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Gouty inflammation, caused by uric acid crystal deposition, primarily affects tissues around the toe joints and triggers potent inflammatory responses. Current treatments focus on alleviating inflammation and pain using pharmaceutical agents, which can lead to side effects and complications. This has generated interest in non-pharmacological interventions, such as non-invasive vagus nerve stimulation (VNS). In this study, we explored the anti-inflammatory mechanisms of transcutaneous auricular vagus nerve stimulation (taVNS) in a mouse model of acute gout. Gouty inflammation was induced by injecting monosodium urate (MSU) crystals into the ankle joints of BALB/c mice. The effects of taVNS on the expression of inflammatory cytokines and chemokines in the ankle joint tissue were assessed using real-time quantitative PCR (qPCR), western blotting, histological assessments (H&E staining), and immunohistochemistry (IHC). The role of α7 nicotinic acetylcholine receptors (α7nAChR) was also evaluated by signal blocking. Our findings revealed that MSU significantly elevated gout-associated inflammatory cascades and mediators in the ankle joint. Notably, taVNS at 200 µA and 25 Hz effectively reduced these inflammatory responses, decreasing neutrophil infiltration and chemoattraction within the tissue. taVNS showed significant anti-inflammatory properties by suppressing neutrophil activity, offering a novel therapeutic approach for gout beyond conventional pharmacological methods. Additionally, taVNS holds potential for managing various chronic joint diseases. These results highlight taVNS as a promising non-pharmacological therapy for chronic inflammation. [ABSTRACT FROM AUTHOR]

Background: Common forms of pathological crystals are uric acid or urates, which are responsible for gout, urolithiasis, and other conditions. Methods: We used a kinetic–turbidimetric crystallization assay to evaluate the effect of ten specific methylxanthines on the crystallization of monosodium urate, potassium urate, and ammonium urate in conditions that mimicked urine. We also studied the effect of different levels of 7-methylxanthine in the presence of other biological compounds (albumin and hyaluronic acid) on the solubility of monosodium urate in conditions that mimicked synovial fluid. Results: The results showed that 7-methylxanthine in the range of 16.61–49.84 mg/L inhibited the crystallization of each urate when the initial urate concentration was 3 × 10−3 M (500 mg/L) and the conditions mimicked urine, and that the greatest inhibitory effect was for monosodium urate. In addition, 7-methylxanthine at a concentration of 25 mg/L totally prevented the crystallization of monosodium urate at an initial urate concentration of 2.38 × 10−3 M (400 mg/L) in conditions that mimicked synovial fluid. Moreover, at a low concentration of 7-methylxanthine, albumin and hyaluronic acid increased this inhibitory effect. Conclusions: Our in vitro results demonstrate that 7-methylxanthine inhibits the crystallization of urates in conditions that mimic synovial fluid and urine. [ABSTRACT FROM AUTHOR]

Abstract Gouty inflammation, caused by uric acid crystal deposition, primarily affects tissues around the toe joints and triggers potent inflammatory responses. Current treatments focus on alleviating inflammation and pain using pharmaceutical agents, which can lead to side effects and complications. This has generated interest in non-pharmacological interventions, such as non-invasive vagus nerve stimulation (VNS). In this study, we explored the anti-inflammatory mechanisms of transcutaneous auricular vagus nerve stimulation (taVNS) in a mouse model of acute gout. Gouty inflammation was induced by injecting monosodium urate (MSU) crystals into the ankle joints of BALB/c mice. The effects of taVNS on the expression of inflammatory cytokines and chemokines in the ankle joint tissue were assessed using real-time quantitative PCR (qPCR), western blotting, histological assessments (H&E staining), and immunohistochemistry (IHC). The role of α7 nicotinic acetylcholine receptors (α7nAChR) was also evaluated by signal blocking. Our findings revealed that MSU significantly elevated gout-associated inflammatory cascades and mediators in the ankle joint. Notably, taVNS at 200 µA and 25 Hz effectively reduced these inflammatory responses, decreasing neutrophil infiltration and chemoattraction within the tissue. taVNS showed significant anti-inflammatory properties by suppressing neutrophil activity, offering a novel therapeutic approach for gout beyond conventional pharmacological methods. Additionally, taVNS holds potential for managing various chronic joint diseases. These results highlight taVNS as a promising non-pharmacological therapy for chronic inflammation.

The aim of this study was to validate the preventive effects of koumine (KM), a monoterpene indole alkaloid, on gouty arthritis (GA) and to explore its possible mechanisms. C57BL/6 mice were intraperitoneally administered KM (0.8, 2.4 or 7.2 mg/kg), colchicine (3.0 mg/kg) or sterile saline. One hour later, a monosodium urate (MSU) suspension was injected into the right hind paws of the mice to establish an acute gout model. Inflammation symptoms were evaluated at 0, 3, 6, 12 and 24 h, and the mechanical withdrawal threshold was evaluated at 0, 6 and 24 h. After 24 h, the mice were euthanized, and the joint tissue, kidney and blood were collected for subsequent experiments. Histological examination and antioxidant enzyme, kidney index and serum uric acid (UA) measurements were taken. The expression levels of the signalling pathway components were determined. KM effectively alleviated the symptoms of redness, swelling and pain; counteracted inflammatory cell infiltration; and increased antioxidant enzyme levels, reduced kidney index and serum UA levels through regulating UA excretion in MSU‐induced mice. The expression of toll‐like receptor 4 (TLR4)/nuclear factor kappa‐B (NF‐κB)/nucleotide‐binding oligomerization domain, leucine‐rich repeat and pyrin domain‐containing 3 (NLRP3) signalling pathway proteins and mRNA were reduced in the KM group. These results suggest that KM may be effective in alleviating GA through the TLR4/NF‐κB/NLRP3 pathway. [ABSTRACT FROM AUTHOR]

Purpose of Review: To highlight novel findings in the detection of monosodium urate deposits in vessels using dual energy computed tomography, and to discuss the potential clinical implications for gout and hyperuricemia patients. Recent Findings: Gout is an independent risk factor for cardiovascular disease. However, classical risk calculators do not take into account these hazards, and parameters to identify patients at risk are lacking. Monosodium urate measured by dual energy computed tomography is a well-established technology for the detection and quantification of monosodium urate deposits in peripheral joints and tendons. Recent findings also suggest its applicability to identify vascular urate deposits. Summary: Dual energy computed tomography is a promising tool for detection of cardiovascular monosodium urate deposits in gout patients, to better delineate individuals at increased risk for cardiovascular disease. [ABSTRACT FROM AUTHOR]

Objective: The pleiotropic effect of hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) is responsible for potent defense against inflammatory response. This study evaluated the inhibitory effects of HMG-CoA reductase inhibitors on the monosodium urate (MSU)-induced inflammatory response through the regulation of interleukin-37 (IL-37) expression. Methods: Serum was collected from patients with gout (n = 40) and from healthy controls (n = 30). The mRNA and protein expression of the target molecules IL-1β, IL-37, caspase-1, and Smad3 were measured in THP-1 macrophages stimulated with MSU, atorvastatin, or rosuvastatin using a real-time quantitative polymerase chain reaction and Western blot assay. Transfection with IL-1β or Smad3 siRNA in THP-1 macrophages was used to verify the pharmaceutical effect of statins in uric-acid-induced inflammation. Results: Serum IL-37 levels in gout patients were significantly higher than in controls (p < 0.001) and was associated with the serum uric acid level (r = 0.382, p = 0.008). THP-1 cells stimulated with MSU markedly induced IL-37 mRNA expression and the transition of IL-37 from the cytoplasm to the nucleus. Recombinant IL-37 treatment dose-dependently inhibited activation of caspase-1 and IL-1β in MSU-induced inflammation. Atorvastatin and rosuvastatin attenuated caspase-1 activation and mature IL-1β expression but augmented translocation of IL-37 from the cytoplasm to the nucleus. Atorvastatin and rosuvastatin induced phosphorylation of Smad3 in THP-1 cells treated with MSU crystals. Statins potently attenuated translocation of IL-37 from the cytoplasm to the nucleus in THP-1 macrophages transfected with Smad3 siRNA compared to cells with negative control siRNA. Conclusions: This study revealed that statins inhibit the MSU-induced inflammatory response through phosphorylated Smad3-mediated IL-37 expression in THP-1 macrophages. [ABSTRACT FROM AUTHOR]

