-0.97; P = .036). The rate of well-controlled patients was 14.35% (n = 61). Predictors of not well controlled encompassed the presence of tophi (OR = 2.48; 95% CI 1.17-5.61; P = .023), general medication adherence (OR = 2.78; 95% CI 1.28-6.05; P = .009), poor medication adherence (OR = 6.23; 95% CI 2.68-14.77; P < .001), and poor patient's perception of gout (OR = 4.07; 95% CI 1.41-13.91; P = .015). A poor medication adherence rate of 55.29% (n = 235) was observed, with lower rates of poor medication adherence associated with the use of febuxostat (OR = 0.35; 95% CI 0.14-0.83; P = .02), uric acid levels exceeding 360 µmol/L (OR = 3.05; 95% CI 1.84-5.12; P = .00), moderate patient education (OR = 2.28; 95% CI 1.29-4.15; P = .01), moderate diet control (OR = 1.98; 95% CI 1.17-3.41; P = .01), and poor diet control (OR = 3.73; 95% CI 1.26-12.83; P = .02). The rate of T2T implementation in China is notably low among patients undergoing urate-lowering treatment of gout beyond 6 months. Importantly, medication adherence demonstrates a significant association with T2T outcomes.

Comparative studies of xanthine oxidase inhibitors viz. allopurinol and febuxostat against induced hyperuricaemia in a poultry model

In this study, an attempt was made to evaluate the relative efficacy of two important anti-gout agents, viz. allopurinol and febuxostat, in the control of hyperuricaemia/gout using a poultry model. A 21-day study was conducted on 48 Vencobb-400 broiler chicks randomly divided into four groups. In one group hyperuricaemia/gout was induced by the oral administration of diclofenac (group D); in two other groups the ameliorative effect of the two drugs under study was investigated by providing both simultaneously, i.e. diclofenac and allopurinol (group DA), diclofenac and febuxostat (group DF); and the fourth group was kept un-induced and untreated as a control (group C). Both allopurinol and febuxostat inhibit xanthine oxidase enzymes, thereby reducing the production of uric acid. The birds kept on diclofenac alone exhibited the highest level of hyperuricaemia, clinical signs of gout, and overt adverse changes in the visceral organs, whereas these changes were lesser in allopurinol- and febuxostat-treated groups. Furthermore, haematological, biochemical, patho-morphological, and ultra-structural studies using transmission electron microscopy were carried out to evaluate the pathology and, thus, the ameliorative effect of allopurinol and febuxostat. The findings proved that allopurinol and febuxostat carry definite ameliorative potential as anti-hyperuricemic and anti-gout agents in poultry, which was better expressed by febuxostat compared to allopurinol.

Modified Simiaowan prevents and treats gouty arthritis via the Nrf2/NLRP3 inflammasome signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Modified Simiaowan (MSM) is a six-herb formula that has been shown to be effective in gouty arthritis (GA) has been proven, but its regulatory mechanism has not been fully elucidated.

AIM OF THE STUDY

To investigate the therapeutic effects and mechanism of MSM on gouty arthritis.

MATERIALS AND METHODS

Mouse J774A.1 macrophages were induced with Lipopolysaccharide (LPS) and then stimulated with Adenosine 5'-triphosphate (ATP) or Nigericin (Nig.) in presence or absence of MSM. Expression of key indicators of pro-inflammatory cytokines and the NLRP3 inflammasome signaling pathway were investigated by western blot, ELISA and qRT-PCR. Fluorescence staining and flow cytometry were performed to detect intracellular reactive oxygen species (ROS) production. Another study, the anti-inflammatory and antioxidant activities of MSM were evaluated in rats with monosodium urate (MSU) -induced gouty arthritis using ELISA, hematoxylin-eosin staining (HE) staining, immunohistochemistry, and oxidative stress kits to measure relevant inflammatory markers and oxidative stress-related biomarkers.

RESULTS

ELISA and qRT-PCR results demonstrated that MSM effectively reduced the secretion and the mRNA expression levels of pro-inflammatory cytokines. Western blot results indicated that MSM can suppress the expression of NLRP3, an inflamasomes-related protein. In addition, MSM regulated the transition from M1 to M2 macrophages and upregulated the protein expression of Nrf2 and HO-1. The flow cytometry results and the fluorescence staining result were consistent with hypothesis that a large amount of ROS could be effectively cleared by MSM. However, the anti-inflammatory effect of MSM was attenuated after the use of ML385. In vivo experiments demonstrated that joint swelling was significantly attenuated and knee neutrophil infiltration was alleviated in rats given MSM. SOD and GSH-px levels were elevated significantly, while COX-2 and MDA levels decreased. The immunohistochemical results suggested that MSM could effectively inhibit the activation of the NLRP3 inflammasome and the regulation of macrophage polarization in rat synovial tissue, and remarkably enhance the expression of Nrf2 and HO-1.

CONCLUSION

MSM has potent anti-inflammatory and antioxidant effects on MSU-induced gouty arthritis. MSM alleviates GA through Nrf2/HO-1/ROS/NLRP3 signaling pathway.

Unsupervised cluster analysis of clinical and ultrasound features reveals unique gout subtypes: Results from the Egyptian College of Rheumatology (ECR)

BACKGROUND

Gout comprises a heterogeneous group of disorders; however, comorbidities have been the focus of most efforts to classify disease subgroups.

OBJECTIVES

We applied cluster analysis using musculoskeletal ultrasound (MSUS) combined with clinical and laboratory findings in patients with gout to identify disease phenotypes, and differences across clusters were investigated.

PATIENTS AND METHODS

Patients with gout who complied with the ACR/EULAR classification criteria were enrolled in the Egyptian College of Rheumatology (ECR)-MSUS Study Group, a multicenter study. Selected variables included demographic, clinical, and laboratory findings. MSUS scans assessed the bilateral knee and first metatarsophalangeal joints. We performed a K-mean cluster analysis and compared the features of each cluster.

RESULTS

425 patients, 267 (62.8 %) males, mean age 54.2 ± 10.3 years were included. Three distinct clusters were identified. Cluster 1 (n = 138, 32.5 %) has the lowest burden of the disease and a lower frequency of MSUS characteristics than the other clusters. Cluster 2 (n = 140, 32.9 %) was mostly women, with a low rate of urate-lowering treatment (ULT). Cluster 3 (n = 147, 34.6 %) has the highest disease burden and the greatest proportion of comorbidities. Significant MSUS variations were found between clusters 2 and 3: joint effusion (p < 0.0001; highest: cluster 3), power Doppler signal (p < 0.0001; highest: clusters 2), and aggregates of crystal deposition (p < 0.0001; highest: cluster 3).

CONCLUSION

Cluster analysis using MSUS findings identified three gout subgroups. People with more MSUS features were more likely to receive ULT. Treatment should be tailored according to the cluster and MSUS features.

The dysregulation of immune cells induced by uric acid: mechanisms of inflammation associated with hyperuricemia and its complications

Changes in lifestyle induce an increase in patients with hyperuricemia (HUA), leading to gout, gouty arthritis, renal damage, and cardiovascular injury. There is a strong inflammatory response in the process of HUA, while dysregulation of immune cells, including monocytes, macrophages, and T cells, plays a crucial role in the inflammatory response. Recent studies have indicated that urate has a direct impact on immune cell populations, changes in cytokine expression, modifications in chemotaxis and differentiation, and the provocation of immune cells by intrinsic cells to cause the aforementioned conditions. Here we conducted a detailed review of the relationship among uric acid, immune response, and inflammatory status in hyperuricemia and its complications, providing new therapeutic targets and strategies.

Anti-inflammation is an important way that Qingre-Huazhuo-Jiangsuan recipe treats acute gouty arthritis

