Geraniin restricts inflammasome activation and macrophage pyroptosis by preventing the interaction between ASC and NLRP3 to exert anti-inflammatory effects

Geraniin, a chemical component of the traditional Chinese medicine geranii herba, possesses anti-inflammatory and anti-oxidative activities. However, its anti-inflammatory role in managing NLRP3 inflammasome and pyroptosis remains to be elucidated. To investigate the anti-inflammation mechanism of geraniin, LPS-primed macrophages were incubated with classical activators of NLRP3 inflammasome (such as ATP, Nigericin, or MSU crystals), and MSU crystals were injected into the ankle joints of mice to establish an acute gouty arthritis model. The propidium iodide (PI) staining results showed that geraniin could restrain cell death in the ATP- or nigericin-stimulated bone marrow-derived macrophages (BMDMs). Geraniin decreased the release of lactate dehydrogenase (LDH) and interleukin (IL)-1β from cytoplasm to cell supernatant. Geraniin also inhibited the expression of caspase-1 p20, IL-1β in cell supernatant and N-terminal of gasdermin D (GSDMD-NT) while blocking the oligomerization of ASC to form speck. The inhibitory effects of geraniin on caspase-1 p20, IL-1β, GSDMD-NT, and ASC speck were not observed in NLRP3 knockout (NLRP3-/-) BMDMs. Hence, the resistance of geraniin to inflammasome and pyroptosis was contingent upon NLRP3 presence. Geraniin reduced reactive oxygen species (ROS) production and maintained mitochondrial membrane potential while preventing interaction between ASC and NLRP3 protein. Additionally, geraniin diminished MSU crystal-induced mouse ankle joint swelling and IL-1β expression. Geraniin blocked the recruitment of neutrophils and macrophages to the synovium of joints. Our results demonstrate that geraniin prevents the assembly of ASC and NLRP3 through its antioxidant effect, thereby inhibiting inflammasome activation, pyroptosis, and IL-1β release to provide potential insights for gouty arthritis targeted therapy.

Tetrandrine alleviates inflammation and promotes macrophage M2 polarization in gouty arthritis by NF-κB-mediated Lcp1

Gouty arthritis (GA) is an inflammatory disease caused by the deposition of monosodium urate (MSU) crystals into joints. Tetrandrine (TET) is a bisbenzylisoquinoline alkaloid extracted from the root of Stephania tetrandra and can exert an anti-inflammatory function in different diseases. Nevertheless, the specific function of TET in GA remains unclear. We established the GA mouse model by MSU injection into joints of mice. Paw volume and gait score were detected for measuring the degree of joint swelling and the situation of joint dysfunction. Western blot were utilized to test the alterations of M1-related factors (IL-6, IL-1β, TNF-α, IL-12, and iNOS) and M2-related factors (Mgl1, Mgl2, Pgc1-β, Arg-1, and IL-10). The activity of NF-κB p65 in tissues was determined. The interaction of NF-κB p65 and Lcp1 was measured by ChIP and luciferase reporter assay. Lcp1 KO mice were utilized to detect the effect of Lcp1 depletion on GA process. TET treatment markedly suppressed MSU-induced joint swelling, joint dysfunction, and joint injury in GA mice. TET can also reduce inflammatory reactions in MUS-induced mice. Furthermore, we proved that TET facilitated M2 macrophage polarization and inhibited M1 macrophage polarization in GA mice. In addition, TET was found to inhibit NF-κB activity and NF-κB-mediated Lcp1 expression. Lcp1 knockdown can improve joint injury and promote M2 macrophage polarization in GA mice, while this effect was further enhanced by TET. TET alleviates inflammation and facilitates macrophage M2 polarization in GA by NF-κB-mediated Lcp1.

Effects of evodiamine on ROS/TXNIP/NLRP3 pathway against gouty arthritis

Evodiamine (EVO) was tested on acute gouty arthritis rats to investigate its anti-inflammatory effect. Seventy-two male Sprague-Dawley (SD) rats were randomly assigned into the control, model, high, medium, and low dose of EVO groups and colchicine group. The ankle swelling degrees were measured at 2 h, 6 h, and 24 h following sodium urate injection into ankle joint. Histopathological examination was performed 24 h after injection. Reactive oxygen species (ROS) content in the ankle joint was detected using chemical fluorescence. Serum interleukin-1β (IL-1β), interleukin-18 (IL-18), and tumor necrosis factor-α (TNF-α) content were determined by ELISA. Serum xanthine oxidase (XOD), superoxide dismutase (SOD), and malondialdehyde (MDA) were determined by spectrophotometry. The expressions of thioredoxin-interacting protein (TXNIP), NOD-like receptor thermal protein domain associated protein 3 (NLRP3), pro-caspase-1, caspase-1, and apoptosis-related spot like protein (ASC) in synovium were detected by Western blot. Evodiamine alleviated the ankle swelling of the affected foot in gouty arthritis rats and reduced inflammatory cell infiltration in joint synovial tissue. Evodiamine also decreased the content of serum inflammatory factors including IL-1β, IL-18, and TNF-α, and increased serum SOD activity, while it decreased serum XOD, MDA activity, and ROS level. Moreover, evodiamine downregulated the protein expression levels of TXNIP, NLRP3, pro-caspase-1, cleaved caspae-1, and ASC. The mechanism of EVO in treating gouty arthritis is associated with the inhibition of NLRP3 inflammasome by regulating the ROS/TXNIP/NLRP3 signaling pathway.

Mechanism of DaiTongXiao in the treatment of gouty arthritis through the NLRP3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

DaiTongXiao (DTX) is a traditional Chinese Dai folk formulation utilized for gouty arthritis treatment, with substantial evidence supporting its anti-inflammatory properties. The NLRP3 inflammasome disorder is tightly linked to the development of many inflammatory diseases.

AIM OF THE STUDY

To elucidate the therapeutic efficacy of DTX in gouty arthritis and reveal its potential underlying mechanism.

MATERIALS AND METHODS

The primary active constituents in DTX were determined through ultraviolet spectrophotometry and gas chromatography. Rats underwent induction with monosodium urate (MSU), followed by treatment of J774A.1 cells with adenosine triphosphate (ATP) activation and lipopolysaccharide (LPS) induction and the subsequent culture in Dulbecco's modified Eagle's medium. The degree of foot joint swelling in rats was assessed, and ankle joints were evaluated through H&E staining. Enzyme-linked immunosorbent assay was performed to measure the levels of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α in both serum and cells. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to determine the relative mRNA expression levels of NLRP3, ASC, Caspase-1, and NF-κB in J774A.1 macrophages. The expression of NLRP3, ASC, Caspase-1, and NF-κB was examined by western blotting.

RESULTS

DTX could alleviate MSU-induced joint swelling in rats, as evidenced by a reduction in joint inflammation. Moreover, DTX effectively enhanced the survival rate of J774A.1 cells following LPS induction and ATP activation. Furthermore, DTX significantly reduced IL-1β, IL-6, IL-8, and TNF-α levels in both cell culture medium and rat serum. RT-PCR results revealed that DTX notably downregulated the mRNA expression levels of NLRP3, ASC, Caspase-1, and NF-κB in J774A.1 cells. Additionally, DTX downregulated NLRP3, ASC, NF-κB, and Caspase-1 expression in the joint tissue.

CONCLUSIONS

DTX exerts a significant anti-gouty arthritis effect, with its mechanism being tightly linked to the NLRP3 inflammatory signaling pathway. This pathway may be modulated by inhibiting IL-1β differentiation and maturation by downregulating NLRP3, ASC, Caspase-1, and NF-κB protein expression. This, in turn, leads to a reduction in the release of IL-6, IL-8, and TNF-α, ultimately impeding gouty arthritis progression.

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.

[Mechanism of acteoside in prevention and treatment of gouty arthritis based on liver metabolomics]

This study aims to reveal the effect of acteoside on gouty arthritis(GA) in rats based on liver metabolomics. The ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS) was employed to search for the potential biomarkers and metabolic pathways. SD rats were randomly assigned into blank, model, colchicine(0.3 mg·kg~(-1)), and high-, medium-, low-dose(200, 100, and 50 mg·kg~(-1), respectively) acteoside groups(n=7). The rats were administrated once a day for 7 continuous days. Monosodium urate(MSU) was used to induce GA model in rats during administration. The degree of joint swelling and pathological changes of synovial tissue in rats were observed, and the levels of interleukin(IL)-1β, IL-18 and tumor necrosis factor(TNF)-α in the synovial tissue of rats were measured. UPLC-Q-TOF-MS was employed to collect rat liver data, and Progenesis QI and EZ info were used for data analysis. Human Metabolomics Database(HMDB) and Kyoto Encyclopedia of Genes and Genomes(KEGG) were employed to predict the potential biomarkers and metabolic pathways. The results showed that acteoside alleviated joint swelling, reduced synovial tissue damage, and lowered the levels of inflammatory cytokines in GA rats. A total of 19 common biomarkers were identified, 17 of which can be regulated by acteoside. Seven metabolic pathways were enriched, such as glycerophospholipid metabolism, linoleic acid metabolism, and taurine and hypotaurine metabolism, among which glycerophospholipid metabolism was strongly disturbed. The metabolomics analysis suggested that acteoside may down-regulate the expression of inflammatory cytokines and alleviate the symptoms of GA rats by regulating glycerophospholipid metabolism, linoleic acid metabolism, and taurine and hypotaurine metabolism. The findings provide a reference for future research and development of acteoside.