Gout arthritis is an inflammatory arthritis characterized by increased serum uric acid and accumulation of monosodium urate (MSU) crystals in soft tissues. The treatment for gout arthritis is centered on reducing uric acid agents with long-term and anti-inflammatory agents during attack times. In recent studies, it is noteworthy that Indomethacin and Dexamethasone have positive effects in the treatment of gout. Dimethyl sulfoxide (DMSO) is a lipophilic solvent and has an anti-inflammatory effect at appropriate doses. Based on this information, for this study, the effects of these three agents were investigated in rats using a gut model to compare their efficacy. In the study, a total of 48 female 3–4-month rats were divided equally into 8 groups: Control, Indomethacin, DMSO, Dexamethasone, Gout, Gout+Indomethacin, Gout+DMSO, Gout +Dexamethasone. During the eight-week study, a gout arthritis model was used that included 10 mg MSU given intra-articularly in the right foot. Indomethacin 12.5 mg/kg intragastric, DMSO 0.1 ml intraperitoneally and dexamethasone 0.2 mg/kg were administered subcutaneously to the related groups once a day for seven days. At the end of the study, collected articular tissues were stained with haematoxylin and eosin after the fixation and decalcification processes were done. The findings obtained showed that inflammation was reduced in treatment groups compared to the Control groups (all p values 0.002). Also, synovial proliferation was remarkably decreased in the Gout+Dexamethasone group compared to the Gout group (p = 0.019). As a result of these findings, although the three agents all reduced inflammation in gout arthritis, DMSO was shown to be more advantageous due to its having fewer side-effects. [ABSTRACT FROM AUTHOR]

The use of ultrasonography (US) has considerable potential for the diagnosis and monitoring of gout due to its capacity to detect monosodium urate deposits. In the last decade, a critical amount of scientific data has become available. Consensus-based definitions for ultrasonographic elementary lesions in gout have been developed, tested, and validated, as well as a semiquantitative scoring system for their quantification. Many scanning protocols have been proposed in different clinical scenarios. In this review, we formulate a set of practical suggestions for the use of the US in daily practice. We discuss the current knowledge to indicate which joints and structures are to be scanned and which elementary findings are to be evaluated according to the clinical scenario. While for some clinical settings, a quite definite scanning protocol can be indicated, others still need to be further investigated, and how to obtain the best out of the US is still entrusted to the individual experience. [ABSTRACT FROM AUTHOR]

Background: Spinal gout, a rare and often underdiagnosed condition, significantly impacts patients’ quality of life. Therefore, the aim of the research is to analyze cases of spinal gout, including clinical features, anatomical location of spinal gout, laboratory studies, imaging studies, treatment choices, and outcomes from various cases of spinal gout. Methods: The author conducted a systematic literature search in the PUBMED and Science Direct databases from 2013 to 2023. We included clinical case presentations of spinal cases in adults, published in English. The three researchers independently reviewed the title and abstract of each article, and any differences in opinions were resolved through consensus. The extracted data were subsequently analyzed descriptively. Results: A total of 88 cases of spinal gout were obtained and studied. Out of the total reviewed cases of spinal gout, 89.77% of the subjects were male, with an average age of 51.9 years (age range 16–87 years). Common symptoms include back/neck pain (78.41%) and lower extremity weakness (37.50%). The lumbar spine is the most frequently affected region (62.50%), diagnosed primarily through magnetic resonance imaging (MRI) scans. Surgery, performed in 61.36% of cases, commonly involves decompressive laminectomy. Posttreatment, symptoms resolve in 87.50% of cases. Conclusion: Cases of spinal gout present with a variety of symptoms, including back pain and weakness. Diagnosis typically involves an MRI examination and synovial fluid analysis for confirmation. Treatment varies and includes medication therapy and surgical interventions. A deeper understanding of these cases can assist healthcare practitioners in the management and diagnosis of spinal gout cases.

Gout is an inflammatory arthropathy resulting from the deposition of monosodium urate crystals in and around joints, triggering the release of pro-inflammatory cytokines. Some of the key principles for managing gout are encompassing comorbidity screening, gout flare treatment, urate-lowering therapy, and anti-inflammatory prophylaxis. One of the major concerns with gout treatment is the side effects of drug due to uncontrolled biodistribution. Nanocarrier systems are utilized to surmount the limitations of current drugs, including not only biodistribution issues but also the stability and bioavailability of the drugs. Nanocarriers as promising drug delivery systems can effectively deliver drugs by specifically targeting inflamed tissues through enhanced permeability and retention effect mediated delivery. Notable examples include liposomes, niosomes, ethosomes, transfersomes, solid lipid nanoparticles, polymeric nanoparticles, nanoemulsions, and liquid crystalline nanoparticles, namely, cubosomes, hexosomes, and spongosomes. These nanocarriers hold great promise as vehicles for transporting poorly therapeutic agents to precise target sites, associated with controlled release capabilities to bolster bioavailability. Preclinical studies have demonstrated the efficacy of nanocarrier-based therapies in reducing inflammation by specifically targeting inflamed tissues, inhibiting urate crystal formation, and improving joint function in animal models of gout. In this review, we explore the main nanocarrier systems, including their respective advantages and drawbacks, and emphasize their role in nanoformulations for advancing gout treatment. The encapsulation of active agents within nanocarriers for gout therapy represents a significant advancement in the pharmaceutical area and nanomedicine application to succeed in the overall context of gout treatment in the near future. [ABSTRACT FROM AUTHOR]

Pyroptosis is a programmed cell death process that frequently occurs in many diseases, including hyperuricemic nephropathy (HN). In HN, a range of stimuli mediates inflammation, leading to the activation of inflammasomes and the production of gasdermin D (GSDMD). Baicalin (BA), a natural flavonoid renowned for its antioxidant and anti‐inflammatory properties, was investigated for its role in HN in this study. Initially, HN‐like inflammation and pyroptosis were induced in HK‐2 cells with treatment of monosodium urate (MSU), followed by the BA treatment. The expression of pyroptosis‐associated genes, Panx‐1 and P2X7, at both mRNA and protein levels was assessed through real‐time polymerase chain reaction (RT‐qPCR) and Western blotting (WB) without or with BA treatment. The results showed that expression of Panx‐1 and P2X7 at mRNA and protein levels was increased in MSU‐treated HK‐2 cells, which subsequently decreased upon the BA treatment. Further experiments showed that BA could combine NLRP3 inflammasome and GSDMD, destabilizing GSDMD protein. Moreover, BA protected the cell membrane from MSU‐induced damage, as evidenced by Hoechst 33342 and PI double staining, lactate dehydrogenase (LDH) assays, and electron microscopy observations. These results suggest that BA is involved in the regulating Panx‐1/P2X7 pathways and thus inhibits pyroptosis, highlighting its potential therapeutic effect for HN. [ABSTRACT FROM AUTHOR]