Background: Acute gouty arthritis (AGA) significantly impairs patients' quality of life. Currently, existing therapeutic agents exhibit definite efficacy but also lead to serious adverse reactions. Therefore, it is essential to develop highly efficient therapeutic agents with minimal adverse reactions, especially within traditional Chinese medicine (TCM). Additionally, food polyphenols have shown potential in treating various inflammatory diseases. The Qingre-Huazhuo-Jiangsuan-Recipe (QHJR), a modification of Si-Miao-San (SMS), has emerged as a TCM remedy for AGA with no reported side effects. Recent research has also highlighted a strong genetic link to gout. Methods: The TCM System Pharmacology (TCMSP) database was used to collect the main chemical components of QHJR and AGA-related targets for predicting the metabolites in QHJR. HPLC-Q-Orbitrap-MS was employed to identify the ingredients of QHJR. The collected metabolites were then used to construct a Drugs-Targets Network in Cytoscape software, ranked based on their "Degree" of significance. Differentially expressed genes (DEGs) were screened in the Gene Expression Omnibus (GEO) database using GEO2R online analysis. Subsequently, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed. The DEGs were utilized to construct a Protein-Protein Interaction (PPI) Network via the STRING database. In vivo experimental validation was conducted using colchicine, QHJR, rapamycin (RAPA), and 3-methyladenine (3-MA) as controls to observe QHJR's efficacy in AGA. Synovial tissues from rats were collected, and qRT-PCR and Western blot assays were employed to investigate Ampk-related factors (Ampk, mTOR, ULK1), autophagy-related factors (Atg5, Atg7, LC3, p62), and inflammatory-related factors (NLRP3). ELISA assays were performed to measure inflammatory-related factor levels (IL-6, IL-1β, TNF-α), and H&E staining was used to examine tissue histology. Results: Network analysis screened out a total of 94 metabolites in QHJR for AGA. HPLC-Q-Orbitrap-MS analysis identified 27 of these metabolites. Notably, five metabolites (Neochlorogenic acid, Caffeic acid, Berberine, Isoliquiritigenin, Formononetin) were not associated with any individual herbal component of QHJR in TCMSP database, while six metabolites (quercetin, luteolin, formononetin, naringenin, taxifolin, diosgenin) overlapped with the predicted results from the previous network analysis. Further network analysis highlighted key components, such as Caffeic acid, cis-resveratrol, Apigenin, and Isoliquiritigenin. Other studies have found that their treatment of AGA is achieved through reducing inflammation, consistent with this study, laying the foundation for the mechanism study of QHJR against AGA. PPI analysis identified TNF, IL-6, and IL-1β as hub genes. GO and KEGG analyses indicated that anti-inflammation was a key mechanism in AGA treatment. All methods demonstrated that inflammatory expression increased in the Model group but was reversed by QHJR. Additionally, autophagy-related expression increased following QHJR treatment. The study suggested that AMPKα and p-AMPKα1 proteins were insensitive to 3 MA and RAPA, implying that AMPK may not activate autophagy directly but through ULK1 and mTOR. Conclusion: In conclusion, this study confirms the effectiveness of QHJR, a modified formulation of SMS (a classic traditional Chinese medicine prescription for treating gout), against AGA. QHJR, as a TCM formula, offers advantages such as minimal safety concerns and potential long-term use. The study suggests that the mechanism by which QHJR treats AGA may involve the activation of the AMPK/mTOR/ULK1 pathway, thereby regulating autophagy levels, reducing inflammation, and alleviating AGA. These findings provide new therapeutic approaches and ideas for the clinical treatment of AGA.

The inflammation process of gout arthritis and its treatment

Gout arthritis is an inflammatory condition that occurs suddenly in joints affected by high uric acid levels (hyperuricemia). The uric acid levels in this disease fluctuate throughout its various phases, resulting in frequent or recurrent attacks. This study aims to review some aspects of gout arthritis, such as its pathophysiology, treatment goals, and adverse drug reactions. This study employs review literature using articles published between 2017 and 2022 as the research methodology. Furthermore, articles under 2017 are used as references if they are relevant to the study's subject matter. The findings showed the importance of the pathogenesis of inflammation in the treatment of gout arthritis. It is also recommended to use anti-inflammatories such as colchicine and uric acid-lowering medications starting at a specific time to prevent unintended risks. Hence, pharmacotherapy management's adverse effects include nausea, vomiting, myalgia, neuropathy, and stomach pain.

Ouratea spectabilis and its Biflavanone Ouratein D Exert Potent Anti-inflammatory Activity in MSU Crystal-induced Gout in Mice

Gouty arthritis (GA) is an inflammatory arthritis triggered by the deposition of monosodium urate monohydrate (MSU) crystals, causing pain, inflammation, and joint damage. Several drugs are currently employed to manage acute flares of GA, but they either have limited effectiveness or induce severe adverse reactions. Ouratea spectabilis is traditionally used in Brazil to treat gastric ulcers and rheumatism. The ethanolic extract of O. spectabilis stems (OSpC) and four biflavanones (ouratein A - D) isolated thereof were evaluated in a murine model of GA induced by the injection of MSU crystals. The underlying mechanism of action of ouratein D was investigated in vitro in cell cultures by measurement of IL-1β levels by ELISA and Western blot analysis. The administration of OSpC (10, 30 or 100 mg/Kg, p. o.) reduced the migration of total inflammatory cells, monocytes, and neutrophils and diminished the levels of IL-1β and CXCL1 in the synovial tissue. Among the tested compounds, only ouratein D (1 mg/Kg) reduced the migration of the inflammatory cells and it was shown to be active up to 0.01 mg/Kg (equivalent to 0.34 nM/Kg, p. o.). Treatment of pre-stimulated THP-1 cells (differentiated into macrophages) or BMDMs with ouratein D reduced the release of IL-1β in both macrophage lines. This biflavanone reduced the activation of caspase-1 (showed by the increase in the cleaved form) in supernatants of cultured BMDMs, evidencing its action in modulating the inflammasome pathway. The obtained results demonstrate the anti-gout properties of O. spectabilis and point out ouratein D as the bioactive component of the assayed extract.

Gouty arthritis involves impairment of autophagic degradation via cathepsin D inactivation-mediated lysosomal dysfunction that promotes apoptosis in macrophages

This study examined autophagy-lysosome pathway (ALP) perturbations in synovial monocytes/macrophages from patients with gouty arthritis (GA) and the associations of ALP perturbations with cell death. Synovial fluid mononuclear cells (SFMCs) and synovial tissues (STs) from patients with GA, as well as monosodium urate (MSU) crystal-exposed macrophages, underwent immunoblotting, quantitative polymerase chain reaction, and immunofluorescence analyses of markers linked to the ALP (microtubule-associated protein 1 light chain 3B [LC3B], p62, cathepsin D [CTSD], and lysosome-associated membrane protein 2 [LAMP2]) and cell death (caspase-3). GA STs underwent immunohistochemistry and immunofluorescence analyses to determine the distributions of LC3B-positive autophagosomes and macrophages. GA SFMCs and STs exhibited impaired autophagic degradation, indicated by elevated levels of LC3B and p62, along with CTSD upregulation and caspase-3 activation. Macrophages from GA STs exhibited significant accumulation of LC3B-positive autophagosomes. The temporal effects of MSU crystals on the ALP and the associations of these effects with cell death were investigated using a macrophage model of GA. MSU crystal-exposed macrophages exhibited early (2 h) autophagosome formation but later (6-24 h) autophagic flux impairment, demonstrated by p62 accumulation, lysosomal inhibitor failure to increase LC3B accumulation, and LC3B colocalization with p62. These macrophages exhibited autophagic flux impairment because of CTSD inactivation-mediated lysosomal dysfunction, which caused immature CTSD to accumulate within damaged LAMP2-positive lysosomes. This accumulation coincided with caspase-3-dependent cell death (24 h) that was unaffected by CTSD inhibition. These findings indicate that GA involves MSU crystal-induced impairment of autophagic degradation via CTSD inactivation-mediated lysosomal dysfunction, which promotes apoptosis in macrophages.

Novel method to quantify peptidylarginine deiminase activity shows distinct citrullination patterns in rheumatoid and juvenile idiopathic arthritis

Introduction

Peptidylarginine deiminases (PADs) mediate citrullination, an irreversible posttranslational modification that converts arginine to citrulline residues in proteins. Rheumatoid arthritis (RA) is characterized by unique autoantibodies that recognize citrullinated peptides, which are highly specific for this disease. However, the mechanism preceding the anti-citrulline response remains largely unclear. PAD enzymes are known to fuel the autoimmune response by generating autoreactive epitopes, and sustain local synovial inflammation through neutrophil extracellular trap formation. Therefore, detecting endogenous PAD activity is important to understand the pathogenesis of arthritis.

Methods

In this study, we improved a fluorescent in vitro assay to enable endogenous PAD activity characterization in complex samples. We combine the use of an in-house synthetic, arginine-rich substrate and a negatively charged dye molecule to visualize enzyme activity.

Results

This pioneering PAD assay allowed profiling of active citrullination in leukocytes and in local and systemic samples of an arthritis cohort. Our results reveal that RA and juvenile idiopathic arthritis (JIA) synovial fluids display similar levels of PAD activity. In contrast, citrullination was limited in joints of patients suffering from gout or Lyme's disease. Interestingly, in blood, a higher level of extracellular citrullination was only found in anti-CCP-positive RA patients.

Discussion

Our finding suggests that enhanced synovial PAD activity drives the loss in tolerance towards citrullinated proteins and that systemic citrullination may indicate the risk for developing citrulline-specific autoimmunity.

Anethole ameliorates inflammation induced by monosodium urate in an acute gouty arthritis model via inhibiting TLRs/MyD88 pathway

OBJECTIVE

To assess the effects of anethole on monosodium urate (MSU)-induced inflammatory response, investigate its role in acute gouty arthritis (AGA), and verify its molecular mechanism.

METHODS

Hematoxylin and eosin staining assay and time-dependent detection of degree of ankle swelling were performed to assess the effects of anethole on joint injury in MSU-induced AGA mice. Enzyme-linked-immunosorbent serologic assay was performed to demonstrate the production levels of inflammatory factors (interleukin 1β [IL-1β], interleukin 6 [IL-6], interleukin 8 [IL-8], tumor necrosis factor α [TNF-α], and monocyte chemo-attractant protein-1 [MCP-1]) in MSU-induced AGA mice. Western blot assays were used to confirm the effects of anethole on oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activity and the activation of toll-like receptors (TLRs)-myeloid differentiation factor 88 (MyD88) pathway in MSU-induced AGA mice.