Novel Leflunomide Analog, UTLOH-4e, Ameliorates Gouty Arthritis Induced by Monosodium Urate Via NF-κB/NLRP3 Signaling Pathway

BACKGROUND

Gouty arthritis (GA) is a common form of inflammatory arthritis caused by intra-articular deposition of monosodium urate (MSU) crystals; however, there is a tremendous lack of safe and effective therapy in the clinic.

OBJECTIVE

The goal of this work was to investigate a novel leflunomide analogue, N-(2,4- dihydroxyphenyl)-5-methyl-1,2-oxazole-3-carboxamide (UTLOH-4e), for its potential to prevent/ treat gouty arthritis.

METHODS

In this study, the anti-inflammatory activity of UTLOH-4e was evaluated by MSUinduced GA model in vivo and in vitro, and the molecular docking test was applied to estimate the affinity of UTLOH-4e/UTL-5g/b for MAPKs, NF-κB, and NLRP3.

RESULTS

In vitro, UTLOH-4e (1~100 μM) treatment inhibited the inflammatory reaction with no obvious cytotoxicity in PMA-induced THP-1 macrophages exposed to MSU crystals for 24 h, involving the prominent decreased production and gene expression of IL-1β, TNF-α, and IL-6. Western blot analyses demonstrated that UTLOH-4e (1~100 μM) significantly suppressed the activation of NLRP3 inflammasomes, NF-κB, and MAPK pathways. Furthermore, the data from the experiment on gouty rats induced by intra-articular injection of MSU crystal confirmed that UTLOH-4e markedly ameliorated rat paw swelling, articular synovium inflammation and reduced the concentration of IL-1β and TNF-α in serum through down-regulating NLRP3 protein expression.

CONCLUSION

These results manifested that UTLOH-4e ameliorates GA induced by MSU crystals, which contributes to the modulation of NF-κB/ NLRP3 signaling pathway, suggesting that UTLOH- 4e is a promising and potent drug candidate for the prevention and treatment of gouty arthritis.

Non-loading versus loading low-dose colchicine in acute crystal-associated arthritis: A double-blinded randomized controlled study

INTRODUCTION

This study aimed to compare the efficacy of non-loading versus loading low-dose colchicine in patients with acute crystal-associated arthritis.

MATERIALS AND METHODS

All in-patients who were admitted to Chiang Mai University Hospital with non-arthritis disease and developed acute crystal-associated arthritis during admission (within 48 h after arthritis onset) were invited to join this study. The patients were randomized into two groups. Patients in Group I (non-loading group) and Group II (loading group) received colchicine at 1.2 and 2.4 mg in the first 24 h, respectively. The primary outcome was the patients' pain response at 24 h after treatment.

RESULTS

Of 80 patients, 49 were acute gouty arthritis, and 31 acute calcium pyrophosphate (CPP) arthritis. The mean [95% CI] pain score was no different between Groups I and II at the baseline level (6.46[5.72-7.19] vs. 6.654[5.85-7.44], p = .867) and at 24 h (3.13[2.43-3.82] vs. 3.18[2.42-3.93], p = .907). The proportion of patients with ≥50% pain reduction was not different (57.50% vs. 55.00%, p = .822). Sensitivity analysis among patients with a baseline pain score of ≥4 showed the same pattern of response. Mild diarrhea was common and comparable in both groups. Subgroup analysis according to renal function (eGFR < 60 vs. ≥60 mL/min/1.73 m2 ) or type of crystals (acute gouty arthritis vs. acute CPP arthritis) also showed the same pattern of response.

CONCLUSION

Non-loading low-dose colchicine was as effective as loading low-dose colchicine in patients with acute crystal-associated arthritis, regardless of renal function or type of crystals.

Highly expressed long non-coding RNA SNHG14 activated MSU-induced inflammatory response in acute gout arthritis through targeting miR-223-3p

AIM

According to reports, long non-coding RNAs (lncRNAs) are involved in the regulation of many inflammatory diseases. Here, our main purpose was to ascertain the expression data of lncRNA SNHG14 in acute gouty arthritis (AGA) and to explore its possible mechanism in the regulation of AGA.

METHOD

Reverse transcription quantitative polymerase chain reaction technology was supplied to detect the lncRNA SNHG14 expression. A receiver operating characteristics curve was drawn to estimate the accuracy of lncRNA SNHG14 in AGA diagnosis. An in vitro AGA cell model was constructed by inducing THP-1 cells with monosodium urate (MSU). The concentrations of inflammatory factors such as interleukin-1β, interleukin-6, and tumor necrosis factor-α were measured by enzyme-linked immunosorbent assay. The luciferase reporter gene was used to verify the relationship between lncRNA SNHG14 and miR-223-3p.

RESULTS

In clinical analysis, the levels of serum lncRNA SNHG14 in AGA patients were significantly higher than those in the control group. Abnormally elevated lncRNA SNHG14 has high sensitivity and specificity for AGA diagnosis. In in vitro cell experiments, silencing lncRNA SNHG14 inhibited the inflammatory response of THP-1 cells stimulated by MSU, and the luciferase reporter gene proved that lncRNA SNHG14 could bind to miR-223-3p. In addition, the level of miR-223-3p declined in AGA patients and the AGA cell model. Overexpression of miR-223-3p is helpful to alleviate an MSU-induced inflammatory response.

CONCLUSION

In the AGA cell model, lncRNA SNHG14, as an miR-223-3p sponge, induces a cellular inflammatory response by controlling the level of miR-223-3p, so aggravating the disease progress of AGA.

New animal model of chronic gout reproduces pathological features of the disease in humans

OBJECTIVES

Gout, as the most prevalent form of inflammatory arthritis, necessitates the use of animal models to investigate the molecular mechanisms involved in its development. Therefore, our objective was to develop a novel chronic mouse model of gout that more closely mimics the progression of gout in humans.

METHODS

A novel chronic mouse model of gout was established by a simple method, which does not require high technical proficiency, predominantly involves daily intraperitoneal injections of potassium oxonate for approximately 4 months, combined with a high fat-diet and injections of acetic acid into the hind paws to facilitate the formation of monosodium urate (MSU). Arthritis scores and paw oedema were assessed, behavioural tests were conducted, and histopathological and imaging evaluations of the arthritic paw joints were performed.

RESULTS

After 4 months of induction, mice in the model group exhibited noticeable increases in arthritis severity, joint and cartilage damage, as well as bone erosion. Gomori's methenamine silver stain revealed the presence of MSU crystal deposition or tophi in the paw joints or ankle joints of up to 37.9% of the model mice (11 out of 29 mice). Moreover, treatment with benzbromarone effectively prevented the further development of gout or tophi formation in model mice.

CONCLUSIONS

Our model more accurately replicates the pathological features of gouty arthritis compared with gout induced by MSU crystal injections. Therefore, it is particularly suitable for further investigations into the pathogenesis of gout and also serves as a valuable platform for screening potential antigout agents.

Articular mobilization promotes improvement in functional and inflammatory parameters in a gouty arthritis model

OBJECTIVE

Gouty arthritis is characterized by painful inflammation due to the deposition of monosodium urate crystals in joint tissues. Despite available treatments, many patients experience ineffective management and adverse effects. This study evaluated a manual therapy protocol involving passive joint mobilization at the peak of inflammation in a gouty arthritis model using functional and inflammatory parameters.

METHODS

Twenty male Wistar rats, 12 weeks old, were divided into two groups (n=10 each): Gouty Arthritis and Control Groups, which were further subdivided into treated and untreated groups (n=5 each). The Gouty Arthritis Group received intraarticular knee injection of 50µL of monosodium urate crystals, while the Control Group received 50µL of phosphate buffered saline. The treatment involved a 9-minutes session of grade III joint mobilization (according to Maitland). Nociception, grip strength, and edema were evaluated before induction (EV0), 7 hours after assessment (EV1), immediately after treatment (EV2), and 1 hour after treatment (EV3). The animals were euthanized, and synovial fluid was collected to analyze leukocyte migration.