Background: Spinal gout, a rare and often underdiagnosed condition, significantly impacts patients' quality of life. Therefore, the aim of the research is to analyze cases of spinal gout, including clinical features, anatomical location of spinal gout, laboratory studies, imaging studies, treatment choices, and outcomes from various cases of spinal gout. Methods: The author conducted a systematic literature search in the PUBMED and Science Direct databases from 2013 to 2023. We included clinical case presentations of spinal cases in adults, published in English. The three researchers independently reviewed the title and abstract of each article, and any differences in opinions were resolved through consensus. The extracted data were subsequently analyzed descriptively. Results: A total of 88 cases of spinal gout were obtained and studied. Out of the total reviewed cases of spinal gout, 89.77% of the subjects were male, with an average age of 51.9 years (age range 16-87 years). Common symptoms include back/neck pain (78.41%) and lower extremity weakness (37.50%). The lumbar spine is the most frequently affected region (62.50%), diagnosed primarily through magnetic resonance imaging (MRI) scans. Surgery, performed in 61.36% of cases, commonly involves decompressive laminectomy. Posttreatment, symptoms resolve in 87.50% of cases. Conclusion: Cases of spinal gout present with a variety of symptoms, including back pain and weakness. Diagnosis typically involves an MRI examination and synovial fluid analysis for confirmation. Treatment varies and includes medication therapy and surgical interventions. A deeper understanding of these cases can assist healthcare practitioners in the management and diagnosis of spinal gout cases. [ABSTRACT FROM AUTHOR]

Background: Ultrasound (US) has a high sensitivity in detecting monosodium urate (MSU) deposition in gout patients. However, the value of US in predicting gout flares has been reported only in a few monocentric studies. Objective: To investigate the association between gout flares in the previous year and US-detected MSU burden using two different US scores. Design: A retrospective study. Methods: Patients with gout were consecutively recruited to undergo musculoskeletal US examinations of their knees, ankles, and feet. The score derived from Outcome Measure in Rheumatology (hereinafter referred to as MSU score) and musculoskeletal US features-based (hereinafter referred to as MSKF score) were used to quantify the MSU burden of gout. Odds ratios for frequent gout flares were calculated. Results: We enrolled 1894 patients with gout (mean age: 45 years; gout duration: 5 years; males: 96.1%), experiencing a median of three flares over the past year. Of these, 428 (22.6%) patients reported frequent (⩾7) gout flares. The MSU and MSKF median scores were 6 and 9, respectively. For each five-point increase in MSU and MSKF score, the odds ratio of frequent gout flares increased 1.13-fold and 1.24-fold, respectively. The area under the curve (AUC) for the MSU and MSKF score was 0.635 [95% confidence interval (CI): 0.604–0.665] and 0.688 (95% CI: 0.659–0.718), respectively, (AUC difference 0.054, p value for AUC difference < 0.001). Conclusion: The MSU and MSKF scores were significantly associated with the number of gout flares in the previous year. The MSKF score outperformed the MSU score in terms of frequent gout flare discrimination. [ABSTRACT FROM AUTHOR]

Objective: To study the differential gene expression and immune cell infiltration of gout patients, to find the key genes and immune cells of gout pathogenesis, and to explore the relationship between immune cells and gout. Methods: The gout chip GSE160170 was downloaded from the GEO database, and the differential gene expression analysis was carried out with the help of R language. Then, the STRING database was used to analyze the differential gene, and the Cytoscape software was used to screen the key genes, and then carry out enrichment analysis. At the same time, the infiltration of immune cells were analyzed. Results: The study found that IL-6, IL-1β, TNF, CCL3, CXCL8 and CXCL1 were key genes in the pathogenesis of gout, which were mainly exerted by IL-17, Toll-like receptor, NOD-like receptor, NF-κB and other signaling pathways. Processes such as cellular responses to lipo-polysaccharides, bacteria-derived molecules, and biological stimuli lead to disease; immune infiltration results indicate that memory B cells, activated NK cells, activated dendritic cells, activated mast cells and eosinophils were involved in the disease. It was significantly expressed in gout patients; the correlation analysis between immune cells showed that the expression of follicular helper T cells were positively correlated with the expression of activated mast cells, and the expression of unactivated NK cells and monocyte were negatively correlated. Conclusion: Key genes and differentially expressed immune cells are closely related to the pathogenesis of gout, providing new ideas for the study of the molecular mechanism of gout. [ABSTRACT FROM AUTHOR]

Key Clinical Message Hyperuricemic patients (≥7.8 mg/dL) can develop polyarticular tophaceous gout from intermittent arthritis if untreated. Acute flares and tophi development can be avoided by lowering blood urate levels with xanthine oxidase inhibitors.

Key Clinical Message: Hyperuricemic patients (≥7.8 mg/dL) can develop polyarticular tophaceous gout from intermittent arthritis if untreated. Acute flares and tophi development can be avoided by lowering blood urate levels with xanthine oxidase inhibitors. [ABSTRACT FROM AUTHOR]

Background: Since NEK7 is critical for NLRP3 inflammasome activation, NEK7 inhibitors could be employed as therapeutic agents against gout, a representative disease caused by NLRP3 inflammasome. Methods: We designed NEK7 inhibitors based on biochemical kinome profiling of 2,7-substituted thieno[3,2-d]pyrimidine derivatives (SLC3031~3035 and SLC3037). Inflammasome activation was assessed by ELISA of IL-1b and immunoblotting of IL-1b maturation after treatment of bone marrow-derived macrophages with LPS+monosodium urate (MSU). NLPR3 binding to NEK7 and oligomerization were examined using immunoprecipitation and Blue Native gel electrophoresis, respectively. In vivo effect was investigated by studying gross and histopathological changes of food pad tissue of MSU-injected mice, together with assays of maturation of IL-1b and ASC speck in the tissue. Results: SLC3037 inhibited inflammasome by MSU and other inflammasome activators through blockade of NLRP3 binding to NEK7 or oligomerization, and subsequent ASC oligomerization/phosphorylation. SLC3037 significantly reduced foot pad thickness and inflammation by MSU, which was superior to the effects of colchicine. SLC3037 significantly reduced content or maturation of IL-1b and ASC speck in the food pad. The number and height of intestinal villi were decreased by colchicine but not by SLC3037. Conclusion: SLC3037, a NLRP3 inhibitor blocking NEK7 binding to NLRP3, could be a novel agent against diseases associated with NLRP3 inflammasome activation such as gout, cardiovascular diseases, metabolic syndrome or neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

The increased utilization of titanium dioxide (TiO2) nanoparticles (TNPs) in various industrial and consumer products has raised concerns regarding its harmful effect due to its accumulation within the different systems of the human body. Here, we focused on the influence of TNPs on the growth and aggregation of two crucial crystalline substances, calcium phosphate (CaP) and monosodium urate (MSU), particularly its implications in gout disease. In this study, we adopted microscopic techniques and generated kinetic models to examine the interactions between TNPs, CaP and MSU, and crystallization, under controlled laboratory conditions. Our findings reveal that TNPs not only facilitate the growth of these crystals but also promote their co-aggregations. Crystal dissolution kinetics also exhibit that an increase in TNPs concentration corresponds to a reduction in the dissolution rate of CaP and MSU crystals in presence of the dissoluting agent hydroxycitrate (Hcit). These observations suggest that TNPs can stabilize CaP+MSU mixed crystals, which underscores the significance of TNPs' exposure in the pathogenesis of gout disease. [ABSTRACT FROM AUTHOR]

Gout is characterized by the formation of monosodium urate crystals in peripheral joints. We carried out laboratory studies to investigate the effect of adding nine different methylxanthines and two different methylated uric acid derivatives on the development of these crystals over the course of 96 h in a medium whose composition was similar to that of synovial fluid. Our results showed that 7-methylxanthine reduced or totally prevented crystal formation; 1-methylxanthine, 3-methylxanthine, 7-methyluric acid, and 1,3-dimethyluric acid had weaker effects, and the other molecules had no apparent effect. The presented results indicate that a 7-methylxanthine concentration of about 6 × 10−5 M (10 mg/L) prevented the formation of crystals for an initial urate concentration of 1.78 × 10−3 M (300 mg/L) in the presence of 0.4 M of Na+ for 96 h at 25 °C and a pH of 7.4. We attribute these results to alterations in thermodynamics, not kinetics. Our results suggest that prevention of crystallization in vivo could be achieved by direct oral administration of 7-methylxanthine or other methylxanthines that are metabolized to 7-methylxanthine. For example, the hepatic metabolism of theobromine leads to significant plasma levels of 7-methylxanthine (14% of the initial theobromine concentration) and 3-methylxanthine (6% of the initial theobromine concentration); however, 7-methyluric acid is present at very low concentrations in the plasma. It is important to consider that several of the specific molecules we examined (theobromine, caffeine, theophylline, dyphylline, etophylline, and pentoxifylline) did not directly affect crystallization. [ABSTRACT FROM AUTHOR]