RESULTS

We observed that a significant joint injury occurred in MSU-induced AGA mice. Anethole could alleviate the pathological injury of the synovium in MSU-induced AGA mice and suppressed ankle swelling. In addition, we observed that anethole could inhibit MSU-induced inflammatory response and inflammasome activation in MSU-induced AGA mice. Moreover, we discovered that anethole enabled to inhibit the activation of TLRs/MyD88 pathway in MSU-induced AGA mice. Our findings further confirmed that anethole contributed to the inhibitory effects on progression in MSU-induced AGA mice.

CONCLUSION

It confirmed that anethole ameliorated the MSU-induced inflammatory response in AGA mice in vivo via inhibiting TLRs-MyD88 pathway.

Medicinal fungus Phellinus igniarius alleviates gout in vitro by modulating TLR4/NF-kB/NLRP3 signaling

Background:Phellinus igniarius (P. igniarius) is a valuable medicinal and edible fungus with various biological activities such as anti-inflammation, antioxidation, and immune regulation. In this study, we explored the effects of P. igniarius on a gout model in vitro.

Methods: The DPPH, ABTS, and FRAP methods were combined to determine and compare the antioxidant activities of wild P. igniarius total polyphenols (WPP) and cultivated P. igniarius total polyphenols (CPP) in vitro. Spectrophotometry was used to compare the inhibitory effect of WPP and CPP on xanthine oxidase (XO) activity to evaluate anti-hyperuricemia activity in vitro. HUVECs were stimulated with monosodium urate (MSU) crystals for 24 h to establish an acute gouty inflammation model in vitro. The protective effects were compared by measuring cell viability; the contents of ICAM-1, IL-1β, IL-6 and VCAM-1; the protein expressions of TLR4 and NLRP3; reactive oxygen species production; and the nuclear translocation of NF-κB p65. UHPLC-QE-MS technology was used to explore the potential metabolic mechanism of P. igniarius against gout.

Results: WPP and CPP had strong antioxidant capacity, and the antioxidant capacity of CPP was similar to that of WPP. In a comparative experiment of xanthine oxidase activity inhibition by WPP and CPP, the IC₅₀ values were 88.19 μg/ml and 108.0 μg/ml, respectively. At a dose of 40 μg/ml, WPP and CPP significantly improved the decrease in cell viability induced by monosodium urate (150 μg/ml) and inhibited the increase in inflammatory factors such as ICAM-1, IL-1β, IL-6, and VCAM-1. The increase in TLR4 and NLRP3 protein expression induced by MSU crystals in HUVECs was also significantly inhibited by total polyphenols from wild and cultivated P. igniarius. In addition, both significantly improved MSU-induced ROS overproduction and NF-κB p65 nuclear translocation. WPP and CPP may primarily be involved in phenylalanine metabolism and lysophosphatidylcholine metabolism in their role in the treatment of gout.

Conclusion: CPP and WPP both showed good antioxidant activity and xanthine oxidase inhibitory activity and had good therapeutic effects on the gout model in vitro. Furthermore, this study indicated that cultivated P. igniarius had a protective effect similar to that of wild P. igniarius, which would be expected to improve the shortage of wild P. igniarius and promote the development of the cultivated P. igniarius industry and product development.

Microbiome-associated human genetic variants impact phenome-wide disease risk

Human genetic variation associates with the composition of the gut microbiome, yet its influence on clinical traits remains largely unknown. We analyzed the consequences of nearly a thousand gut microbiome-associated variants (MAVs) on phenotypes reported in electronic health records from tens of thousands of individuals. We discovered and replicated associations of MAVs with neurological, metabolic, digestive, and circulatory diseases. Five significant MAVs in these categories correlate with the relative abundance of microbes down to the strain level. We also demonstrate that these relationships are independently observed and concordant with microbe by disease associations reported in case-control studies. Moreover, a selective sweep and population differentiation impacted some disease-linked MAVs. Combined, these findings establish triad relationships among the human genome, microbiome, and disease. Consequently, human genetic influences may offer opportunities for precision diagnostics of microbiome-associated diseases but also highlight the relevance of genetic background for microbiome modulation and therapeutics.

The Interaction Between Dietary Fructose and Gut Microbiota in Hyperuricemia and Gout

With the worldwide epidemics of hyperuricemia and associated gout, the diseases with purine metabolic disorders have become a serious threat to human public health. Accumulating evidence has shown that they have been linked to increased consumption of fructose in humans, we hereby made a timely review on the roles of fructose intake and the gut microbiota in regulating purine metabolism, together with the potential mechanisms by which excessive fructose intake contributes to hyperuricemia and gout. To this end, we focus on the understanding of the interaction between a fructose-rich diet and the gut microbiota in hyperuricemia and gout to seek for safe, cheap, and side-effect-free clinical interventions. Furthermore, fructose intake recommendations for hyperuricemia and gout patients, as well as the variety of probiotics and prebiotics with uric acid-lowering effects targeting the intestinal tract are also summarized to provide reference and guidance for the further research.

Efficacy of Xanthine Oxidase Inhibitors in Lowering Serum Uric Acid in Chronic Kidney Disease: A Systematic Review and Meta-Analysis

Objective: Current guidelines for gout recommend a treat-to-target approach with serum uric acid (SUA). However, there is little evidence for the dose-dependent effects of urate-lowering therapy (ULT). Herein, we analyzed the reported SUA-lowering effect and SUA target achievement differences for various doses of xanthine oxidase inhibitors. Methods: Approved ULT drugs were selected from the FDA Drug Database. We included prospective randomized controlled trials of ULT drugs from ClinicalTrials.gov, articles published in the journal “Drugs”, and Embase, a literature database. A meta-analysis was performed to determine the ability of different ULT drugs and doses to lower and maintain a target SUA < 6 mg/dL. Results: We identified 35 trials including 8172 patients with a baseline SUA of 8.92 mg/dL. The allopurinol, febuxostat, and topiroxostat showed dose-proportional SUA-lowering responses. Compared with allopurinol 300 mg daily, febuxostat 80 mg daily and 120 mg daily more effectively maintained SUA < 6 mg/dL. Conclusion: Allopurinol, febuxostat, and topiroxostat showed dose-proportional ability to lower and achieve a target SUA < 6 mg/dL. Significance and Innovations. We showed dose-dependent SUA lowering effects of allopurinol, febuxostat, and topiroxostat. Febuxostat is effective at ULT compared to allopurinol and could be potentially offered as an alternative agent when patients (1) have CKD, (2) have the human leukocyte antigen HLA-B*5801 allele, and (3) become refractory to allopurinol. Gradual allopurinol dose increase with a lower starting dose is needed in CKD.

Interventions for reducing inflammation in familial Mediterranean fever

BACKGROUND

Familial Mediterranean fever (FMF), a hereditary auto-inflammatory disease, mainly affects ethnic groups living in the Mediterranean region. Early studies reported colchicine may potentially prevent FMF attacks. For people who are colchicine-resistant or intolerant, drugs such as anakinra, rilonacept, canakinumab, etanercept, infliximab or adalimumab might be beneficial. This is an update of the review last published in 2018.

OBJECTIVES

To evaluate the efficacy and safety of interventions for reducing inflammation in people with FMF.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and four Chinese databases on in August 2021. We searched clinical trials registries and references listed in relevant reports. The last search was 17 August 2021.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of people with FMF, comparing active interventions (including colchicine, anakinra, rilonacept, canakinumab, etanercept, infliximab, adalimumab, thalidomide, tocilizumab, interferon-α and ImmunoGuard (herbal dietary supplement)) with placebo or no treatment, or comparing active drugs to each other.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology. We assessed certainty of the evidence using GRADE.