RESULTS

The model mimicked the signs of the Gouty Arthritis Group, with a decrease in the threshold of nociception and strength and an increase in edema and leukocyte count. The mobilization protocol significantly increased the nociceptive threshold and grip strength and reduced edema; however, it did not reverse the increase in leukocyte count.

CONCLUSION

Our results suggest that mobilization promotes analgesia and may modulate the inflammatory process owing to reduced edema and subtle attenuation of cell migration, which contributes to strength gain.

Kaempferol Attenuates Gouty Arthritis by Regulating the Balance of Th17/Treg Cells and Secretion of IL-17

Kaempferol is a common flavonoid aglycone widely found in plants. It exhibits beneficial therapeutic effects in the treatment of arthritis. However, the effects of kaempferol on gouty arthritis (GA) have not been verified. This study aimed to explore the potential mechanisms by which kaempferol regulates GA by network pharmacology and experimental validation. Potential drug targets for GA were identified with a protein-protein interaction network. Then, we performed a KEGG pathway analysis to elucidate the major pathway involved in the kaempferol-mediated treatment of GA. In addition, the molecular docking was performed. A rat model of GA was constructed to verify the results of network pharmacology analysis and investigate the mechanism of kaempferol against GA. The network pharmacology study indicated that there were 275 common targets of kaempferol and GA treatment. Kaempferol exerted therapeutic effects on GA, in part, by regulating the IL-17, AGE-RAGE, p53, TNF, and FoxO signaling pathways. Molecular docking results showed that kaempferol stably docked with the core MMP9, ALB, CASP3, TNF, VEGFA, CCL2, CXCL8, AKT1, JUN, and INS. Experimental validation suggested that kaempferol eased MSU-induced mechanical allodynia, ankle edema, and inflammation. It significantly suppressed the expression of IL-1β, IL-6, TNF-α, and TGF-β1 and restored Th17/Treg imbalance in MSU-induced rats and IL-6-induced PBMCs. Kaempferol also affected RORγt and Foxp3 through IL-17 pathway. The present study clarifies the mechanism of kaempferol against GA and provides evidence to support its clinical use.

Autophagy induced by PP121 alleviates MSU crystal-induced acute gouty arthritis via inhibition of the NLRP3 inflammasome

Acute gouty arthritis (AGA) is a frequent self-limiting inflammatory condition produced by the deposition of monosodium urate (MSU) crystals in the joints and periarticular tissues of patients with hyperuricemia. However, no effective interventional measures currently exist for AGA. Pyroptosis, a kind of pro-inflammatory programmed cell death, plays a crucial role in MSU crystal-induced inflammation and represents a potential treatment target for AGA. Therefore, we determined the therapeutic benefits and mechanism of PP121, a pyroptosis-related compound, on AGA. First, we injected an MSU crystal solution intra-articularly into the left foot pad of C57BL/6 mice to create an AGA mouse model. Subsequent treatment with PP121 substantially decreased tissue damage, pro-inflammatory cytokine release, and inflammatory cell infiltration caused by MSU crystals in the ankle joint. Consistent with these observations, the beneficial effects of PP121 on AGA were cancelled in Beclin1+/-(Becn1+/-) mice. Furthermore, after PP121 treatment, super-resolution microscopy revealed a strong relationship between lysosome-connected membrane protein/light chain 3 positive vesicles and the nucleotide-binding domain of leucine-rich family pyrin domain-containing 3 (NLPR3), demonstrating that PP121 promotes phagocytosis of the NLPR3 inflammasome. In summary, PP121-mediated autophagy can improve degradation of the NLRR3 inflammasome in AGA, which suggests the therapeutic potential of PP121 in AGA.

Neutrophil autophagy induced by monosodium urate crystals facilitates neutrophil extracellular traps formation and inflammation remission in gouty arthritis

Neutrophil extracellular traps (NETs) are composed of chromatin filaments coated with granular and cytosolic proteins, which contribute to the pathogenesis and progression of immune-related diseases. NETs are frequently observed in gouty arthritis, but the related mechanisms remain poorly understood. The aim of our study was to systematically elucidate the molecular mechanisms of self-remitting effects in gouty arthritis, and the causative relationship between neutrophil autophagy and NETs. The air pouch and paw edema model were used to simulate gouty arthritis in mice. Neutrophil infiltration and the formation of NETs were found in gouty arthritis. Interestingly, monosodium urate (MSU) crystals could induce the formation of NETs, degrade inflammatory factors, and alleviate the inflammatory response in gouty arthritis. In addition, MSU crystals resulted in profound molecular alterations in neutrophils using RNA-seq analysis, including autophagy activation. MSU crystals could activate neutrophil autophagy in vitro, and autophagy activators and inhibitors could regulate the formation of NETs. Furthermore, we explored the mechanism of autophagy-induced NETs. Autophagy related protein 7 (ATG7) produced by neutrophils stimulated with MSU crystals worked synergistically with p53 to enter the nucleus, promoting peptidyl arginine deiminase 4 (PAD4) expression, and inducing the formation of NETs. Finally, we substantiated that neutrophil autophagy regulates the severity of gouty arthritis via the formation of NETs in PAD4 -/- mice. Our results indicated that the autophagy of neutrophils regulates the formation of NETs and degrades inflammatory factors. Regulating autophagy and interfering with the formation of NETs represents a potential therapeutic approach against gouty arthritis during clinical practice.

Discovery and Characterization of Moracin C as an Anti-Gouty Arthritis/Hyperuricemia Candidate by Docking-Based Virtual Screening and Pharmacological Evaluation

In the present study, a natural product database of compounds associated with herbs traditionally verified to treat gout/hyperuricemia/arthritis was constructed. 3D-shape and docking-based virtual screening was conducted. To identify potential xanthine oxidase (XOD) inhibitors in the database, eight compounds with commercial availability were identified as high 3D-shape similarity with febuxostat (1), a known XOD inhibitor. Docking was used to further predict the possible interactions between XOD and these compounds. Moracin C (2), moracin D (3), and isoformononetin (8) exhibited higher docking scores and binding energies than other compounds. In vitro, 2 inhibited XOD with an IC50 value of 0.25 ± 0.14 μM, which is similar to that of 1 (0.16 ± 0.08 μM). In a hyperuricemic mouse model, 5-20 mg/kg 2 exhibited satisfying urate-lowering and XOD inhibitory effects. Compound 2 also exhibited antiarthritis activities. In RAW264.7 cells, 2 at 1-10 μM inhibited the expression of IL-1β and TNF-α induced by MSU. In an acute gouty arthritis model in SD rats, 5-20 mg/kg 2 significantly alleviated the toe swelling, inflammatory response, and dysfunction disorder caused by monosodium urate (MSU). Compound 2 inhibited serum IL-1β and TNF-α cytokines as well as reduced the expression of the NLRP3/ASC/caspase-1 inflammasome in joints. In summary, 2 was an effective compound for the treatment of hyperuricemia/gouty arthritis.

Acute severe gouty arthritis secondary to isotretinoin toxicity in a young male: a case report

Acute gouty arthritis is a recognized complication of hyperuricemia and one of the most common forms of inflammatory arthritis in adults. Drug-induced hyperuricemia is increasingly prevalent in clinical practice. Diuretics, antitubercular medications, and immunosuppressants are the common drugs associated with hyperuricemia. Oral isotretinoin is the drug of choice for different forms of severe acne and is rarely associated with hyperuricemia. We present the case of a 30-year-old male with severe acne vulgaris who was prescribed isotretinoin and later presented with acute gout. The patient developed hyperuricemia and swelling of the right first metatarsophalangeal joint within two months of isotretinoin commencement. There was a second episode of similar joint swelling three months later, parallel to the isotretinoin rechallenge. The dose of isotretinoin was reduced with the addition of febuxostat. The patient did not develop further episodes and remained symptom-free without urate-lowering therapy.

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

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

Resveratrol alleviates MSU-induced gouty arthritis in rats through inhibition of HIF-1α- and NLRP3-derived IL-1β secretion in macrophages

Gouty arthritis is an acute and chronic joint inflammatory joint disease characterized by the deposition of monosodium urate (MSU) crystals in joints and periarticular tissues. Resveratrol (3, 5, 4-trihydroxy-trans-stilbene, RV), a natural polyphenolic compound, has anti-inflammatory and antioxidant properties. The purpose of this study was to investigate the effect of resveratrol on rats with gouty arthritis and its molecular mechanism. THP-1-derived macrophages were induced by lipopolysaccharide (LPS) and MSU to create an in vitro gout cell inflammation model, and rats were injected with MSU crystals into the right ankle joint for an in vivo acute gouty arthritis model. We investigated the anti-inflammatory properties of resveratrol using these in vitro and in vitro models. Our findings suggested that resveratrol effectively reduced ankle swelling and synovial inflammation in a dose-dependent manner in rats with acute gouty arthritis, with almost the same effect as colchicine treatment. In MSU-treated THP-1-derived macrophages, resveratrol inhibited NLRP3 inflammasome activation and IL-1β secretion. Furthermore, resveratrol and the HIF-1α inhibitor PX478 both inhibited the expression of the NLRP3 inflammasome, IL-1β, and HIF-1α. This study demonstrated that resveratrol significantly improved the symptoms of acute gouty arthritis and its potential mechanism may be IL-1β reduction via HIF-1α modulation and inhibition of NLRP3 inflammasome activation. Our study might offer a novel sight for the treatment of gouty arthritis.