Background: Although bee venom (BV) has clinical benefits in osteoarthritis and rheumatoid arthritis, it has not been tested as treatment for gouty arthritis. Moreover, in vitro, BV has been proven to exhibit anti-inflammatory and positive effects on osteoarthritis, but only limited evidence can confirm its beneficial effects on gout. Thus, this study aims to assess the anti-inflammatory effects of BV on monosodium urate (MSU)-induced THP-1 monocytes. Methods: THP-1 monocytes were differentiated into mature macrophages using phorbol 12-myristate 13-acetate (PMA) and pretreated for 6 hours with BV and a Caspase-1 inhibitor in a physiologically achievable range of concentrations (BV, 0.1–1 μg/mL; Caspase-1 inhibitor, 1–10 μM), followed by MSU crystal stimulation for 24 hours. The secretions of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), IL-6, IL-8, cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and nitric oxide (NO) were increased in the MSU crystal-stimulated THP-1 cells. Results: Caspase-1 inhibitors suppressed the production of all mediators in a dose-dependent manner. BV worked on equal terms with Caspase-1 inhibitors and showed more satisfactory effects on TNF-α, PGE2, COX-2, and inducible nitric oxide synthase (iNOS). Moreover, the western blot analysis revealed that BV regulated the transcriptional levels of these mediators via the suppression of extracellular signal-regulated kinase (ERK) pathway activation. Conclusion: The results of the present study clearly suggest that BV inhibits MSU-induced inflammation in vitro, suggesting a possible role for BV in gout treatment.

Abstract Background Serum uric acid levels are higher in patients with type 2 diabetes and prediabetes compared to healthy individuals, and hyperuricemia causes a significant rate of complications and mortality through heart and kidney diseases. Accordingly, the present systematic review and meta-analysis aimed to investigate the effect of empagliflozin on serum uric acid levels. Materials and methods Electronic databases, including PubMed, Scopus, Web of Science, Cochrane, and Google Scholar, were used to search papers until May 22, 2023. Data analysis was conducted by STATA Version 14, and P-value

Objective: To validate the gout analyzer as a clinical method of synovial fluid crystal analysis. Methods: Thirty knee synovial fluid samples with suspected calcium pyrophosphate (CPP) crystals were analyzed. Within 48 hours after collection, each non-centrifuged sample was examined blindly and independently by one or more rheumatologists in the following order: 1) with an optical microscope under ordinary light, 2) with the same microscope under compensated polarization provided by a gout analyzer, and 3) with a fully equipped compensated polarized microscope with a rotating stage as the gold standard. As a reference, laboratory technicians analyzed fresh, centrifuged synovial fluid using a gout analyzer. Results: Of the 30 samples analyzed, CPP and monosodium urate (MSU) crystals were detected in 11 and four, non-centrifuged samples, respectively, using a fully equipped compensated polarized microscope. The rheumatologists' detection rate of crystals in the non-centrifuged synovial fluid under ordinary light and with a gout analyzer was 73.3% and 80%, respectively. The laboratory technicians' detection rate in fresh centrifuged synovial fluid using a gout analyzer was 100%. Conclusion: A gout analyzer may be used to diagnose gout and calcium pyrophosphate deposition disease definitively if a fully equipped compensated polarized microscope is unavailable. [ABSTRACT FROM AUTHOR]

Background: Common forms of pathological crystals are uric acid or urates, which are responsible for gout, urolithiasis, and other conditions. Methods: We used a kinetic–turbidimetric crystallization assay to evaluate the effect of ten specific methylxanthines on the crystallization of monosodium urate, potassium urate, and ammonium urate in conditions that mimicked urine. We also studied the effect of different levels of 7-methylxanthine in the presence of other biological compounds (albumin and hyaluronic acid) on the solubility of monosodium urate in conditions that mimicked synovial fluid. Results: The results showed that 7-methylxanthine in the range of 16.61–49.84 mg/L inhibited the crystallization of each urate when the initial urate concentration was 3 × 10−3 M (500 mg/L) and the conditions mimicked urine, and that the greatest inhibitory effect was for monosodium urate. In addition, 7-methylxanthine at a concentration of 25 mg/L totally prevented the crystallization of monosodium urate at an initial urate concentration of 2.38 × 10−3 M (400 mg/L) in conditions that mimicked synovial fluid. Moreover, at a low concentration of 7-methylxanthine, albumin and hyaluronic acid increased this inhibitory effect. Conclusions: Our in vitro results demonstrate that 7-methylxanthine inhibits the crystallization of urates in conditions that mimic synovial fluid and urine.

Objective: The pleiotropic effect of hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) is responsible for potent defense against inflammatory response. This study evaluated the inhibitory effects of HMG-CoA reductase inhibitors on the monosodium urate (MSU)-induced inflammatory response through the regulation of interleukin-37 (IL-37) expression. Methods: Serum was collected from patients with gout (n = 40) and from healthy controls (n = 30). The mRNA and protein expression of the target molecules IL-1β, IL-37, caspase-1, and Smad3 were measured in THP-1 macrophages stimulated with MSU, atorvastatin, or rosuvastatin using a real-time quantitative polymerase chain reaction and Western blot assay. Transfection with IL-1β or Smad3 siRNA in THP-1 macrophages was used to verify the pharmaceutical effect of statins in uric-acid-induced inflammation. Results: Serum IL-37 levels in gout patients were significantly higher than in controls (p < 0.001) and was associated with the serum uric acid level (r = 0.382, p = 0.008). THP-1 cells stimulated with MSU markedly induced IL-37 mRNA expression and the transition of IL-37 from the cytoplasm to the nucleus. Recombinant IL-37 treatment dose-dependently inhibited activation of caspase-1 and IL-1β in MSU-induced inflammation. Atorvastatin and rosuvastatin attenuated caspase-1 activation and mature IL-1β expression but augmented translocation of IL-37 from the cytoplasm to the nucleus. Atorvastatin and rosuvastatin induced phosphorylation of Smad3 in THP-1 cells treated with MSU crystals. Statins potently attenuated translocation of IL-37 from the cytoplasm to the nucleus in THP-1 macrophages transfected with Smad3 siRNA compared to cells with negative control siRNA. Conclusions: This study revealed that statins inhibit the MSU-induced inflammatory response through phosphorylated Smad3-mediated IL-37 expression in THP-1 macrophages.