MAIN RESULTS

We included 10 RCTs with 312 participants (aged three to 53 years), including five parallel and five cross-over designed studies. Six studies used oral colchicine, one used oral ImmunoGuard, and the remaining three used rilonacept, anakinra or canakinumab as a subcutaneous injection. The duration of each study arm ranged from one to eight months. There were inadequacies in the design of the four older colchicine studies and the two studies comparing a single to a divided dose of colchicine. However, the four studies of ImmunoGuard, rilonacept, anakinra and canakinumab were generally well-designed.  We aimed to report on the number of participants experiencing an attack, the timing of attacks, the prevention of amyloid A amyloidosis, adverse drug reactions and the response of a number of biochemical markers from the acute phase of an attack; but no study reported on the prevention of amyloid A amyloidosis. Colchicine (oral) versus placebo After three months, colchicine 0.6 mg three times daily may reduce the number of people experiencing attacks (risk ratio (RR) 0.21, 95% confidence interval (CI) 0.05 to 0.95; 1 study, 10 participants; low-certainty evidence). One study (20 participants) of colchicine 0.5 mg twice daily showed there may be no difference in the number of participants experiencing attacks at two months (RR 0.78, 95% CI 0.49 to 1.23; low-certainty evidence). There may be no differences in the duration of attacks (narrative summary; very low-certainty evidence), or in the number of days between attacks: (narrative summary; very low-certainty evidence). Regarding adverse drug reactions, one study reported loose stools and frequent bowel movements and a second reported diarrhea (narrative summary; both very low-certainty evidence). There were no data on acute-phase response. Rilonacept versus placebo There is probably no difference in the number of people experiencing attacks at three months (RR 0.87, 95% CI 0.59 to 1.26; moderate-certainty evidence).  There may be no differences in the duration of attacks (narrative summary; low-certainty evidence) or in the number of days between attacks (narrative summary; low-certainty evidence). Regarding adverse drug reactions, the rilonacept study reported there may be no differences in gastrointestinal symptoms, hypertension, headache, respiratory tract infections, injection site reactions and herpes, compared to placebo (narrative summary; low-certainty evidence). The study narratively reported there may be no differences in acute-phase response indicators after three months (low-certainty evidence). ImmunoGuard versus placebo The ImmunoGuard study observed there are probably no differences in adverse effects (moderate-certainty evidence) or in acute-phase response indicators after one month of treatment (moderate-certainty evidence). No data were reported for the number of people experiencing an attack, duration of attacks or days between attacks. Anakinra versus placebo A study of anakinra given to 25 colchicine-resistant participants found there is probably no difference in the number of participants experiencing an attack at four months (RR 0.76, 95% CI 0.54 to 1.07; moderate-certainty evidence).  There were no data for duration of attacks or days between attacks. There are probably no differences between anakinra and placebo with regards to injection site reaction, headache, presyncope, dyspnea and itching (narrative summary; moderate-certainty evidence). For acute-phase response, anakinra probably reduced C-reactive protein (CRP) after four months (narrative summary; moderate-certainty evidence). Canakinumab versus placebo Canakinumab probably reduces the number of participants experiencing an attack at 16 weeks (RR 0.41, 95% CI 0.26 to 0.65; 1 study, 63 colchicine-resistant participants; moderate-certainty evidence). There were no data for the duration of attacks or days between attacks. The included study reported the number of serious adverse events per 100 patient-years was probably 42.7 with canakinumab versus 97.4 with placebo among people with colchicine-resistant FMF (moderate-certainty evidence). For acute-phase response, canakinumab probably caused a higher proportion of participants to have a CRP level of 10 mg/L or less compared to placebo (68% with canakinumab versus 6% with placebo; 1 study, 63 participants; moderate-certainty evidence). Colchicine single dose versus divided dose There is probably no difference in the duration of attacks at three months (MD -0.04 hours, 95% CI -10.91 to 10.83) or six months (MD 2.80 hours, 95% CI -5.39 to 10.99; moderate-certainty evidence). There were no data for the number of participants experiencing an attack or days between attacks. There is probably no difference in adverse events (including anorexia, nausea, diarrhea, abdominal pain, vomiting and elevated liver enzymes) between groups (narrative summary; moderate-certainty evidence). For acute-phase response, there may be no evidence of a difference between groups (narrative summary; low- to moderate-certainty evidence).

AUTHORS' CONCLUSIONS

There were limited RCTs assessing interventions for people with FMF. Based on the evidence, three times daily colchicine may reduce the number of people experiencing attacks, colchicine single dose and divided dose may not be different for children with FMF, canakinumab probably reduces the number of people experiencing attacks, and anakinra or canakinumab probably reduce CRP in colchicine-resistant participants; however, only a few RCTs contributed data for analysis. Further RCTs examining active interventions, not only colchicine, are necessary before a comprehensive conclusion regarding the efficacy and safety of interventions for reducing inflammation in FMF can be drawn.

Extracts of Andrographis paniculata (Burm.f.) Nees Leaves Exert Anti-Gout Effects by Lowering Uric Acid Levels and Reducing Monosodium Urate Crystal-Induced Inflammation

Andrographis paniculata (Burm.f.) Nees has been found to have anti-inflammatory and immunostimulatory effects. This study was to investigate antihyperuricemic and anti-inflammatory effects of A. paniculata leaf extracts. Andrographolide, 14-deoxy-11,12-didehydroandrographolide, and neoandrographolide were quantified in 80% ethanol (EtOH80) and water extracts using High Performance Liquid Chromatography (HPLC) analysis. Antihyperuricemic activity was evaluated using a spectrophotometric in vitro inhibitory xanthine oxidase (XO) assay. The most active extract and andrographolide were further investigated in a hyperuricemic rat model induced by potassium oxonate to determine serum uric acid levels, liver XO activity, followed by Western blot analysis for renal urate transporter URAT1, GLUT9, and OAT1 to investigate the excretion of uric acid via kidney. Anti-inflammatory activity was assessed by in vitro interleukin assay for interleukin (IL-1α, IL-1β, IL-6, IL-8), and tumor necrosis factor (TNF-α) in monosodium urate (MSU) crystal-induced human fibroblast-like synoviocyte (HFLS) cells using ELISA-kits, followed by Western blot analysis for the expression of MyD88, NLRP3, NF-κB p65, and caspase-1 proteins to investigate the inflammation pathway. In vivo assay of the most active extract and andrographolide were performed based on the swelling rate and inhibition of pro-inflammatory mediator release from synovial fluid of a rat knee joint induced by MSU crystals. The results showed that the EtOH80 extract had a greater amount of andrographolide (11.34% w/w) than the water extract (1.38% w/w). In the XO inhibitory activity, none of the samples exhibited greater than 50% inhibition. However, in a rat model, EtOH80 extract (200 mg/kg/day) and andrographolide (30 mg/kg/day) decreased serum uric acid levels and reduced liver XO activity, reduced the protein expression levels of URAT1 and GLUT9, and restored the decrease in OAT1 levels. In the in vitro anti-inflammatory study, EtOH80 extract and andrographolide significantly decreased production of IL-1α, IL-1β, IL-6, and TNF-α, as well as inhibited the synthesis of MyD88, NLRP3, NF-κB p65, and caspase-1 in a concentration-dependent manner, almost comparable to dexamethasone. The EtOH80 extract (200 mg/kg/day) and andrographolide (30 mg/kg) significantly decreased swelling rate and IL-1α, IL-1β, IL-6, and TNF-α in the synovial fluid of rat models in a time-dependent manner, comparable to indomethacin (3 mg/kg/day). In conclusion, the findings show that EtOH80 extract has a substantial anti-gout effect by lowering uric acid levels and suppressing pro-inflammatory mediator production due to the andrographolide content, that might be beneficial in the treatment of gouty-inflammation.

Glucagon-Like Peptide-1 Receptor Regulates Macrophage Migration in Monosodium Urate-Induced Peritoneal Inflammation

Glucagon-like peptide-1 (GLP-1) is an insulinotropic peptide that signals through the GLP-1 receptor (GLP-1R). GLP-1R, therefore, plays a critical role in diabetes and cardiovascular disease. Whether GLP-1R is involved in inflammatory disease such as gout remains unclear. Macrophages are critical effector cells in the pathogenesis of gout, a common form of inflammatory arthritis caused by the deposition of uric acid in joints. The expression of GLP-1R at the protein level is controversial due to the lack of specificity of existing antibodies against GLP-1R. Using a transgenic mouse model expressing enhanced green fluorescent protein (EGFP) under the control of GLP-1R promoter, here we confirmed the expression of GLP-1R by macrophages. M2 type macrophages and Ly6C⁺ macrophages expressed higher levels of GLP-1R, compared to their counterparts. GLP-1R deficient macrophages displayed a reduced the migratory ability and an enhanced expression of interleukin (IL)-6, while the expression of IL-1β was not affected. In monosodium urate (MSU) crystal-induced peritonitis, an experimental model of gout, the recruitment of macrophages, especially M2 macrophages, was significantly suppressed in GLP-1R knockout mice compared to wild-type mice. In conclusion, our data suggests that GLP-1R plays a critical role in macrophage migration in MSU-induced inflammation.

Influence of Pinealectomy and Long-term Melatonin Administration on Inflammation and Oxidative Stress in Experimental Gouty Arthritis

Gout is an inflammatory arthritis characterized by the deposition of monosodium urate (MSU) crystals in the joints or soft tissue. MSU crystals are potent inflammation inducers. Melatonin (MLT) is a powerful endogenous anti-inflammatory agent and effective in reducing cellular damage. In the present study, possible underlying mechanisms associated with anti-inflammatory and antioxidative effects were investigated in rats with gouty arthritis and melatonin deprivation treated with MLT. Fifty-six rats were divided into seven groups: control, sham control, pinealectomy (PNX), MSU (on the 30th day, single-dose 20 mg/ml, intraperitoneal), MSU + MLT (10 mg/kg/day for 30 days, intraperitoneal), MSU + PINX and MSU + PINX + MLT. PNX procedure was performed on the first day of the study. As compared to the controls, the results showed that MSU administration caused significant increases in oxidative stress parameters (malondialdehyde and total oxidant status). Besides, significant decreases in antioxidant defense systems (glutathione, superoxide dismutase and total antioxidant status) were observed. A statistically significant increase was found in the mean histopathological damage score in the groups that received MSU injection. It was found that histopathological changes were significantly reduced in the MSU + MLT group given MLT. In our study, it was determined that many histopathological changes, as well as swelling and temperature increase in the joint, which are markers of inflammation, were significantly reduced with MLT supplementation. These results suggest that melatonin ameliorates MSU-induced gout in the rat through inhibition of oxidative stress and proinflammatory cytokine production.