Component identification of modified sanmiao pills by UPLC-Xevo G2-XS QTOF and its anti-gouty arthritis mechanism based on network pharmacology and experimental verification

ETHNOPHARMACOLOGICAL RELEVANCE

Modified sanmiao pills (MSMP), a traditional Chinese medicine (TCM) formula, is consisted of rhizome of Smilax glabra Roxb., Cortexes of Phellodendron chinensis Schneid., rhizome of Atractylodes chinensis (DC.) Koidz., and roots of Cyathula officinalis Kuan. in a ratio of 3:3:2:1. This formula has been broadly applied to treat gouty arthritis (GA) in China.

AIMS OF THE STUDY

To elaborate the pharmacodynamic material basis and pharmacological mechanism of MSMP against GA.

MATERIALS AND METHODS

UPLC-Xevo G2-XS QTOF combined with UNIFI platform was applied to qualitatively assess the chemical compounds of MSMP. Network pharmacology and molecular docking were used to identify the active compounds, core targets and key pathways of MSMP against GA. The GA mice model was established by MSU suspension injecting into ankle joint. The swelling index of ankle joint, expressions of inflammatory cytokines, and histopathological changes in mice ankle joints were determined to validate the therapeutic effect of MSMP against GA. The protein expressions of TLRs/MyD88/NF-κB signaling pathway and NLRP3 inflammasome in vivo was detected by Western blotting.

RESULTS

In total, 34 chemical compounds and 302 potential targets of MSMP were ascertained, of which 28 were overlapping targets pertaining to GA. 143 KEGG enrichment pathway were obtained, of which the NOD-like receptor signaling pathway, Toll-like receptor signaling pathway, and NF-κB signaling pathway were strongly associated with GA. In silico study indicated that the active compounds had excellent binding affinity to core targets. In vivo study confirmed that MSMP observably decreased swelling index and alleviated pathological damage to ankle joints in acute GA mice. Besides, MSMP significantly inhibited the secretion of inflammatory cytokines (IL-1β, IL-6, and TNF-α) induced by MSU, as well as the expression levels of key proteins involved in TLRs/MyD88/NF-κB signaling pathway and NLRP3 inflammasome.

CONCLUSION

MSMP possessed a pronounced therapeutic effect on acute GA. Results from network pharmacology and molecular docking showed that obaculactone, oxyberberine, and neoisoastilbin might treat gouty arthritis by down-regulating TLRs/MyD88/NF-κB signaling pathway and NLRP3 inflammasome.

Pro-Inflammatory of PRDM1/SIRT2/NLRP3 Axis in Monosodium Urate-Induced Acute Gouty Arthritis

PR domain-containing 1 with zinc finger domain (PRDM1) has been reported as a promoter of inflammation, which is a critical process involved in the pathogenesis of acute gouty arthritis. Herein, we sought to ascertain the function of PRDM1 in the development of acute gouty arthritis and related mechanisms. At first, peripheral blood-derived monocytes from patients with acute gouty arthritis and healthy individuals were collected as experimental samples. Then, macrophages were induced from monocytes using phorbol myristate acetate (PMA). The expression patterns of PRDM1, sirtuin 2 (SIRT2), and NLR family, pyrin domain-containing 3 (NLRP3) were characterized by RT-qPCR and Western blot assay. PMA-induced macrophages were stimulated by monosodium urate (MSU) for in vitro experimentation. Meanwhile, a murine model of MSU-induced acute gouty arthritis was established for in vivo validation. PRDM1 was highly expressed while SIRT2 poorly expressed in patients with acute gouty arthritis. Loss of PRDM1 could reduce NLRP3 inflammasome and mature IL-1β levels and downregulate inflammatory cytokines in macrophages, which contributed to protection against acute gouty arthritis. Furthermore, results showed that PRDM1 could inhibit SIRT2 expression via binding to the deacetylase SIRT2 promoter. Finally, the in vivo experiments demonstrated that PRDM1 increased NLRP3 inflammasome and mature IL-1β through transcriptional inhibition of SIRT2, whereby aggravating MSU-induced acute gouty arthritis. To sum up, PRDM1 increased NLRP3 inflammasome through inhibiting SIRT2, consequently aggravating MSU-induced acute gouty arthritis.

Qingre Huazhuo Jiangsuan Decoction promotes autophagy by inhibiting PI3K/AKT/mTOR signaling pathway to relieve acute gouty arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Gout belongs to the category of "arthralgia syndrome" in traditional Chinese medicine. It is believed that gout is caused by stagnation of blood stasis, heat, and turbid toxin. Qingre Huazhuo Jiangsuan Decoction (QHJD) is a traditional Chinese medicine prescription developed from the classic Chinese medicine prescription Simiao powder to clear heat, remove turbidity, reduce acid, and reduce inflammation. Now Traditional Chinese Medicine (TCM) physicians often apply it to treat acute gouty arthritis (AGA). However, the mechanism of QHJD in relieving acute gouty arthritis is still unclear, and further research is needed.

AIM OF THE STUDY

Here, we aim to explore the potential mechanism of QHJD in relieving acute gouty arthritis.

MATERIALS AND METHODS

Acute gouty arthritis model was established by injecting monosodium urate (MSU) suspension into knee joint. The pathological state of synovial tissue in each group was evaluated by hematoxylin-eosin (HE) staining. The level of TNF-α, IL-6, and IL-1β were detected by enzyme-linked immunosorbent assay (ELISA). qRT-PCR was used to detect the mRNA expression of NLRP3, ATG5, ATG7, PI3K, AKT, and mTOR. The protein expression of LC3II/I, p62, ULK1, P-ULK1, Beclin-1, PI3K, AKT, mTOR, P-PI3K, P-AKT, and P-mTOR were detected by Western blot.

RESULTS

(1) The level of autophagy protein (mRNA) was significantly up-regulated in QHJD group and rapamycin, while the expression of autophagy protein (mRNA) was significantly downregulated in the 3-methyladenoenoic acid (3 MA) group; (2) QHJD and rapamycin significantly inhibited PI3K/AKT/mTOR pathway, while 3 MA group activated this pathway. (3) It was worth noting that after treatment with QHJD and rapamycin, the inflammatory pathological state of AGA synovial tissue was significantly reduced with the activation of the autophagy gene in knee synovial tissue, and the inhibition of PI3K/AKT/mTOR pathway.

CONCLUSIONS

This research revealed that QHJD activates autophagy by inhibiting PI3K/AKT/mTOR pathway, thereby relieving acute gouty arthritis.

Biomineralized Nanoscavenger Abrogates Proinflammatory Macrophage Polarization and Induces Neutrophil Clearance through Reverse Migration during Gouty Arthritis

The deposition of monosodium urate (MSU) crystals induces the overexpression of reactive oxygen species (ROS) and proinflammatory cytokines in residential macrophages, further promoting the infiltration of inflammatory leukocytes in the joints of gouty arthritis. Herein, a peroxidase-mimicking nanoscavenger was developed by forming manganese dioxide over albumin nanoparticles loaded with an anti-inflammatory drug, indomethacin (BIM), to block the secretion of ROS and COX2-induced proinflammatory cytokines in the MSU-induced gouty arthritis model. In the MSU-induced arthritis mouse model, the BIM nanoparticles alleviated joint swelling, which is attributed to the abrogation of ROS and inflammatory cytokine secretions from proinflammatory macrophages that induces neutrophil infiltration and fluid building up in the inflammation site. Further, the BIM nanoparticle treatment reduced the influx of macrophages and neutrophils in the injured region by blocking migration and inducing reverse migration in the zebrafish larva tail amputation model as well as in MSU-induced peritonitis and air pouch mouse models. Overall, the current strategy of employing biomineralized nanoscavengers for arthritis demonstrates clinical significance in dual blocking of peroxides and COX2 to prevent influx of inflammatory cells into the sites of inflammation.