Background: Persistent hyperuricemia can lead to the generation and deposition of monosodium urate (MSU) crystals. This can trigger gouty arthritis (GA), which in turn induces inflammation. Activation of the Nod-like receptor pyrin domain containing 3 (NLRP3) inflammasome plays a critical role in the onset and progression of GA. Autophagy may have a dual effect on GA with regard to the NLRP3 inflammasome. Therefore, the present study aimed to gain a deeper comprehension of the interaction between autophagy and NLRP3 inflammasome activation is imperative for developing more efficacious treatments for GA. Methods: Peripheral blood monocytes (PBMCs) were first isolated from GA patients and healthy controls and underwent bulk RNA sequencing analysis. Overexpression and knockdown of dual specificity phosphatase 1 (DUSP1) was performed in THP-1 monocytes to investigate its role in the immune response and mitochondrial damage. The luciferase assay and Western blot analysis were used to study the interaction between autophagy and NLRP3 inflammasome activation. Results: Bulk RNA sequencing analysis showed significant upregulation of DUSP1 expression in PBMCs from GA patients compared to healthy controls. This result was subsequently verified by reverse transcription quantitative polymerase chain reaction (RT-qPCR). DUSP1 expression in human THP-1 monocytes was also shown to increase after MSU treatment. Downregulation of DUSP1 expression increased the secretion of inflammatory cytokines after MSU treatment, whereas the overexpression of DUSP1 decreased the secretion levels. Lipopolysaccharides (LPS) combined with adenosine-triphosphate (ATP) led to mitochondrial damage, which was rescued by overexpressing DUSP1. DUSP1 overexpression further increased the level of autophagy following MSU treatment, whereas downregulation of DUSP1 decreased autophagy. Treatment with the autophagy inhibitor 3-Methyladenine (3-MA) restored inflammatory cytokine secretion levels in the DUSP1 overexpression group. MSU caused pronounced pathological ankle swelling in vivo. However, DUSP1 overexpression significantly mitigated this phenotype, accompanied by significant downregulation of inflammatory cytokine secretion levels in the joint tissues. Conclusions: This study revealed a novel function and mechanism for DUSP1 in promoting autophagy to mitigate the MSU-induced immune response in GA. This finding suggests potential diagnostic biomarkers and anti-inflammatory targets for more effective GA therapy.

Osteoarthritis (OA) is one of the leading causes of disability worldwide. As our understanding of OA progressively has moved from a purely mechanical "wear and tear" concept toward a complex multi-tissue condition in which inflammation plays a central role, the possible role of crystal-induced inflammation in OA incidence and progression may be relevant. In addition to gout, which affects 4% of the US population, basic calcium phosphate and calcium pyrophosphate deposition both may induce joint inflammation and may play a role in pain in OA. This narrative review article discusses the possible mechanisms underlying the associations between crystal-induced arthropathies and OA, and the important implications of these for clinical practice and future research. [ABSTRACT FROM AUTHOR]

Objective To observe the damage of MSU (monosodium-urate) on osteoblasts and the mechanism and therapeutic effect of SFN (sulforaphane) on osteoblasts induced by MSU. Methods CCK-8 kit was used to detect osteoblast viability. Flow cytometry was used to detect the apoptosis. ROS levels were confirmed using ROS sensitive fluorescent probe. Drug concentration and duration of action were determined after MSU (10, 50, 100, 300, 500 μg/mL) and SFN (1, 5, 10, 20, 50 μmol/L) were added respectively in osteoblasts culture medium for 0, 12, 24, 48, 72 h. Nrf2, HO-1, HIF-1, IL-6, and caspsae-3 in osteoblasts were detected using Western blotting. Results The toxic effect of MSU on osteoblasts activity increased along with the increase of concentration and time. Cell viability was less than 50% when the concentration was 300 μg/mL and reaction time exceeded 48 hours. There was no effect on osteoblast viability when SFN was at 1 μmol/L and 10 μmol/L, but cell viability reduced when SFN was at 20 μmol/L and 50 μmol/L. 300 μg/mL and 10 μmol/L were determined as action concentrations of MSU and SFN, respectively. 48 h was determined as action time. MSU increased the level of ROS in osteoblasts, while SFN decreased the ROS level and apoptosis rate in osteoblasts increased by MSU. SFN reduced the expression levels of HIF-1, IL-6, and caspase-3 in MSU induced osteoblasts, but increased the expression levels of Nrf2 and HO-1. Conclusion SFN reduces osteoblast damage induced by MSU. [ABSTRACT FROM AUTHOR]

Background: Serum uric acid levels are higher in patients with type 2 diabetes and prediabetes compared to healthy individuals, and hyperuricemia causes a significant rate of complications and mortality through heart and kidney diseases. Accordingly, the present systematic review and meta-analysis aimed to investigate the effect of empagliflozin on serum uric acid levels. Materials and methods: Electronic databases, including PubMed, Scopus, Web of Science, Cochrane, and Google Scholar, were used to search papers until May 22, 2023. Data analysis was conducted by STATA Version 14, and P-value < 0.05 were considered statistically significant. Results: The results obtained from the combination of 12 studies with 7801 samples of diabetic patients indicated that in the empagliflozin group, the serum uric acid levels of the patients decreased ([standardized mean difference (SMD): − 1.97 (95%CI − 3.39, − 0.55)], Systolic blood pressure (SBP) [SMD: − 2.62 (95%CI − 3.87, − 1.37)] and diastolic blood pressure (DBP) [SMD: − 0.49 (95%CI − 0.68, − 0.29)]). On the other side, empagliflozin treatment did not affect the patients' HbA1c levels ([SMD: − 2.85 (95%CI − 6.14, 0.45)], eGFR [SMD: 0.78 (95%CI − 0.63, 2.18)], creatinine [SMD:0.11 (95%CI − 0.10, 0.31)], LDL [SMD: 0.14 (95%CI − 0.43, 0.71)], and HDL [SMD:1.38 (95%CI − 0.22, 2.99)]). Compared with the placebo, empagliflozin was more effective in reducing the uric acid levels ([SMD: − 1.34 (95%CI − 2.05, − 0.63)], SBP [SMD: − 2.11 (95%CI − 3.89, − 0.33)], and HbA1c [SMD: − 1.04 (95%CI − 1.95, − 0.13)]). Moreover, compared with sitagliptin also, empagliflozin was more effective in reducing uric acid levels ([SMD: − 1 (95%CI − 1.78, − 0.22)], and creatinine [SMD: − 1.60 (95%CI − 2.28, − 0.92)]) and increasing eGFR levels [SMD: 0.99 (95%CI: 0.37, 1.62)] of the patients. Compared with dapagliflozin also, empagliflozin caused a reduction in eGFR level [SMD: − 0.45 (95%CI − 0.82, − 0.08)]. Conclusion: Empagliflozin treatment was effective in controlling diabetic patients' hyperuricemia and hypertension. [ABSTRACT FROM AUTHOR]

Cardiovascular disease in gout is a central issue, but the underlying mechanisms linking the two are unclear. The existence of monosodium (MSU) crystal deposition directly inflaming vessel walls has been recurrently suggested and challenged since the 1950s and is again a matter of active debate since recent studies using dual-energy computed tomography (DECT) suggested a higher prevalence of plaques considered to be containing MSU crystals in patients with gout. The objective of this review is to critically cover the evidence gathered on MSU crystal deposition in the cardiovascular system. In patients affected with gout, histological evidence of MSU crystals in arteries lacks a biochemical characterization supporting the observation in polarized light microscopy, while current knowledge on vascular lesions identified in DECT as containing MSU crystals suggests that they may be only artifacts, including in cadaveric and phantom studies. In individuals without gout, MSU crystal deposition in vessel walls have not been demonstrated, despite higher urate local plaque concentrations and increased xanthine oxidase activity. Gout is associated with increased arterial calcification and atherosclerosis, both being potential confounders of suspected MSU crystal deposition for the analysis of DECT scans and histopathology, respectively. In summary, the reality of the presence of MSU crystals in vascular plaques has not been demonstrated so far, and needs further investigation as it represents a potential outcome for cardiovascular complications of gout. [ABSTRACT FROM AUTHOR]