Quantitative proteomics by iTRAQ-PRM based reveals the new characterization for gout

Background

Gout is a common and complex form of immunoreactive arthritis based on hyperuricemia, while the symptoms would turn to remission or even got worse. So, it is hard to early identify whether an asymptomatic hyperuricemia (AHU) patient will be susceptible to get acute gout attack and it is also hard to predict the process of gout remission to flare. Here, we report that the plasma proteins profile can distinguish among acute gout (AG), remission of gout (RG), AHU patients, and healthy controls.

Methods

We established an isobaric tags for relative and absolute quantification (iTRAQ) and parallel reaction monitoring (PRM) based method to measure the plasma proteins for AG group (n = 8), RG group (n = 7), AHU group (n = 7) and healthy controls (n = 8).

Results

Eleven differentially expressed proteins such as Histone H2A, Histone H2B, Thrombospondin-1 (THBS1), Myeloperoxidase (MPO), Complement C2, Complement component C8 beta chain (C8B), Alpha-1-acid glycoprotein 1 (ORM1), Inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4), Carbonic anhydrase 1 (CA1), Serum albumin (ALB) and Multimerin-1 (MMRN1) were identified. Histone H2A, Histone H2B and THBS1 might be the strongest influential regulator to maintain the balance and stability of the gout process. The complement and coagulation cascades is one of the main functional pathways in the mechanism of gout process.

Conclusions

Histone H2A, Histone H2B and THBS1 are potential candidate genes for novel biomarkers in discriminating gout attack from AHU or RG, providing new theoretical insights for the prognosis, treatment, and management of gout process.

Trial registration

This study is not a clinical trial.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12953-021-00180-0.

Network Pharmacology Study on Morus alba L. Leaves: Pivotal Functions of Bioactives on RAS Signaling Pathway and Its Associated Target Proteins against Gout

M. alba L. is a valuable nutraceutical plant rich in potential bioactive compounds with promising anti-gouty arthritis. Here, we have explored bioactives, signaling pathways, and key proteins underlying the anti-gout activity of M. alba L. leaves for the first-time utilizing network pharmacology. Bioactives in M. alba L. leaves were detected through GC-MS (Gas Chromatography-Mass Spectrum) analysis and filtered by Lipinski's rule. Target proteins connected to the filtered compounds and gout were selected from public databases. The overlapping target proteins between bioactives-interacted target proteins and gout-targeted proteins were identified using a Venn diagram. Bioactives-Proteins interactive networking for gout was analyzed to identify potential ligand-target and visualized the rich factor on the R package via the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway on STRING. Finally, a molecular docking test (MDT) between bioactives and target proteins was analyzed via AutoDock Vina. Gene Set Enrichment Analysis (GSEA) demonstrated that mechanisms of M. alba L. leaves against gout were connected to 17 signaling pathways on 26 compounds. AKT1 (AKT Serine/Threonine Kinase 1), γ-Tocopherol, and RAS signaling pathway were selected as a hub target, a key bioactive, and a hub signaling pathway, respectively. Furthermore, three main compounds (γ-Tocopherol, 4-Dehydroxy-N-(4,5-methylenedioxy-2-nitrobenzylidene) tyramine, and Lanosterol acetate) and three key target proteins-AKT1, PRKCA, and PLA2G2A associated with the RAS signaling pathway were noted for their highest affinity on MDT. The identified three key bioactives in M. alba L. leaves might contribute to recovering gouty condition by inactivating the RAS signaling pathway.

Clinical and immunologic differences in cellulitis vs. pseudocellulitis

Introduction: The immunologic mechanisms between cellulitis and pseudocellulitis differ greatly, even though their clinical presentations may overlap.Areas covered: This article discusses cellulitis and common entities within the pseudocellulitis spectrum including acute lymphedema, superficial venous thrombosis, allergic contact dermatitis, lipodermatosclerosis, stasis dermatitis, erythema nodosum, cutaneous gout, and bursitis. The literature search was conducted from PubMed search engine between March and May 2021.Expert commentary: While immunologic differences in cellulitis and the various entities of pseudocellulitis are clear, there is a practice gap in applying these differences to the clinic and hospital setting. Further, existing studies are weakened by the lack of a gold-standard diagnosis in this disease category. Additional work is necessary in developing a gold-standard for the diagnosis and secondly, to project these immunologic differences as biomarkers to differentiate sterile inflammation from a potential life threatening bacterial or fungal infection.

Simiao Wan attenuates monosodium urate crystal-induced arthritis in rats through contributing to macrophage M2 polarization

ETHNOPHARMACOLOGICAL RELEVANCE

Simiao Wan (SMW) is a classical traditional Chinese medicine (TCM) prescription to empirically treat gouty arthritis (GA) in TCM clinical practice. However, the potential mechanisms of SMW on GA are not fully evaluated.

AIM OF STUDY

The aim of this study is to investigate the role of macrophage polarization in the anti-GA activity of SMW.

MATERIALS AND METHODS

Rats were intragastricly treated with SMW for consecutive 7 days. On day 6, monosodium urate (MSU) crystal-induced arthritis (MIA) in the ankle joint was prepared. Paw volume, gait score and histological score were measured. Levels of interleukin (IL)-1β and IL-10 in serum were detected by enzyme-linked immunosorbent assay. Expressions of inducible nitric oxide synthase (iNOS), arginase (Arg)-1, phosphorylated (p)-p65, inhibitor of nuclear factor (NF)-κB (IκB)α, p-signal transducer and transcription activator (STAT)3 and p-Janus kinase (JAK)2 in synovial tissues were determined by Western blot.

RESULTS

The elevated paw volume, gait score and histological score in MIA rats were significantly decreased by SMW treatment. Meanwhile, SMW significantly decreased the IL-1β level and increased the IL-10 level in serum of MIA rats. Furthermore, SMW reduced the expressions of iNOS, p-p65 and enhanced the expressions of Arg-1, IκBα, p-STAT3 and p-JAK2 in synovial tissues of MIA rats.

CONCLUSIONS

The results suggest that SMW attenuates the inflammation in MIA rats through promoting macrophage M2 polarization.

Contentious Issues in Gout Management: The Story so Far

Gout is the most common inflammatory arthritis worldwide. Although gout has been known for antiquity, many challenges still exist in gout management. It is vital to view gout as a chronic disease and not just treat the acute flare. There is a perception of gout as an acute disease requiring treatment only for acute flares. However, to combat the disease, chronic urate-lowering therapy, reducing the serum urate levels to below the saturation threshold of 6.8 mg/dL, and chronic anti-inflammatory prophylaxis, especially during urate-lowering therapy initiation, are needed. In this manuscript, we discuss some of the contentious issues in gout management. These include the timing of urate-lowering therapy initiation, which urate-lowering therapy to chose, should comorbidities influence our treatment, using genetic determinants, and patient perspectives to drive treatment and differences between gout treatment the American College of Physicians and Rheumatology guidelines for gout management: driving care.

A new prenylated benzoquinone from Cyathocalyx pruniferus abrogates LPS-induced inflammatory responses associated with PGE2, COX-2 and cytokines biosynthesis in human plasma

In our previous laboratory findings, Cyathocalyx pruniferus extracts exhibited platelet-activating factor inhibition, suggesting their anti-inflammatory potential. Hence, this study was designed with the aim to isolate phyto-constituents from C. pruniferus with potent anti-inflammatory activities. Column and volume liquid chromatography were used for isolation of phyto-constituents. The structure elucidation was carried out using spectroscopic analysis (HRESI-MS, ¹H and ¹³C-NMR) and compared with published literature. For cytotoxicity analysis, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide assay was performed on peripheral blood mononuclear cells. Anti-inflammatory activities were evaluated against the levels of inflammatory cytokines (IL-1β and IL-6), prostaglandin-E₂ (PGE₂) and cyclooxegenase-2 (COX-2), in lipopolysaccharide (LPS)-induced human plasma using ELISA and radioimmunoassay (RIA). The chromatographic purification of methanol leaves extract afforded 13 (1-13) secondary metabolites. Additionally, cytotoxicity analysis suggested that isolates were non-cytotoxic at 100 μM. In anti-inflammatory evaluation, 2-octaprenyl-1, 4-benzoquinone (5) produced strong (≥ 70%) inhibition of PGE₂, COX-2, IL-1β and IL-6 at 50 µM. Moreover, 2-octaprenyl-1,4-benzoquinone (5) exhibited concentration-dependent inhibition with IC₅₀ values (µM) of 11.21, 6.61, 2.20 and 3.56 as compared to controls; indomethacin for PGE₂ (11.84) and dexamethasone in COX-2 (5.19), IL-1β (1.83) and IL-6 (3.76) analysis, respectively. In conclusion, two new compounds including 2-octaprenyl-1, 4-benzoquinone (5) and 14-methyloctadec-1-ene (6) are reported for the first time from plant species. Additionally, 2-octaprenyl-1, 4-benzoquinone (5) dose-dependently suppressed the production of pro-inflammatory mediators involved in acute and chronic inflammation at non-cytotoxic concentrations.