MicroRNA-181a regulates Treg functions via TGF-β1/Smad axis in the spleen of mice with acute gouty arthritis induced by MSU crystals

Regulatory T cells (Tregs) play critical roles in restricting inflammatory pathogenesis and limiting undesirable Th2 response to environmental allergens. However, the role of miR-181a in regulating acute gouty arthritis (AGA) and Treg function remains unclear. This study aimed to investigate the potential roles of miR-181a in Treg immunity and the associated signaling pathway in the AGA mouse model. A solution with monosodium urate (MSU) crystals was injected into the joint tissue of mice to induce AGA. ELISA was used to examine inflammatory factors in blood samples, and flow cytometry was used to analyze Treg profile in mice with MSU-induced AGA. Cell proliferation and viability were assessed by CCK-8 assay. TGF-β1/Smad signaling activation was detected by western blot. We found that miR-181a expression showed a positive correlation with the changes of splenic Tregs percentage in AGA mice. miR-181a regulated the TGF-β1/Smad axis, since the transfection of miR-181a mimic increased the level of TGF-β1 and the phosphorylation of Smad2/3 in Tregs in AGA mice. Additionally, miR-181a mimic also promoted responses of Tregs via TGF-β1 in vitro and in vivo. Our work uncovered a vital role of miR-181a in the immune function of Treg cells by mediating the activity of the TGF-β1/Smad pathway in the AGA mouse model induced by MSU.

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.

Monosodium urate crystals with controlled shape and aspect ratio for elucidating the pathological progress of acute gout

Gout is a self-limiting inflammatory arthritis mediated by the precipitation of monosodium urate (MSU) crystals that further activate the NLRP3 inflammasome and initiate a cascade of inflammatory events. However, the key physicochemical properties of MSU crystals that determine the acute phase of gout have not been fully identified. In this study, a library of engineered MSU crystals with well-controlled size and shape is designed to explore their proinflammatory potentials in mediating the pathological progress of gout. It is demonstrated that medium-sized long aspect ratio MSU crystals induce more prominent IL-1β production in vitro due to enhanced cellular uptake and the production of mitochondrial reactive oxygen species (mtROS). The characteristics of MSU crystals are also correlated with their inflammatory potentials in both acute peritonitis and arthritis models. Furthermore, 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) is demonstrated to inhibit MSU-induced oxidative burst by removing plasma membrane cholesterol. As a result, it attenuates the inflammatory responses both in vitro and in vivo. Additionally, antioxidant N-acetylcysteine (NAC) is shown to alleviate acute gouty symptom by suppressing oxidative stress. This study identifies the key physicochemical properties of MSU crystals that mediate the pathogenesis of gout, which sheds light on novel design strategies for the intervention of gout.

The Protective Effects of Neoastilbin on Monosodium Urate Stimulated THP-1-Derived Macrophages and Gouty Arthritis in Mice through NF-κB and NLRP3 Inflammasome Pathways

Gouty arthritis (GA) is a frequent inflammatory disease characterized by pain, swelling, and stiffness of joints. Neoastilbin is a flavonoid isolated from the rhizome of Smilax glabra, which possesses various anti-inflammatory effects. However, the mechanism of neoastilbin in treating GA has not yet been clarified. Thus, this study was to investigate the protective effects of neoastilbin in both monosodium urate (MSU) stimulated THP-1-derived macrophages and the animal model of GA by injecting MSU into the ankle joints of mice. The levels of key inflammatory cytokines in MSU stimulated THP-1-derived macrophages were detected by enzyme-linked immunosorbent assay (ELISA) kits. Protein expressions of nuclear factor kappa B (NF-κB) and NOD-like receptor protein 3 (NLRP3) inflammasome pathways were further detected by Western blotting. In addition, swelling degree of ankle joints, the levels of inflammatory factors, infiltration of inflammatory cells and the expressions of related proteins were determined. Swelling degree and histopathological injury in ankle joints of MSU-injected mice were significantly decreased after being treated with neoastilbin. Moreover, neoastilbin significantly diminished the secretion of interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), suppressing the activation of NF-κB and NLRP3 inflammasome pathways in both MSU stimulated THP-1-derived macrophages and the mouse model of GA. In summary, neoastilbin could alleviate GA by inhibiting the NF-κB and NLRP3 inflammasome pathways, which provided some evidence for neoastilbin as a promising therapeutic agent for GA treatment.

Anti-Hyperuricemic Effect of Iron Oxide Nanoparticles against Monosodium Urate Crystals Induced Gouty Arthritis in BALB/c Mice

Iron oxide nanoparticles (FeO-NPs) exhibit exceptional properties which can be utilized in various aspects of biological sciences. In this experiment we investigated the anti-gout effectiveness of FeO-NPs in mice. BALB/c mice were induced gouty arthritis by administering monosodium urate (MSU) crystals. These gout induced mice were treated with three different concentrations of FeO-NPs (5 ppm, 10 ppm and 20 ppm). Precipitation method was utilized for the synthesis of FeO-NPs, these synthesized NPs were of average 54 nm in size and were characterized using XRD, SEM and EDS. FeO-NPs is given orally three weeks by using FeO-NPs solution to substitute drinking water. Blood biochemical parameters including liver function tests (LFTs), renal function tests (RFTs), lipid profile and blood count have been tested. It has been found that uric acid, blood urea and creatinine have decreased significantly after three weeks of FeO-NP administration (P Value < 0.001) thus suppressing hyperuricemia and gouty arthritis. Additionally, the liver enzymes analysis showed a slight increase in AST, ALT and alkaline phosphatase levels (P Value < 0.001). Histopathological research revealed no significant abnormal changes in the liver, muscle and kidney muscles of the test groups. The findings showed that FeO-NPs can be used for the successful treatment of hyperuricemic condition and gouty arthritis in the coming future in place of commercially available medicines.

Degenerative joint disease induced by repeated intra-articular injections of monosodium urate crystals in rats as investigated by translational imaging

The objective of this work was to assess the consequences of repeated intra-articular injection of monosodium urate (MSU) crystals with inflammasome priming by lipopolysaccharide (LPS) in order to simulate recurrent bouts of gout in rats. Translational imaging was applied to simultaneously detect and quantify injury in different areas of the knee joint. MSU/LPS induced joint swelling, synovial membrane thickening, fibrosis of the infrapatellar fat pad, tidemark breaching, and cartilage invasion by inflammatory cells. A higher sensitivity to mechanical stimulus was detected in paws of limbs receiving MSU/LPS compared to saline-injected limbs. In MSU/LPS-challenged joints, magnetic resonance imaging (MRI) revealed increased synovial fluid volume in the posterior region of the joint, alterations in the infrapatellar fat pad reflecting a progressive decrease of fat volume and fibrosis formation, and a significant increase in the relaxation time T2 in femoral cartilage, consistent with a reduction of proteoglycan content. MRI also showed cyst formation in the tibia, femur remodeling, and T2 reductions in extensor muscles consistent with fibrosis development. Repeated intra-articular MSU/LPS injections in the rat knee joint induced pathology in multiple tissues and may be a useful means to investigate the relationship between urate crystal deposition and the development of degenerative joint disease.

Pyroptosis inhibition alleviates potassium oxonate- and monosodium urate-induced gouty arthritis in mice

OBJECTIVES

Pyroptosis has been found implicated in several diseases, however, whether it was involved in gouty arthritis remained unclear. Our study was performed to uncover the role of pyroptosis in gouty arthritis based on a mice model.

METHODS

Mouse gouty arthritis model was established by injections of potassium oxonate (PO), monosodium urate (MSU) and pyroptosis suppressor disulfiram. The diameter of the ankle joints was measured, and ankle joints morphology was observed with hematoxylin-eosin (H&E) staining. Uric acid, creatinine and blood urea nitrogen (BUN) concentrations were measured, while cytokines level and xanthine oxidase (XOD) activity were quantified. Relative pyroptosis markers expressions were determined using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot as needed.

RESULTS

In mouse model, PO and MSU injections cause damage to right ankle, increase the root thickness ratio and uric acid, creatinine and BUN levels in serum and decrease the uric acid and creatinine levels in urine. Also, under PO and MSU treatment, up-regulated XOD activity, inflammatory cytokines levels and pyroptosis markers expressions are observed. Negative regulation of mice injury by disulfiram treatment is also observed.

CONCLUSION

Pyroptosis inhibition might alleviate PO- and MSU-induced gouty arthritis, providing possible therapeutic strategies for gouty arthritis.