Aim: Inflammation and apoptosis are main pathological processes that lead to the development of hyperuricemic nephropathy (HN). This study aims to explore whether baicalin (BA) and baicalein (BAI) can relieve the damage through PI3K/AKT/NF-κB signal pathway and provide more reliable and precise evidence for the treatment of HN. Methods: HN mice were induced by yeast extract with potassium oxonate (PO), and HK-2 cells were induced by monosodium urate (MSU). Molecular docking, western blot, q-PCR, and other methods were used to explore the changes of various indicators in HN mice and HK-2 cells. Results: Molecular docking results showed that BA and BAI had good binding ability with PI3K, AKT, p65 and IκBα. BA and BAI significantly ameliorated the levels of renal function, decreased the p-PI3K, p-AKT and p-p65 expression, down-regulated the BAX/BCL2 and CASP3, and blunted the mRNA levels of tumour necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-18 in both renal tissue of HN mice and HK-2 cells induced by MSU. BA and BAI also decreased the oxidative stress level of MSU-induced HK-2 cells. Conclusion: BA and BAI were confirmed to attenuate HN through alleviating renal inflammatory and apoptosis in cells and tissues by inhibiting PI3K/AKT/NF-κB pathway. BA and BAI were expected to be developed as new anti-HN drugs. [ABSTRACT FROM AUTHOR]

Abstract Introduction Efficient and complete debridement of intra-articular deposits of monosodium urate crystals is rarely achieved by existing arthroscopic tools such as shavers or radiofrequency ablation, while cavitation technology represents a prospective solution for the non-invasive clearance of adhesions at intra-articular interfaces. Methods Simulation modeling was conducted to identify the optimal parameters for the device, including nozzle diameters and jet pressures. Gouty arthritis model was established in twelve rats that were equally and randomly allocated into a cavitation debridement group or a curette debridement group. A direct injection nozzle was designed and then applied on animal model to verify the effect of the cavitation jet device on the removal of crystal deposits. Image analysis was performed to evaluate the clearance efficiency of the cavitation device and the pathological features of surrounding tissue were collected in all groups. Results To maximize cavitation with the practical requirements of the operation, an experimental rig was applied, including a 1 mm direct injection nozzle with a jet pressure of 2.0 MPa at a distance of 20 mm and a nitrogen bottle as high-pressure gas source. With regards to feasibility of the device, the clearance rates in the cavitation group were over 97% and were significantly different from the control group. Pathological examination showed that the deposition of monosodium urate crystals was removed completely while preserving the normal structure of the collagen fibers. Conclusions We developed a promising surgical device to efficiently remove intra-articular deposits of monosodium urate crystals. The feasibility and safety profile of the device were also verified in a rat model. Our findings provide a non-invasive method for the intraoperative treatment of refractory gouty arthritis.

Objectives: Gout is an inflammatory arthritis of the joints and soft tissues occurring due to deposition of monosodium urate (MSU) crystals, which are caused by persistent hyperuricemia. Soyeom pharmacopuncture is one treatment method that has been traditionally used for pain management in Oriental medicine. However, studies on its effect in reducing gout pain have been insufficient. Therefore, we selected Soyeom pharmacopuncture among natural products used in Korea as the new target of our study.Methods: The effects of Soyeom pharmacopuncture were examined in mouse models of acute gout induced by injection of MSU crystals into footpads. IL-1β, IL-6, and TNF-α production were examined by immunoblotting and enzyme-linked immunosorbent assay as hallmarks of NLRP3 inflammasome and cytokine activation.Results: Soyeom pharmacopuncture reduced foot edema in gout-induced mice, as well as IL-1β, nitrite, IL-6, and TNF-α production. Moreover, Soyeom pharmacopuncture also reduced MSU-induced gout inflammatory gene expressions, specifically those in the NF-kB pathway.Conclusion: Pharmacopuncture may serve as a new solution for other inflammatory diseases as well. Through active follow-up studies, we could thoroughly understand the clinical value of Soyeom pharmacopuncture.

Gout is an inflammatory arthritis initiated by the deposition of monosodium urate crystals (MSU) around the joints and surrounding tissues. MSU crystals activate the nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome to the release of interleukin-1β (IL-1β). Gout can have a substantial impact on patient's quality of life, and currently available medicines are unable to meet all the clinical needs. This study explored anti-gout potentials of the Rice14 (R14) peptide, a peptide derived from leaves of wild rice Oryza minuta. The effects of R14 peptide on IL-1β secretion in THP-1 macrophages with MSU crystals-induced inflammation were examined. Our results clearly showed that the R14 peptide significantly inhibited the secretion of IL-1β in MSU crystals-induced macrophages, and the effects were dose-related. For safety testing, the R14 peptide did not show both cytotoxicity and hemolytic activity. In addition, the R14 peptide strongly suppressed the phospho-IκB-α and nuclear factor kappa-B (NF-κB) p65 proteins in NF-κB signaling pathway, reduced the NLRP3 expression and inhibited the MSU crystals-mediated cleavage of caspase-1 as well as mature IL-1β. The R14 peptide also reduced MSU-triggered intracellular ROS levels in macrophages. Taken together, these results indicated that R14 peptide inhibited MSU crystals-induced IL-1β production through NF-κB and NLRP3 inflammasome activation. Our findings demonstrated that R14 peptide, the newly recognized peptide from wild rice, possessed potent regulatory activity against IL-1β production in MSU crystals-induced inflammation, and we therefore propose that the R14 peptide is a promising molecule with potential clinical application in the treatment of MSU crystals-induced inflammation. [ABSTRACT FROM AUTHOR]

Peroxisome proliferator-activated receptor γ (PPAR-γ) is thought to negatively regulate NLRP3 inflammasome activation. The aim of this study was to identify the inhibitory effect of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) on monosodium urate (MSU) crystal-induced NLRP3 inflammasome activation through the regulation of PPAR-γ in THP-1 cells. The expression of PPAR-γ, NLRP3, caspase-1, and interleukin-1β (IL-1β) in human monocytic THP-1 cells transfected with PPAR-γ siRNA or not and stimulated with MSU crystals was assessed using quantitative a real time-polymerase chain reaction and Western blotting. The expression of those markers in THP-1 cells pretreated with statins (atorvastatin, simvastatin, and mevastatin) was also evaluated. Intracellular reactive oxygen species (ROS) were measured using H2DCF-DA and flow cytometry analyses. THP-1 cells treated with MSU crystals (0.3 mg/mL) inhibited PARR-γ and increased NLRP3, caspase-1, and IL-1β mRNA and protein expression, and all those changes were significantly reversed by treatment with atorvastatin, simvastatin, or mevastatin. PPAR-γ activity revealed that MSU crystals suppressed PPAR-γ activity, which was markedly augmented by atorvastatin, simvastatin, and mevastatin. Transfecting cells with PPAR-γ siRNA attenuated the inhibitory effect of statins on MSU crystal-mediated NLRP3 inflammasome activation. Statins also significantly reduced the intracellular ROS generation caused by stimulation with MSU crystals. The inhibitory effects of atorvastatin and simvastatin on intracellular ROS generation were reduced in THP-1 cells transfected with PPAR-γ siRNA. This study demonstrates that PPAR-γ is responsible for suppressing MSU-mediated NLRP3 inflammasome activation. The inhibitory effect of statins on MSU-induced NLRP3 inflammasome activation depends on PPAR-γ activity and production and the inhibition of ROS generation. [ABSTRACT FROM AUTHOR]