Optimization of culture medium for Sanghuangporus vaninii and a study on its therapeutic effects on gout

The increasing incidence of gout poses a very challenging management problem. However, the currently available drugs often have various toxic side effects. As a traditional edible and medicinal macrofungus, Sanghuangporus vaninii presents high medical research value. Therefore, to improve fermentation efficiency and identify novel anti-gout drugs, we optimized the culture medium of S. vaninii with lignin and further investigated its anti-gout effects. The results indicated that 0.06 g/L of lignin was most favorable for S. vaninii growth. In the hyperuricemia cell model, we found that S. vaninii could significantly induce the downregulation of xanthine oxidoreductase and the upregulation of hypoxanthine-guanine phosphoribosyltransferase. Furthermore, following oral administration of the extracts, the serum uric acid levels of mice with hyperuricemia were effectively reduced. In a gouty arthritis rat model, S. vaninii also achieved strong suppression of synovial swelling, indicating its anti-inflammatory activity. In addition, the antioxidant assays suggested that S. vaninii shows a strong free radical scavenging capacity and can effectively alleviate cellular oxidative stress. This activity further enhances its anti-inflammatory activity and reduces the incidence of comorbidities. In summary, our results provide the basis for the utilization of S. vaninii to develop anti-gout drugs.

Withaferin A protects against hyperuricemia induced kidney injury and its possible mechanisms

The study was designed to explore the effects of Withaferin A (WFA) on hyperuricemia-induced kidney injury and its action mechanism. Potassium oxonate (PO) was employed to establish the hyperuricemic mouse model. The pathological changes of renal tissue were evaluated by hematoxylin-eosin and masson trichrome staining. The levels of creatinine, blood urea nitrogen (BUN), uric acid (UA) and xanthine oxidase (XOD) were detected using corresponding commercial kits. Expressions of collagen-related and apoptosis-associated proteins in renal tissues were, respectively, evaluated by immunofluorescence and western blotting. Cell apoptosis was detected by TUNEL assay, and transporter expressions using western blotting. Followed by WFA, NRK-52E cells were treated with UA before evaluation of apoptosis and fibrosis. Results indicated that WFA ameliorated renal damage, improved kidney function, and decreased levels of creatinine, BUN, UA, and XOD in PO-induced hyperuricemic mice. Furthermore, WFA significantly prevented renal fibrosis and increased the expression of collagen-related proteins. Similarly, WFA markedly inhibited renal apoptosis, accompanied by changes of apoptosis-related proteins. Importantly, expression of transporters responsible for the secretion of organic anion transporter 1 (OAT1), OAT3, ATP-binding cassette subfamily G member 2 (ABCG2) was remarkably enhanced whereas that of urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) was reduced in renal tissues of mice with hyperuricemia. In vitro study revealed that WFA notably ameliorated UA-induced cell fibrosis and apoptosis. Taken together, WFA improves kidney function by decreasing UA via regulation of XOD and transporter genes in renal tubular cells.

Identification of Active Compounds From Yi Nationality Herbal Formula Wosi Influencing COX-2 and VCAM-1 Signaling

The Yi nationality herbal formula Wosi is used in China as a folk medicine to treat arthritis and related diseases. Despite its widespread use, the active ingredients, and pharmacological mechanisms are not performed. This is the first time to identify the active compounds from Wosi with the aim at providing the potential effect of Wosi and exploring its underlying anti-inflammatory mechanism in monosodium urate crystals (MSU)-induced arthritis rats. In this study, anti-hyperuricemia effect was assessed by reducing the serum uric acid levels and increasing uric acid excretion in the urine for the hyperuricemia rat model. Wosi significantly suppressed the degree of joint swelling and improved the symptoms of inflammation induced by MSU crystals. The inhibition of IL-2, IL-1β, IFN-γ, and IL-6 secretion and IL-10 increase in the serum were also observed. This study also focuses on the screening of the main compounds from Wosi against cyclooxygenase for anti-inflammatory properties using molecular docking. The result showed 3-O-[α-L-pyran rhamnose(1-3)-β-D-pyran glucuronic acid]- oleanolic acid, 3-O-(β-D-pyran glucuronic acid)-oleanolic acid-28-O-β-D-pyran glucoside, and 3-O-[α-L-pyran rhamnose(1-3)-β-D-pyran glucuronic acid]-oleanolic acid-28-O-β-D-pyran glucoside with a higher binding affinity for COX-2 than COX-1 which indicated relatively higher interaction than COX-1. The preferential selectivity toward inhibiting COX-2 enzyme over COX-1 of three compounds from Wosi were evaluated using in-vitro cyclooxygenases 1 and 2 (COX-1/2) inhibition assays. Meanwhile, the down-regulated protein expression of COX-2 and VCAM-1 in synovial tissue sections from ankle joints of experiments rats were confirmed by immunohistochemistry analysis after the Wosi treatment. In conclusion, three oleanolic acid glycosides were implied as mainly efficient compounds in Yi nationality herbal formula Wosi for arthritis therapy via selectively influencing COX-2 and VCAM-1 signaling.

Piperazine: A Promising Scaffold with Analgesic and Anti-inflammatory Potential

Piperazine, a nitrogen-containing heterocyclic has acquired an inimitable position in medicinal chemistry because of its versatile structure, which has fascinated researchers to design novel piperazine based molecules having various biological actions. The subsistence of various compounds possessing diverse pharmacological activities in the literature further confirms this fact. Currently available analgesics and anti-inflammatory drugs are associated with side effects that limit their use. Moreover, the literature reveals the incredible anti-inflammatory and analgesic potential of piperazine derivatives along with their method of synthesis, therefore; the present review has been designed to collate the development made in this area that will surely be advantageous in designing novel piperazine based candidates with enhanced efficacy and less toxicity. An extensive literature survey was carried by scrutinizing peer reviewed articles from worldwide scientific databases available on GOOGLE, SCOPUS, PUBMED, and only relevant studies published in English were considered.

Characteristics, Comorbidities, and Potential Consequences of Uncontrolled Gout: An Insurance-Claims Database Study

INTRODUCTION

Gout is a common, progressive, systemic inflammatory arthritis caused by hyperuricemia. Current guidelines recommend that serum uric acid (sUA) levels be maintained below 6.0 mg/dl to minimize acute gout attacks, tophi development, and long-term joint and organ damage. This study examined the influence of uncontrolled gout on post-diagnosis comorbidities and medication use.

METHODS

The Humana Research Database (2007-2016, commercial insurance and Medicare) was searched (PearlDiver tool) for patients who had a gout diagnosis code, claims data for at least 6 months before and after diagnosis, and at least 90 days of continuous urate-lowering therapy within 1 year of diagnosis. Patients with controlled (all sUA measurements < 6.0 mg/dl) and uncontrolled (all sUA measurements ≥ 8.0 mg/dl) gout were further examined and compared to better understand the influence of uncontrolled gout on post-diagnosis comorbidities, medication use, and reasons for seeking medical care.

RESULTS

A total of 5473 and 1358 patients met inclusion and classification criteria for the controlled and uncontrolled groups, respectively. Identified comorbidities in both groups included hypertension, hyperlipidemia, diabetes, cardiovascular disease, and chronic kidney disease (CKD). However, the uncontrolled group was more likely to have diabetes, CKD, and cardiovascular disease (including heart failure and atrial fibrillation). Additionally, CKD tended to be more advanced in the uncontrolled gout population (Stage 4-5: 34.6 vs. 22.2%). Overall opioid use was higher in uncontrolled patients.

CONCLUSIONS

The current study identified differences between controlled and uncontrolled gout patients, including usage of medication, severity of CKD, and prevalence of CKD, diabetes, and heart disease.

Apamin from bee venom suppresses inflammation in a murine model of gouty arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Bee venom (BV) has been used for the treatment of inflammatory diseases, such as rheumatoid arthritis, and for the relief of pain in traditional oriental medicine.

AIM OF STUDY

The aim of this study was to determine the anti-inflammatory effect of BV on monosodium urate (MSU)-induced gouty arthritis in a mouse model.

MATERIALS AND METHODS

To develop a mouse model of acute gouty arthritis, 4 mg 50 μL^-1 of MSU crystal suspension was injected intradermally into the right paw. After MSU crystal injection, we evaluated inflammatory cytokine production in mice of the BV-treated (0.5 and 1 mg kg^-1 body weight) and apamin (APM)-treated (0.5 and 1 mg kg^-1 body weight) groups. The positive control group was administered a colchicine (1 mg kg^-1 body weight) injection with MSU crystals.