The protective effects of S14G-humanin (HNG) against mono-sodium urate (MSU) crystals- induced gouty arthritis

Gout is a common and complex form of arthritis that has brought great inconveniences to the normal lives of patients. It is reported that oxidative stress and nod-like receptor family protein 3 (NLRP3) inflammasome-mediated inflammatory reactions are involved in the pathogenesis of gout arthritis. S14G-humanin (S14G-HNG) is a modified peptide of HNG with higher inhibitory activity on the accumulation and deposition of Aβ. Recently, S14G-HNG has been reported to exert great anti-inflammatory effects. The present study proposed to explore the possible therapeutic property of S14G-HNG against gout arthritis. An animal model was established by stimulation with mono-sodium urate (MSU) crystals, followed by treatment with colchicine and S14G-HNG, respectively. The elevated Gait score promoted synovitis score and activated myeloperoxidase (MPO) observed in MSU crystals-treated mice were significantly reversed by colchicine and S14G-HNG. Bone marrow-derived macrophages (BMDMs) were isolated from mice and stimulated with MSU crystals, followed by being treated with 25 and 50 μM S14G-HNG. The increased mitochondrial reactive oxygen species (ROS) and Malondialdehyde (MDA) levels, upregulated NADPH oxidase-4 (NOX-4), activated NLRP3 inflammasome, and elevated production of inflammatory factors in MSU crystals-treated BMDMs were dramatically reversed by S14G-HNG, accompanied by the upregulation of sirtuin type-1 (SIRT1). Lastly, the protective effects of S14G-HNG against MSU crystals-induced NLRP3 inflammasome activation were significantly abolished by the knockdown of SIRT1. In conclusion, our data reveal that S14G-HNG could possess potential benefits against MSU crystals-induced gout arthritis, with colchicine displaying a better effect.

Ameliorative Effects of Cardamonin on Monosodium Urate-Induced Gouty Arthritis through Inhibiting NLRP3 Inflammasome Mediation

Background and Objectives: Gouty arthritis is an acute inflammatory response caused by the precipitation of monosodium urate (MSU) crystals in joints. The triggering of MSU leads to increased production of inflammatory cytokines, such as interleukin-1β, which in turn lead to the formation of macromolecular complexes, referred to as inflammasomes. Thorough characterization of the NLRP3 inflammasome can be used as an indicator of an immune response against harmful stimuli. Cardamonin is a chalcone, mainly found in the seeds of Alpinia katsumadai, and exhibits anti-inflammatory activity by inhibiting the release of pro-inflammatory cytokines in vitro. However, the mechanism by which cardamonin treatment alleviates gouty arthritis has yet to be fully elucidated. Materials and Methods: In vitro or in vivo models were used to study whether cardamonimn inhibited NLRP3 inflammasome activation or suppressed gouty inflammation. Results: In the current study, we determined that most NLRP3 was released passively after MSU stimulation, and this release of NLRP3 promoted caspase-1 activation and IL-1β secretion. Cardamonin was shown to decrease both the activity of caspase-1 and secretion of IL-1β in J774A.1 macrophage cells subjected to MSU stimulation. Cardamonin was also shown to attenuate the production of COX-2 in MSU-stimulated J774A.1 macrophage cells. Finally, cardamonin reduced the thickness of the synovial lining and the infiltration of gouty arthritis in a rat model. Conclusions: Overall, cardamonin significantly attenuated IL-1β secretion, caspase-1 activity, and COX-2 production stimulated by MSU. These findings provide new insights into the molecular mechanisms underlying the effects of cardamonin treatment for gouty arthritis.

[Effect of rebamipide on the acute gouty arthritis in rats induced by monosodium urate crystals]

OBJECTIVE

To investigate the role of rebamipide in the treatment of acute gout arthritis rats induced by monosodium urate (MSU) crystal.

METHODS

Forty-two male rats were randomly divided into three groups (n=14). Group A was treated with oral rebamipide, group B with oral colchicine, and group C with oral placebo. The rats were monitored for the induction of arthritis with clinical manifestations and pathological changes, and the levels of interleukin (IL)-1β、IL-6、IL-10, and tumor necrosis factor (TNF)-α in serum were measured.

RESULTS

In group C, the clinical score and swelling index reached the maximum in 24 h, and then gradually decreased to 72 h. After 24 h of model induced, the clinical scores in group C were significantly higher than those in group A and group B [2 (1-3) vs. 0 (0-1) vs. 1 (0-2), P < 0.01], the swelling indexes in group C were significantly higher than those in group A and group B [0.36 (0.16-0.52) vs. 0.11 (0-0.20) vs. 0.12 (0-0.16), P < 0.01]. Histologically, after 24 h of model induced, there was a large number of neutrophil infiltration in the synovium of group C [scale score: 4 (2-4)], and there was no significant inflammatory cell infiltration in group A [1 (0-2)] and group B [1 (0-2)], the difference was statistically significant (P < 0.001). After 24 h of model induced, the levels of IL-1β, IL-6, IL-10, and TNF-α in serum of group C were significantly higher than those in group A and B [IL-1β: (41.86±5.72) vs. (27.35±7.47) vs. (27.76±5.28) ng/L, IL-6: (1 575.55±167.11) vs. (963.53±90.22) vs. (964.08±99.31) ng/L, IL-10: (37.96±3.76) vs. (21.68±4.83) vs. (16.20±2.49) ng/L, TNF-α: (21.32±1.34) vs. (15.82±2.54) vs. (17.35±7.47) μg/L, P < 0.001].

CONCLUSION

Rebamipide has a protective effect on acute gout arthritis rats induced by MUS crystals.

Melatonin Alleviates Acute Gouty Inflammation In Vivo and In Vitro

The aim of this study was to identify the effects of melatonin on acute gouty inflammation and to investigate the underlying mechanisms. We found significantly lower serum melatonin levels in gout patients in the acute phase than in those in the remission phase or in normal individuals. The mRNA expression of melatonin receptor 2 (MT2) was also lower in gout patients than in normal individuals. To verify the in-vivo role of melatonin, a gouty arthritis model was established by intraarticular injection of monosodium urate (MSU, 1 mg) crystals into the paws of C57BL/6 mice. Joint inflammation in the mouse model was evaluated by measuring the thickness of the right paw/left paw, and the inflammation index was determined by examining infiltrating neutrophils with haematoxylin and eosin (H&E) staining. Melatonin was found to reduce both paw thickness and the inflammation index in the mouse model, and melatonin also reduced the mRNA levels of interleukin-1 beta (IL-1β), IL-6 and NLR family pyrin domain containing 3 (NLRP3) inflammasome. To mimic gouty inflammation in vitro, mouse peritoneal macrophages were stimulated with lipopolysaccharides (LPS) plus MSU. Melatonin was revealed to reduce IL-1β secretion by stimulated macrophages. The mRNA expression levels of IL-1β and IL-6 were also inhibited by melatonin. Western blot analysis showed that the expression of NLRP3, caspase-1 and pro-IL-1β was also inhibited by melatonin. In conclusion, our study demonstrated that melatonin alleviated gouty inflammation in vivo and in vitro, and the underlying mechanism may involve inhibiting the assembly of the NLRP3 inflammasome.

Modified Simiaowan prevents articular cartilage injury in experimental gouty arthritis by negative regulation of STAT3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Modified Simiaowan (MSW) is a traditional Chinese medicine formula that is composed of six herbs. It has been widely used in the treatment of gouty arthritis.

AIM OF THE STUDY

This study was designed to investigate the effect of MSW on gouty arthritis and explore the possible mechanisms.

MATERIAL AND METHODS

The rat gouty arthritis model was established by intra-articular injection of Monosodium Urate (MSU) crystal, and then treated with MSW for 5 days. The perimeter of the knee joints was measured in a time-dependent manner and serum samples were collected for the detection of TNF-α, IL-1β, and IL-6 protein levels by ELISA. The protein expressions of MMP-3, TIMP-3, STAT3, and p-STAT3 in cartilage tissues and C28/I2 cells were detected by Western blot, and the levels of proteoglycan in primary chondrocytes and cartilage tissues were determined by toluidine blue staining. In addition, AG490 and IL-6 were used in vitro to explore the function of IL-6/STAT3 pathway in the protective effect of MSU.

RESULTS

MSW reduced the joint swelling rate in gouty arthritis model and inhibited MSU induced up-regulation of IL-1β, TNF-α, and IL-6 protein levels in serum and synovial fluid. IL-1β induced an increase in p-STAT3 and MMP-3 protein expression in C28/I2 cells, as well as a decrease in TIMP-3. MSW serum inhibited the protein expression changes induced by IL-1β in vitro. Furthermore, inhibition of STAT3 signaling negated the effect of MSW serum on p-STAT3, MMP-3, and TIMP-3 protein levels in C28/I2 cells. MSW also increased the content of proteoglycan significantly both in vivo and in vitro.

CONCLUSION

Our data indicated that MSW protected rats from MSU-induced experimental gouty arthritis and IL-1β/IL-6/STAT3 pathway played an essential role in the protective effect of MSU against GA.