Histone deacetylase (HDAC) has been found to play a crucial role in the regulation of osteoclast differentiation and formation. This study was designed to identify the effect of the HDAC6 inhibitor CKD-WID on the receptor for the activation of nuclear factor-κB ligand (RANKL)-mediated osteoclast formation in the presence of monosodium urate (MSU) in RAW 264.7 murine macrophage cells. The expression of osteoclast-specific target genes, calcineurin, and nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) was evaluated in RAW 264.7 murine macrophages treated with MSU, RANKL, or CKD-WID by real-time quantitative polymerase chain reaction and Western blot assay. The effect of CKD-WID on osteoclast formation was measured by tartrate-resistant acid phosphatase (TRAP) staining, F-actin ring formation staining, and assays for bone resorption activity. RANKL in the presence of MSU significantly induced HDAC6 gene and protein expression in RAW 264.7 cells. CKD-WID markedly suppressed the expression of osteoclast-related markers such as c-Fos, TRAP, cathepsin K, and carbonic anhydrase II induced by co-stimulation with RANKL and MSU in RAW 264.7 cells. Transcription factor NFATc1 mRNA expression and nuclear NFATc1 protein expression induced by co-stimulation with RANKL and MSU were significantly inhibited by CKD-WID treatment. CKD-WID also decreased the number of TRAP-positive multinuclear cells and F-actin ring-positive cells and attenuated bone resorption activity. Co-stimulation with RANKL and MSU increased calcineurin gene and protein expression, which was significantly blocked by CKD-WID treatment. The HDAC6 inhibitor CKD-WID suppressed MSU-induced osteoclast formation through blocking the calcineurin-NFAT pathway in RAW 264.7 cells. This suggests that HDAC6 is considered a therapeutic target in uric acid-mediated osteoclastogenesis. [ABSTRACT FROM AUTHOR]

Gout is characterized by the formation of monosodium urate crystals in peripheral joints. We carried out laboratory studies to investigate the effect of adding nine different methylxanthines and two different methylated uric acid derivatives on the development of these crystals over the course of 96 h in a medium whose composition was similar to that of synovial fluid. Our results showed that 7-methylxanthine reduced or totally prevented crystal formation; 1-methylxanthine, 3-methylxanthine, 7-methyluric acid, and 1,3-dimethyluric acid had weaker effects, and the other molecules had no apparent effect. The presented results indicate that a 7-methylxanthine concentration of about 6 × 10−5 M (10 mg/L) prevented the formation of crystals for an initial urate concentration of 1.78 × 10−3 M (300 mg/L) in the presence of 0.4 M of Na+ for 96 h at 25 °C and a pH of 7.4. We attribute these results to alterations in thermodynamics, not kinetics. Our results suggest that prevention of crystallization in vivo could be achieved by direct oral administration of 7-methylxanthine or other methylxanthines that are metabolized to 7-methylxanthine. For example, the hepatic metabolism of theobromine leads to significant plasma levels of 7-methylxanthine (14% of the initial theobromine concentration) and 3-methylxanthine (6% of the initial theobromine concentration); however, 7-methyluric acid is present at very low concentrations in the plasma. It is important to consider that several of the specific molecules we examined (theobromine, caffeine, theophylline, dyphylline, etophylline, and pentoxifylline) did not directly affect crystallization.

The increased utilization of titanium dioxide (TiO2) nanoparticles (TNPs) in various industrial and consumer products has raised concerns regarding its harmful effect due to its accumulation within the different systems of the human body. Here, we focused on the influence of TNPs on the growth and aggregation of two crucial crystalline substances, calcium phosphate (CaP) and monosodium urate (MSU), particularly its implications in gout disease. In this study, we adopted microscopic techniques and generated kinetic models to examine the interactions between TNPs, CaP and MSU, and crystallization, under controlled laboratory conditions. Our findings reveal that TNPs not only facilitate the growth of these crystals but also promote their co-aggregations. Crystal dissolution kinetics also exhibit that an increase in TNPs concentration corresponds to a reduction in the dissolution rate of CaP and MSU crystals in presence of the dissoluting agent hydroxycitrate (Hcit). These observations suggest that TNPs can stabilize CaP+MSU mixed crystals, which underscores the significance of TNPs’ exposure in the pathogenesis of gout disease.

Purpose of reviewThe present review addresses diagnostic methods for crystalline arthritis including synovial fluid analysis, ultrasound, and dual energy CT scan (DECT).Recent findingsThere are new technologies on the horizon to improve the ease, sensitivity, and specificity of synovial fluid analysis. Raman spectroscopy uses the spectral signature that results from a material's unique energy absorption and scatter for crystal identification. Lens-free microscopy directly images synovial fluid aspirate on to a complementary metal-oxide semiconductor chip, providing a high-resolution, wide field of view (∼20 mm) image. Raman spectroscopy and lens-free microscopy may provide additional benefit over compensated polarized light microscopy synovial fluid analysis by quantifying crystal density in synovial fluid samples. Ultrasound and DECT have good sensitivity and specificity for the identification of monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals. However, both have limitations in patients with recent onset gout and low urate burdens.SummaryNew technologies promise improved methods for detection of MSU and CPP crystals. At this time, limitations of these technologies do not replace the need for synovial fluid aspiration for confirmation of crystal detection. None of these technologies address the often concomitant indication to rule out infectious arthritis.

Introduction: Efficient and complete debridement of intra-articular deposits of monosodium urate crystals is rarely achieved by existing arthroscopic tools such as shavers or radiofrequency ablation, while cavitation technology represents a prospective solution for the non-invasive clearance of adhesions at intra-articular interfaces. Methods: Simulation modeling was conducted to identify the optimal parameters for the device, including nozzle diameters and jet pressures. Gouty arthritis model was established in twelve rats that were equally and randomly allocated into a cavitation debridement group or a curette debridement group. A direct injection nozzle was designed and then applied on animal model to verify the effect of the cavitation jet device on the removal of crystal deposits. Image analysis was performed to evaluate the clearance efficiency of the cavitation device and the pathological features of surrounding tissue were collected in all groups. Results: To maximize cavitation with the practical requirements of the operation, an experimental rig was applied, including a 1 mm direct injection nozzle with a jet pressure of 2.0 MPa at a distance of 20 mm and a nitrogen bottle as high-pressure gas source. With regards to feasibility of the device, the clearance rates in the cavitation group were over 97% and were significantly different from the control group. Pathological examination showed that the deposition of monosodium urate crystals was removed completely while preserving the normal structure of the collagen fibers. Conclusions: We developed a promising surgical device to efficiently remove intra-articular deposits of monosodium urate crystals. The feasibility and safety profile of the device were also verified in a rat model. Our findings provide a non-invasive method for the intraoperative treatment of refractory gouty arthritis. [ABSTRACT FROM AUTHOR]

Gout is a metabolic arthritis that originates from increased accumulation of monosodium urate (MSU) crystals in joints. This work aimed to evaluate the antioxidant and anti-inflammatory activities of the hydromethanolic extract of Gnidia kraussiana (HEGK) using model of Gouty arthritis on mice. The total polyphenol, flavonoid, tannin content and the antioxidant activity of HEGK were also evaluated. MSU-injected mice were treated daily for 3 days with HEGK (25, 50 and 100 mg/kg). Indomethacin and colchicin were used as reference drugs. Paw oedema and body temperature were measured at different time intervals post-injection. Malondialdehyde, acid phosphatase, β-Galactosidase, catalase, superoxide dismutase and glutathione levels were evaluated. HEGK is rich in polyphenol (129.93 mg/100 g), flavonoid (67.78 mg/100 g) and tannin conferring it a high antioxidant activity. Acute oral toxicity of HEGK resulted in LD50 greater than 2000 mg/kg. Oral administration of HEGK induced a significant decrease in the oedema of legs injected with urate crystals and reduced the release of acid phosphatase and β-Galactosidase. A model of oxidative damage was successfully established, revealing a significant increase in malondialdehyde and inhibition of antioxidants, including superoxide dismutase, catalase and glutathione activity. Thus, HEGK can actively inhibit the effect of inflammatory mediators in gouty arthritis. [ABSTRACT FROM AUTHOR]