RESULTS

BV and APM treatment suppressed inflammatory paw edema in MSU-administered mice. It also exerted anti-inflammatory effects in mice with gouty arthritis by inhibiting proinflammatory cytokine production and inflammasome formation. Interestingly, MSU crystal formation was decreased by BV and APM treatment.

CONCLUSIONS

These results suggest that the APM from BV might be useful for the treatment of gouty arthritis due to its anti-inflammatory activities.

1-Palmitoyl-2-Linoleoyl-3-Acetyl-rac-Glycerol (PLAG) Mitigates Monosodium Urate (MSU)-Induced Acute Gouty Inflammation in BALB/c Mice

Acute gouty arthritis is an auto-inflammatory disease caused by the deposition of monosodium urate (MSU) crystals in joints or tissues. Excessive neutrophil recruitment into gouty lesions is a general clinical sign and induces a pain phenotype. Attenuation of successive periods of neutrophil infiltration might be a beneficial approach to achieve therapeutic efficacy. In this study, the activity of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) in attenuation of excess neutrophil infiltration was assessed in gout-induced lesions of BALB/c mice. Neutrophil infiltration in MSU-induced gouty lesions was analyzed using immunohistochemical staining. ELISA and RT-PCR were used to measure attenuation of expression of the major neutrophil chemoattractant, CXC motif chemokine ligand 8 (CXCL8), in a PLAG-treated animal model and in cells in vitro. The animal model revealed massive increased neutrophil infiltration in the MSU-induced gouty lesions, but the PLAG-treated mice had significantly reduced neutrophil numbers in these lesions. The results also indicated that the MSU crystals stimulated a damage-associated molecular pattern that was recognized by the P2Y6 purinergic receptor. This MSU-stimulated P2Y6 receptor was destined to intracellular trafficking. During intracellular endosomal trafficking of the receptor, endosome-dependent signaling provided expression of CXCL8 chemokines for neutrophil recruitment. PLAG accelerated initiation of the intracellular trafficking of the P2Y6 receptor and returning the receptor to the membrane. This process shortened the intracellular retention time of the receptor anchoring endosome and subsequently attenuated endosome-dependent signaling for CXCL8 expression. These study results suggested that PLAG could be used for resolution of acute inflammation induced in gout lesions.

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.

Lychnophora pinaster ethanolic extract and its chemical constituents ameliorate hyperuricemia and related inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Lychnophora pinaster, known as "Brazilian arnica" is used in folk medicine as alcoholic extract to treat inflammation, pain, rheumatism and bruises.

AIM OF THE STUDY

Evaluate the effects of the Lychnophora pinaster's ethanolic extract and its chemical constituents on inflammation and hyperuricemia.

MATERIALS AND METHODS

Ethanolic and hexanic extracts were obtained from the aerial parts of L. pinaster. Sesquiterpene E-lychnophoric acid was isolated from hexanic extract and identified by RMN, GC/MS and IR. In vivo anti-hyperuricemic and anti-inflammatory effects of the ethanolic extracts from L. pinaster (40, 125, 375 mg/kg), E-lychnophoric acid and other constituents previous isolated from L. pinaster and identified in the ethanolic extract by HPLC/UV/DAD (rutin, quercetin and vitexina flavonoids, caffeic, cinnamic and chlorogenic acids, lupeol and stigmasterol, at dose of 15 mg/kg) were assayed by experimental model of oxonate-induced hyperuricemia in Swiss mice, liver xanthine oxidase (XOD) inhibition and by MSU-induced paw edema in mice.

RESULTS

Ethanolic extract and all its components presented anti-hyperuricemic activity by inhibiting the hepatic xanthine oxidase activity. Ethanolic extract and its chemical constituents, except quercetin and vitexin, were able to reduce paw edema size induced by urate crystals. Hypouricemic and anti-inflammatory results obtained for the ethanolic extract (40, 125, 375 mg/kg) and E-lychnophoric acid (15 mg/kg) were similar those obtained for standard drugs, allopurinol (10 mg/kg) and indomethacin (3 mg/kg).

CONCLUSION

Ethanolic extract and E-lychnophoric, chlorogenic, cinnamic and caffeic acids, rutin, lupeol and stigmasterol presented anti-inflammatory and anti-hyperuricemic actvities. These compounds are responsible for the activities presented by the ethanolic extract of L. pinaster. Ethanolic extract and its chemical constituents can be considered promising agents in the therapeutic of inflammation, hyperuricemia and gout.

Anti‑gouty arthritis and anti‑hyperuricemia properties of celery seed extracts in rodent models

Gout is a type of serious arthritis that is caused by hyperuricemia. Celery is an umbelliferous plant that was shown to exhibit anti‑inflammatory activity in rodent. The present study aimed to investigate the effects and potential preliminary mechanisms of celery seed aqueous extract (CSAE) and celery seed oil extract (CSOL) for gout treatment. The components of CSAE and CSOL were systematically analyzed. In mice with hyperuricemia induced by potassium oxonate and yeast extract, CSAE and CSOL treatment reduced the serum levels of uric acid and xanthine oxidase. In addition, CSAE and CSOL reduced the levels of reactive oxygen species and increased the serum levels of superoxide dismutase and glutathione peroxidase in mouse serum. In rats with acute gouty arthritis induced by intra‑articular injection of monosodium urate crystals, CSAE and CSOL treatment alleviated the swelling of the ankle joints and reduced inflammatory cell infiltration around the ankle joints. In addition, CSAE and CSOL reduced the levels of interleukin (IL)‑1β and tumor necrosis factor α and increased the levels of IL‑10. The results of the present study suggested that celery seed extracts may have anti‑gout properties, partially through anti‑inflammatory and antioxidative effects.

Phosphoinositide-3 kinase gamma regulates caspase-1 activation and leukocyte recruitment in acute murine gout

This study investigates the participation of PI3Kγ in the development of joint inflammation and dysfunction in an experimental model of acute gout in mice. Acute gout was induced by injection of monosodium urate (MSU) crystals into the tibiofemoral joint of mice. The involvement of PI3Kγ was evaluated using a selective inhibitor and mice deficient for PI3Kγ (PI3Kγ^-/- ) or with loss of kinase activity. Neutrophils recovered from the inflamed joint were quantified and stained for phosphorylated Akt (pAkt) and production of reactive oxygen species (ROS). The adherence of leukocytes to the joint microvasculature was assessed by intravital microscopy and cleaved caspase-1 by Western blot. Injection of MSU crystals induced massive accumulation of neutrophils expressing phosphorylated Akt. In the absence of PI3Kγ, there was reduction of pAkt expression, chemokine production, and neutrophil recruitment. Genetic or pharmacological inhibition of PI3Kγ reduced the adherence of leukocytes to the joint microvasculature, even in joints with established inflammation. Neutrophils from PI3Kγ^-/- mice produced less ROS than wild-type neutrophils. There was decreased joint damage and dysfunction in the absence of PI3Kγ. In addition, in the absence of PI3Kγ activity, there was reduction of cleaved caspase-1 and IL-1β production in synovial tissue after injection of MSU crystals and leukotriene B₄ . Our studies suggest that PI3Kγ is crucial for MSU crystal-induced acute joint inflammation. It is necessary for regulating caspase-1 activation and for mediating neutrophil migration and activation. Drugs that impair PI3Kγ function may be useful to control acute gout inflammation.

Nerve modulation therapy in gouty arthritis: targeting increased sFRP2 expression in dorsal root ganglion regulates macrophage polarization and alleviates endothelial damage

Gouty arthritis (GA) is a form of arthritis caused by uric acid deposition in the joints that result in intense inflammation and pain. Accumulating evidence showed the importance of the sensory neurons signal upon immune cells by releasing neuropeptides and chemokines to regulate associated immune-inflammatory response. In this study, we investigated the significance of sensory neuron neuropeptides and chemokine signals on inflammation-induced macrophages polarization during GA.

Methods: We screened the mRNA expression profile during GA in dorsal root ganglion (DRG) neurons to identify the most likely candidate that mediates the neuro-immune communication. Then, we silenced specific gene expression in the DRG by lentiviral vectors in the monosodium urate (MSU)-induced ankle GA mouse model and evaluated alterations in the inflammatory response. In vitro, primary macrophages were used to investigate the neural impact on M1/M2 subtype polarization, proinflammatory cytokine production and downstream endothelial damage. Mechanism by which macrophage inflammation is induced in the DRG was evaluated by Western blot, immunofluorescence, and immunoprecipitation.

Results: We found that secreted frizzled-related protein 2 (sFRP2) was the most upregulated gene in dorsal root ganglion (DRG) neurons in response to monosodium urate (MSU) deposition. Injection of LV-sFRP2-shRNA into the L4 and L5 DRG significantly suppressed inflammatory cell infiltration and M1 polarization in the synovial membrane, attenuating hyperalgesia and ankle swelling in the GA mouse model. In vitro, DRG neurons-derived sFRP2 promoted M1 polarization and macrophage migration, thereby upregulating the production of proinflammatory cytokines and preventing endothelial apoptosis. Furthermore, DRG-derived sFRP2 activated the nuclear factor (NF)-κB pathway by destabilizing the β-catenin and p65 complex.