Sesquiterpene lactones from Lychnophora species: Antinociceptive, anti-inflammatory, and antioxidant pathways to treat acute gout

ETHNOPHARMACOLOGICAL RELEVANCE

Lychnophora trichocarpha and Lychnophora passerina are species used in folk medicine to treat inflammation, pain, and rheumatism. Previous studies have demonstrated the anti-inflammatory effect of ethanol extracts of these species and identified that sesquiterpene lactones contribute to this activity.

AIM OF THE STUDY

Gout is an acute inflammatory arthritis caused by the deposition of monosodium urate (MSU) crystals in joints. Inflammation in joints induces oxidative stress in defense cells, releasing pro-inflammatory mediators. This study has three objectives: (1) to demonstrate the effects of sesquiterpene lactones lychnopholide and eremantholide C isolated from L. trichocarpha and goyazensolide isolated from L. passerina on arthritis induced by MSU crystals in C57BL6 mice; (2) to determine whether or not these compounds can inhibit the migration of neutrophils and the release of TNF-α and IL-1β cytokines in the inflammation region; and (3) to evaluate the effects of sesquiterpene lactones on the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the cartilage of C57BL/6 mice with gouty arthritis.

MATERIALS AND METHODS

The anti-inflammatory, antinociceptive, and antioxidant activities of sesquiterpene lactones in C57BL/6 mice with MSU crystal-induced arthritis were evaluated. In our experimental model, the mice were injected with MSU crystals in the tibiofemoral joint to induce arthritis and then treated with indomethacin, vitamin C, and sesquiterpene lactones. Nociception was evaluated before and after inflammation induction and treatments, neutrophil migration, IL-1β and TNF-α concentrations, and SOD and CAT activities.

RESULTS

Sesquiterpene lactones exerted an anti-inflammatory effect by inhibiting neutrophil migration and TNF-α production. These compounds also demonstrated antinociceptive and antioxidant activities.

CONCLUSION

Lychnopholide, eremantholide C, and goyazensolide improved the inflammation induced by MSU crystals by inhibiting the migration of neutrophils to the inflamed area and by blocking the release of the pro-inflammatory cytokine TNF-α. In addition, sesquiterpene lactones reduced oxidative stress by activating SOD and CAT. These results suggest that sesquiterpene lactones have anti-gout activity through the inflammation, pain, and oxidative stress pathways.

MiR-223-3p and miR-22-3p inhibit monosodium urate-induced gouty inflammation by targeting NLRP3

BACKGROUND

MicroRNAs (miRNAs) have been shown to play a crucial role in inflammation regulation; however, their relationship with inflammation in acute gouty arthritis has not been fully elucidated. Herein, we conducted a study to explore the regulatory roles of miR-223-3p and miR-22-3p in gouty-associated inflammation.

METHODS

In vitro and in vivo experiments were conducted to examine the molecular mechanisms of miRNA regulation in gouty inflammation. Dual-luciferase reporter assay was used to verify the direct target of miR-223-3p and miR-22-3p.

RESULTS

We found that miR-223-3p and miR-22-3p interacted with the 3' untranslated region segment of NLRP3 (nucleotide-binding domain leucine-rich repeat [NLR] and pyrin domain containing receptor 3) and inhibited its expression. A decreased expression of miR-223-3p and miR-22-3p was observed in both mice air pouch synovium and phorbol myristrate acetate-treated THP-1 cells stimulated with monosodium urate (P < .05). Compared with the negative control group, NLRP3 expression at the transcript and protein level in miR-223-3p and miR-22-3p overexpression group significantly decreased after 6 hours of monosodium urate treatment in vivo and in vitro (P < .05). The results of the dual-luciferase reporter assay demonstrated that miR-223-3p and miR-22-3p directly targeted NLRP3.

CONCLUSION

The findings of the present study show that miR-223-3p and miR-22-3p can reduce the inflammatory effects of gout by inhibiting the expression of NLRP3.

Baeckein E suppressed NLRP3 inflammasome activation through inhibiting both the priming and assembly procedure: Implications for gout therapy

BACKGROUND

Baeckein E (BF-2) was isolated from the aerial parts of Baeckea frutescens L., which has a long history of use in traditional medicine in Southeast Asia to treat inflammatory disease.

PURPOSE

BF-2 was identified to have inhibitory activity on nucleotide oligomerization domain (NOD)-like receptor protein-3 inflammasome (NLRP3) activation. This study aimed to investigate the related signaling cascade of BF-2 in both lipopolysaccharides (LPS)/ATP induced pyroptosis in J774A.1 macrophages and its application in a mouse model of gout induced by monosodium urate crystal (MSU).

METHODS

The effect of BF-2 on NLRP3 inflammasome activation and gouty arthritis was studied in J774A.1 macrophages and male C57BL/6 mice. The J774A.1 macrophages were primed with LPS and stained by propidium iodide (PI) for cell pyroptosis detection. A gout mouse model was established by subcutaneous injection of MSU crystals into the hind paw of C57BL/6 mice. Mice were then randomly divided into different groups. The concentrations of IL-1β and IL-18 in both J774A.1 macrophage and gout mouse model were analyzed by ELISA. The NLRP3 inflammasome related protein expression was detected by western blot analysis. The inhibitory effects of BF-2 on NLRP3 inflammasome assembly were analyzed by immunoprecipitation assay. The roles of BF-2 in mitochondrial damage were imaged by Mito Tracker Green and Mito Tracker Red probes. The inhibitory effects of BF-2 on ROS production were imaged by DCF (2',7'-dichlorofluorescein diacetate) probe.

RESULTS

The results demonstrated BF-2 could significantly suppress the cell pyroptosis and IL-1β secretion in macrophages. Furthermore, BF-2 significantly inhibited NLRP3 inflammasome activation and reduced ankle swelling in the gout mouse model. In detail, it alleviated mitochondrial damage mediated oxidative stress and inhibited the assembly of NLRP3 inflammasome by affecting the binding of pro-Caspase 1 and ASC. Moreover, BF-2 blocked NLRP3 activation by inhibiting the MAPK/NF-κB signaling pathways.

CONCLUSIONS

Results demonstrated BF-2 inhibited NLRP3 inflammasome activation in both LPS primed macrophages and mouse model of gout through blocking MAPK/NF-κB signaling pathway and mitochondrial damage mediated oxidative stress. This study strongly suggests BF-2 could be a promising drug candidate against inflammatory diseases associated with NLRP3 inflammasome activation.

Curcumin analogue AI-44 alleviates MSU-induced gouty arthritis in mice via inhibiting cathepsin B-mediated NLRP3 inflammasome activation

NOD-like receptors (NLRs), as a part of intracellular pattern recognition receptors (PRR), are important regulators in innate immune system. The NLRP3 inflammasome which is a member of NLRs has been linked to several human inflammatory diseases. Gouty arthritis is triggered when the deposition of monosodium urate (MSU) crystals in joints induces acute inflammation characterized by the recruitment of macrophages and neutrophils. In this study, we explored the curcumin analogue AI-44 alleviated the gouty arthritis in mice via suppressing MSU engaging NLRP3 inflammasome activation. Furthermore, we demonstrated that AI-44 inhibited the interaction of cathepsin B and NLRP3 to prevent the activation of NLRP3 inflammasome. Moreover, we found AI-44 inhibited the enzyme activity of cathepsin B and bound to the key residue E122 in cytoplasm but not in lysosome. Collectively, these data suggest that AI-44 is a novel drug candidate for the treatment of gouty arthritis through targeting cathepsin B and inhibiting NLRP3 inflammasome activation.

Total glucosides of paeony protects THP-1 macrophages against monosodium urate-induced inflammation via MALAT1/miR-876-5p/NLRP3 signaling cascade in gouty arthritis

BACKGROUND

Monosodium urate (MSU)-mediated inflammatory response is a crucial inducing factor in gouty arthritis. Here, we explored the underlying mechanism of total glucosides of paeony (TGP) in MSU-induced inflammation of THP-1 macrophages in gouty arthritis.

METHODS

3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect cell viability. Enzyme-linked immunosorbent assay (ELISA) was utilized to measure the production of interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α). Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot assay were conducted to determine RNA and protein expression. Dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull down assay were used to confirm the interaction between miR-876-5p and MALAT1 or NLR family pyrin domain containing 3 (NLRP3).

RESULTS

MSU-induced damage and inflammatory response in THP-1 macrophages were alleviated by the treatment of TGP in a dose-dependent manner. Overexpression of NLRP3 or MALAT1 reversed the protective effects of TGP in MSU-induced THP-1 macrophages. The binding relation between miR-876-5p and MALAT1 or NLRP3 was identified in THP-1 macrophages. MALAT1 up-regulated the expression of NLRP3 by sponging miR-876-5p in THP-1 macrophages. TGP suppressed MSU-induced inflammation in THP-1 macrophages through regulating MALAT1/miR-876-5p/NLRP3 axis. TGP suppressed MSU-induced activation of TLR4/MyD88/NF-κB pathway through regulating MALAT1/miR-876-5p/NLRP3 axis.