Objective: To determine the effects of berberine (BBR) on the activation of toll-like receptor 4 (TLR4), nuclear factor (NF)κB (NF-κB) signaling and NLRP3 inflammasome in patients with gout. Methods: Peripheral blood mononuclear cells (PBMCs) were obtained from 24 acute (AP) and 41 non-acute (NAP) phases of primary gout patients, respectively, as well as 30 healthy controls (HC). TLR4, NF-κB (p65), NLRP3, apoptosis-associated specklike protein containing a CARD (PYCARD), cysteinyl aspartate specific proteinase-1 (CASP1), and interleukin-1β (IL-1β) mRNA expression levels in PBMCs were measured by quantitative reverse transcriptase polymerase chain reaction. The protein levels of TLR4, myeloid differentiation factor 88 (MyD88), NF-κB (p50/65), inhibitor of kappa B kinase α/β (IKKα/β), NF-κB inhibitor α (IKBα), phospho-IKKα/β (p-IKKα/β), NLRP3, PYCARD, and CASP1 were monitored by Western blotting. Serum IL-1β protein level was measured using enzyme-linked immunosorbent assay (ELISA). In addition, PBMCs from HC and macrophages derived from a spontaneously immortalized monocyte-like cell line (THP-1) were stimulated using monosodium urate (MSU, 100 µg/mL), 0.1% dimethyl sulfoxide, 25 µmol/L BBR, and 10, 25, and 50 µmol/L BBR+100 µg/mL MSU for different time periods. The protein levels of IL-1β and IL-18 in cell culture supernatants was measured by ELISA, and the protein expressions of TLR4, MyD88, NF-κB (p50/p65), IKKα/β, I κBβ, p-IKKα/β, NLRP3, PYCARD, and CASP1 in macrophages were analyzed by Western blotting. Results: (1) TLR4, NF-κB (p65), PYCARD, CASP1, and IL-1β mRNA levels in PBMCs were significantly higher in the AP group than in the HC group (P<0.05). The NLRP3 mRNA expression levels in PBMCs were found to be significantly lower in the AP and NAP groups than in the HC group (P<0.05, P<0.01). (2) The protein levels of TLR4, IKKβ, MyD88, NF-κB, p-IKKα/β, PYCARD, and CASP1 in PBMCs were significantly higher, and those of IκBα, IKKα, and NLRP3 were found to be significantly lower in the AP group than in the HC group (P<0.05 or P<0.01). (3) The serum IL-1β protein levels were significantly higher in the AP and NAP groups than in the HC group (P<0.01). (4) The IL-1β protein level was significantly lower in the culture supernatants of the PBMCs stimulated with MSU for 3 and 6 h in the 25 and 50 µmoL/L BBR groups compared with that in the MSU group (P<0.01). (5) The protein levels of IL-1β and IL-18 were also significantly lower in the culture supernatants of macrophages stimulated with MSU for 3 and 6 h in BBR groups compared with those in the MSU group (P<0.01). (6) The protein levels of TLR4, MyD88, NF-κB (p50, p65, p105), IKKα/β, p-IκBα, p-IKKα/β, PYCARD, and CASP1 were significantly differed between the macrophages stimulated with MSU for 0.5 and 6 h in BBR groups compared with those in the MSU group (P<0.05 or P<0.01). Conclusions: Activation of TLR4-NFκB signaling and NLRP3 inflammasome by MSU crystals drives the progression of gout inflammation. BBR ameliorates gouty inflammation, which is mechanistically associated with its regulation of TLR4-NF-κB signaling and NLRP3 inflammasome expression. [ABSTRACT FROM AUTHOR]

Background and Aim: Gouty arthritis is a metabolic disorder involving monosodium urate (MSU) crystal deposition as a key initiator of acute inflammation. Dysregulation of the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome is associated with the pathogenesis of gout through the maturation of interleukin-1β. Piperine (PIP) is a phytochemical with an anti-inflammatory activity that has the potential as an alternative treatment for gout. In this study, we examined the effect of PIP in immunosuppression of gout inflammation through the regulation of the NLRP3 inflammasome. Materials and Methods: An in silico study was done by pharmacodynamic modeling of PIP in suppressing MSU-induced inflammation through disruption of the NLRP3 inflammasome. In vivo tests, including inflammatory assessment, histopathology, cytology, estimation of lipid peroxidation index, and detection of systemic inflammatory reactants, were performed on two groups using preventive and curative protocols. Results: In silico studies of molecular docking demonstrated the activity of PIP as a competitive inhibitor of the mitogen-activated protein kinases/nuclear factor-kappaB axis, upstream of the NLRP3 inflammasome. Analysis of gout models with curative and preventive protocols revealed the immunosuppression activity of PIP by reducing inflammatory symptoms, inhibiting tophus formation resulting from NETosis, reducing cartilage erosion, inhibiting leukocyte exudation, suppressing lipid peroxidation index, and inhibiting the production of C-reactive protein. Conclusion: The results demonstrate the activity of PIP as an immunosuppressant in gout flare. These findings indicate the potential of PIP as a candidate for prophylactic and therapeutic agent for the treatment of gouty arthritis.

Periodontitis is one of the most prevalent diseases in oral cavity, which could not merely lead to the destruction of supporting or surrounding tooth structures but also affect the whole-body health such as the digestive and nervous systems. Epidemiological investigations suggested that in some developed countries, more than 45% or even 50% population were suffering from periodontitis. However, the prevalence increases with age remarkably and it is investigated that a high prevalence (>50%) is affecting the elderly who is over 65 years old. There is an increasing interest in the direct and indirect relationships between periodontitis and hyperuricemia. Currently, hyperuricemia has become the second major metabolic disease in modern society and the prevalence of hyperuricemia among adult males and females was 21.7% and 14.4% respectively. As an inflammatory disease associated with various systemic diseases, periodontitis may have certain connections with hyperuricemia. Partial existing research announced that hyperuricemia could act as an inhibitory factor for periodontitis, while other scholars presented that a high uric acid (UA) level was more likely to aggravate inflammatory immune response and lead to more serious tissue destruction. This article provides a detailed and comprehensive overview of the relationship underlying hyperuricemia and periodontitis in the molecular mechanisms. Given the impact of hyperuricemia, this review could provide insight into its comorbidities. [ABSTRACT FROM AUTHOR]

Gouty arthritis is an inflammatory disease induced by monosodium urate (MSU), and is closely related to the activation of inflammasomes. Calycosin plays an anti‐inflammatory role in arthritis. This study explored the mechanism of Calycosin in MSU‐induced gouty arthritis. MSU‐induced gouty arthritis mouse models with or without treatment of Calycosin were established, and physiological and pathological indicators were determined. Similarly, peripheral blood mononuclear cells (PBMCs) and THP‐1 macrophages were used in vitro. Lactate dehydrogenase (LDH) was tested. The degree of centrifugal infiltration was detected by immunofluorescence. ELISA and quantitative reverse‐transcription polymerase chain reaction were conducted to determine the levels of inflammatory factors. Immunohistochemistry, immunofluorescence, and flow cytometry were utilized to detect the content of caspase‐1. Protein expressions of NF‐κB‐, p62‐Keap1 pathway‐, and pyroptosis‐related factors were examined by western blot. In MSU‐induced mouse models, calycosin increased mechanical hyperalgesia but decreased the swelling index of the mouse knee joint in a time‐dependent manner. MSU treatment increased inflammatory cells and LysM‐eGFP+ neutrophils recruitment in vivo, and promoted the LDH content in vitro, and meanwhile, calycosin reversed the aforementioned effects of MSU. In addition, calycosin repressed the release of inflammatory factors, promoted p62 level and diminished the levels of AIM2, caspase‐1, ASC, IL‐1β, Keap1, Cleaved GSDMD, and Cleaved caspase‐1 and phosphorylation of p65 and IκBα in MSU‐induced mouse or cell models. Furthermore, AIM2 silencing also inhibited MSU‐induced inflammation and pyroptosis. Collectively, calycosin may inhibit AIM2 inflammasomes‐mediated inflammation and pyroptosis through NF‐κB and p62‐Keap1 pathways, ultimately playing a protective role in gouty arthritis. [ABSTRACT FROM AUTHOR]