Conclusion: We demonstrated the involvement of a sensory neuron-macrophage axis in GA pathology that was regulated by sFRP2 expression in a paracrine manner. Targeting increased sFRP2 expressions in DRG provide novel insights for future GA research in both pain alleviation and treatment of gout inflammation.

Novel colchicine derivatives enhance graft survival after transplantation via suppression of T-cell differentiation and activity

Immunosuppressants are crucial in organ transplantation but their side effects are a trade-off for long-term use. Colchicine has been shown to be effective in various diseases, albeit with many side effects. To enhance the immunosuppressive effects of colchicine, in addition to minimizing its side effects, we attempted to synthesize new colchicine derivatives (KR compounds). In rat cardiac and pancreatic islet allograft, long-term graft survival was identified in KR compound-treated groups. The use of cyclosporine A (CsA) or colchicine inhibited the CD3⁺ and CD4⁺ T-cell proliferation, whereas KR compounds inhibited the CD8⁺ T cells as well as CD4⁺ T cells. KR compounds reduced the apoptosis, interleukin-2 receptor expression, and signal transducer and activator of transcription 3 phosphorylation more than CsA. These results indicate that KR compounds have a potential therapeutic value as novel agents for prevention of graft deterioration by allograft of rejection.

Phagocytosis of monosodium urate crystals by human synoviocytes induces inflammation

IMPACT STATEMENT

Gout is distinguished by an inflammatory process that is mediated by phagocytosis of monosodium urate (MSU) crystals in synoviocytes by regulation of unknown mechanisms. Here we suggest that the synovial cells play a crucial role in gouty arthritis by activating inflammation by MSU uptake and increasing the secretion of pro-inflammatory cytokines IL-1β, IL-6, IL-8, TNF-α, MCP-1, and the growth factors NGF and HGF. We discuss some co-existing features in synoviocytes, including anomalous morphologies of the cells, and microvesicle formation, dysregulation in VEGF gene expression. We provide evidence that phagocytosis of MSU crystals triggers an inflammatory cellular state in synoviocytes in the pathogenesis of crystal-induced arthritis.

Effects of ChondroT on potassium Oxonate-induced Hyperuricemic mice: downregulation of xanthine oxidase and urate transporter 1

Background

ChondroT, a new herbal medication, consists of the water extracts of Osterici Radix, Lonicerae Folium, Angelicae Gigantis Radix, Clematidis Radix, and Phellodendri Cortex (6:4:4:4:3). We previously reported that ChondroT showed significant anti-arthritis and anti-inflammatory effects.

Methods

This study was designed to evaluate the effect of ChondroT on hyperuricemia. First, the effect of ChondroT was evaluated on xanthine oxidase (XOD) activity in vitro. The anti-hyperuricemic effect of ChondroT was also studied in potassium oxonate (PO)-induced hyperuricemic model mice. Uric acid (UA) and XOD were evaluated in the serum, urine, and liver of the mice. In addition, we measured serum creatinine (Cr) and blood urea nitrogen (BUN) levels as well as mRNA expression of the mouse urate transporter 1 (mURAT1) to evaluate kidney function and urate excretion in hyperuricemic mice.

Results

ChondroT showed in vitro XOD inhibitory activity in a dose-dependent manner (P < 0.05). We demonstrated that ChondroT (37.5, 75 and 150 mg/kg) significantly reduced serum UA (P < 0.01 and P < 0.001, respectively), and upregulated urinary UA (P < 0.001, respectively) in PO-induced hyperuricemic mice. In addition, ChondroT (75 and 150 mg/kg) significantly reduced Cr (P < 0.05 and P < 0.01, respectively), BUN (P < 0.05 and P < 0.001, respectively), GOT (P < 0.05 and P < 0.01, respectively), and GPT (P > 0.05 and P < 0.05, respectively) levels in PO-induced hyperuricemic mice. ChondroT (75 and 150 mg/kg) also significantly downregulated serum (P < 0.05) and liver (P < 0.05) XOD activity. Compared to the hyperuricemic mice, the ChondroT (37.5, 75, and 150 mg/kg)-treated mice showed decreased mURAT1 protein expression level.

Conclusion

ChondroT displayed anti-hyperuricemic effects by regulating XOD activity and kidney mURAT1.

IL-33 Ameliorates the Development of MSU-Induced Inflammation Through Expanding MDSCs-Like Cells

Interleukin-33 (IL-33), a member of the IL-1 superfamily, has been shown to play a critical role in many diseases through regulating the immune cell responses, including myeloid-derived suppressor cells (MDSCs). Our previous study demonstrated that IL-33 might play a protective role in kidney injury in gout patients by regulating the lipid metabolism. However, the role of IL-33in the development of MSU-induced inflammation remains elusive. In this study, an increased IL-33 expression was observed in gout patients, which was positively correlated with inflammatory marker CRP. To explore the effects and mechanisms of the increased IL-33 expression in the gout patients, the anti-ST2 antibody and exogenous recombinant IL-33 were used in MSU-induced peritonitis animal model that mimics human gout. Compared with control group, mice with exogenous recombinant IL-33 significantly ameliorated the inflammatory cells infiltration, while blockage of IL-33 signaling by anti-ST2 had no effect on the development of MSU-induced peritonitis. Furthermore, the crucial inflammatory cytokine IL-1β was markedly decreased in IL-33-treated mice. Besides that, a large number of anti-inflammatory MDSCs with CD11b⁺Gr1^intF4/80⁺ phenotype was observed in the IL-33-treated mice, and adoptive transfer of IL-33-induced MDSCs (CD11b⁺Gr1^intF4/80⁺) markedly inhibited the IL-1β production in MSU-induced peritonitis. In conclusion, our data provide clear evidences that the increased expression of IL-33 in the gout patients might be due to a cause of self-negative regulation, which inhibits the development of MSU-induced inflammation through expanding MDSCs. Thus, IL-33 might serve as a promising therapeutic target for gout.

Do etoricoxib and indometacin have similar effects and safety for gouty arthritis? A meta-analysis of randomized controlled trials

Background

Gout, a common medical condition that causes pain, can be treated by painkillers and anti-inflammatories. Indometacin and etoricoxib are two such drugs. However, no synthesized evidence exists comparing etoricoxib with indometacin in treating patients with gout.

Methods

We searched PubMed, Embase, Ovid MEDLINE, Web of Science, ScienceDirect, and the Cochrane Library without restrictions on language or publication date for potential randomized clinical trials comparing etoricoxib with indometacin for gout. The meta-analysis was conducted using a random-effects model.

Results

Search results yielded 313 references from six electronic databases, four of which met the eligibility criteria. These four were randomized clinical trials, and they involved a total of 609 patients with gouty arthritis. No significant differences were observed in pain score change, tenderness, or swelling between etoricoxib and indometacin; the mean differences were −0.05 (95% CI, −0.21 to 0.10), −0.06 (95% CI, −0.18 to 0.05), and −0.04 (95% CI, −0.17 to 0.09). However, the pooled data revealed that significantly fewer overall adverse events occurred in the etoricoxib group (n=105, 33.5%) than in the indometacin group (n=130, 44.1%) and the risk ratio was 0.77 (95% CI, 0.62–0.94).

Conclusion

Our meta-analysis revealed that etoricoxib and indometacin have similar effects on pain relief. However, etoricoxib has a significantly lower risk of adverse events than does indometacin, especially digestive system-related adverse events.

Biochemical Characterization of Kluyveromyces lactis Adenine Deaminase and Guanine Deaminase and Their Potential Application in Lowering Purine Content in Beer

Excess amounts of uric acid in humans leads to hyperuricemia, which is a biochemical precursor of gout and is also associated with various other disorders. Gout is termed as crystallization of uric acid, predominantly within joints. The burden of hyperuricemia and gout has increased worldwide due to lifestyle changes, obesity, and consumption of purine-rich foods, fructose-containing drinks, and alcoholic beverages. Some of the therapies available to cure gout are associated with unwanted side-effects and antigenicity. We propose an attractive and safe strategy to reduce purine content in beverages using enzymatic application of purine degrading enzymes such as adenine deaminase (ADA) and guanine deaminase (GDA) that convert adenine and guanine into hypoxanthine and xanthine, respectively. We cloned, expressed, purified, and biochemically characterized both adenine deaminase (ADA) and guanine deaminase (GDA) enzymes that play important roles in the purine degradation pathway of Kluyveromyces lactis, and demonstrate their application in lowering purine content in a beverage. The popular beverage beer has been selected as an experimental sample as it confers higher risks of hyperuricemia and gout. Quantification of purine content in 16 different beers from the Indian market showed varying concentrations of different purines. Enzymatic treatment of beer samples with ADA and GDA showed a reduction of adenine and guanine content, respectively. These enzymes in combination with other purine degrading enzymes showed marked reduction in purine content in beer samples. Both enzymes can work at 5.0–8.0 pH range and retain >50% activity at 40°C, making them good candidates for industrial applications.