CONCLUSION

In conclusion, TGP suppressed MSU-induced inflammation in THP-1 macrophages through regulating MALAT1/miR-876-5p/NLRP3 axis and TLR4/MyD88/NF-κB pathway, suggesting that TGP was a promising active ingredient for gouty arthritis treatment.

Tripterine ameliorates monosodium urate crystal-induced gouty arthritis by altering macrophage polarization via the miR-449a/NLRP3 axis

OBJECTIVE

Tripterine (Trip) is frequently applied to alleviate inflammation in various diseases such as rheumatoid arthritis. Macrophages have both anti-inflammatory and pro-inflammatory functions. However, whether Trip can inhibit cell inflammation in gouty arthritis (GA) remains undiscovered and whether the mechanism involved in macrophage polarization is also undetermined. This paper aims to study the effects of Trip on inflammation and macrophage polarization in GA.

METHODS

Monosodium urate (MSU) crystals were used to establish GA mouse models, and bone marrow-derived macrophages (BMDMs) were induced to construct GA cell models. Pretreatments of Trip and injection of Antagomir-449a/Agomir-449a were performed on mice for 6 days. The effects of Trip and miR-449 on toe swelling, joint damage of GA mouse were examined. The alternations on cell morphology, cell proliferation marker Ki67, inflammatory cytokines, NLRP3 inflammasome, and NF-κB signaling-related proteins were also determined both in vivo and in vitro. Dual-luciferase reporter gene assay and RIP assay were adopted to estimate the targeting relationship between miR-449a and NLRP3.

RESULTS

GA mouse model had increased M1 macrophage, intensified inflammation response, along with suppressed miR-449a expression. Following administration of Trip attenuated cell inflammation, promoted macrophage polarize to M2 phenotype, elevated miR-449a expression, repressed the phosphorylation levels of NF-κB signaling-related proteins, and diminished IκBα expression in vivo and in vitro. However, inhibition of miR-449a hindered the favorable effect of Trip on GA and increased NLRP3 inflammasome expression. MiR-449a directly targeted NLRP3. Overexpression of NLRP3 partially eliminated the biological effects of miR-449a agonist.

CONCLUSION

Trip regulates macrophage polarization through miR-449a/NLRP3 axis and the STAT3/NF-κB pathway to mitigate GA. The elucidation on the molecular mechanism of Trip in GA may provide theoretical guidance for clinical therapy of GA.

Design, synthesis and evaluation of 3-amide-5-aryl benzoic acid derivatives as novel P2Y14R antagonists with potential high efficiency against acute gouty arthritis

P2Y₁₄ nucleotide receptor plays important roles in series of physiological and pathologic events especially associated with immune and inflammation. Based on the 3-amide benzoic acid scaffold reported by our group previously, a series of 5-aryl-3-amide benzoic acid derivatives were designed as novel P2Y₁₄ antagonists with improved pharmacokinetic properties. Among which compound 11m showed most potent P2Y₁₄ antagonizing activity with an IC₅₀ value of 2.18 nM, furnishing greatly improved water solubility and bioavailability compared with PPTN. In MSU-induced acute gouty arthritis model in mice, 11m exerted promising in vivo efficacy in alleviating mice paw swelling and inflammatory infiltration. Mechanistically, compound 11m notably blocked pyroptosis of macrophages through inhibiting NLRP3 inflammasome activation. This work may contribute to the identification of potential therapeutic agents to intervene in acute gouty arthritis.

Celastrol ameliorates Propionibacterium acnes/LPS-induced liver damage and MSU-induced gouty arthritis via inhibiting K63 deubiquitination of NLRP3

BACKGROUND

Celastrol, a pentacyclic triterpenoid quinonemethide isolated from several spp. of Celastraceae family, exhibits anti-inflammatory activities in a variety of diseases including arthritis.

PURPOSE

This study aims to investigate whether the inhibition of NLRP3 inflammasome is engaged in the anti-inflammatory activities of celastrol and delineate the underlying mechanism.

METHODS

The influence of celastrol on NLRP3 inflammasome activation was firstly studied in lipopolysaccharide (LPS)-primed mouse bone marrow-derived macrophages (BMDMs) and phorbol 12-myristate 13-acetate (PMA)-primed THP-1 cells treated with nigericin. Reconstituted inflammasome was also established by co-transfecting NLRP3, ASC, pro-caspase-1 and pro-IL-1β in HEK293T cells. The changes of inflammasome components including NLRP3, ASC, pro-caspase-1/caspase-1 and pro-IL-1β/IL-1β were examined by enzyme-linked immunosorbent assay (ELISA), western blotting and immunofluorescence. Furthermore, Propionibacterium acnes (P. acnes)/LPS-induced liver injury and monosodium urate (MSU)-induced gouty arthritis in mice were employed in vivo to validate the inhibitory effect of celastrol on NLRP3 inflammasome.

RESULTS

Celastrol significantly suppressed the cleavage of pro-caspase-1 and pro-IL-1β, while not affecting the protein expressions of NLRP3, ASC, pro-caspase-1 and pro-IL-1β in THP-1 cells, BMDMs and HEK293T cells. Celastrol suppressed NLRP3 inflammasome activation and alleviated P. acnes/LPS-induced liver damage and MSU-induced gouty arthritis. Mechanism study revealed that celastrol could interdict K63 deubiquitination of NLRP3, which may concern interaction of celastrol and BRCA1/BRCA2-containing complex subunit 3 (BRCC3), and thereby prohibited the formation of NLRP3, ASC and pro-caspase-1 complex to block the generation of mature IL-1β.

CONCLUSION

Celastrol suppresses NLRP3 inflammasome activation in P. acnes/LPS-induced liver damage and MSU-induced gouty arthritis via inhibiting K63 deubiquitination of NLRP3, which presents a novel insight into inhibition of celastrol on NLRP3 inflammasome and provides more evidences for its application in the therapy of inflammation-related diseases.

The Extraction Solvent Influences the Anti-Inflammatory Effects of Jakyakgamcho-Tang in Lipopolysaccharide-Stimulated Macrophages and Mice with Gouty Arthritis

Jakyakgamcho-Tang (JGT) is a traditional medicine used to treat muscular tension, spasm, and pain. Several studies have reported its clinical use as an anti-inflammatory and in gynaecological treatment. This study aimed to compare the anti-inflammatory effects of JGT according to extraction solvent, water (JGTW) and 30% EtOH (JGTE) on lipopolysaccharide (LPS)—stimulated macrophages and in mice with monosodium urate (MSU)—induced gouty arthritis. We evaluated the production of inflammatory mediators and cytokines and the expression of inducible nitric oxide (iNOS) and cyclooxygenase-2 (COX-2) in RAW 264.7 cells. We also examined oedema, pain, and inflammation in MSU-induced mice by measuring affected hind paw swelling, weight-bearing, pro-inflammatory cytokines levels, and myeloperoxidase (MPO) activity. In LPS-stimulated RAW264.7 cells, JGTW and JGTE significantly decreased prostaglandin (PG) E2(PGE2) production via suppressing COX-2 expression and cytokines interleukin-1β and interleukin-6. Only JGTE reduced the production of NO and cytokines and the mRNA levels of iNOS and cytokines. In MSU-induced mice, JGTE and JGTW efficiently decreased paw swelling and attenuated joint pain. JGTE (200 and 300 mg/kg) effectively suppressed inflammation by downregulating pro-inflammatory cytokines (tumour necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6) and MPO activity, which were only slightly reduced by JGTW. Our data demonstrate the anti-inflammatory activity of JGT in macrophage and gouty arthritis animal models and show that JGTE is more effective than JGTW at lower concentrations.

Acute Gouty Arthritis During Favipiravir Treatment for Coronavirus Disease 2019

A 42-year-old man exhibiting hypoxia was diagnosed with coronavirus disease 2019. He had medical histories of type 2 diabetes, hyperlipidemia, hyperuricemia, and gout attack. He received favipiravir for compassionate use for 14 days. Subsequently, he showed increased uric acid levels and developed acute gouty arthritis. Favipiravir may induce not only hyperuricemia but also acute gouty arthritis. It should therefore be used with caution in patients with a history of gout and those with hyperuricemia, especially when used at a higher dose and for a longer duration than is typical.

IL-33 enhances macrophage release of IL-1β and promotes pain and inflammation in gouty arthritis

OBJECTIVE

To investigate the role of IL-33 in gouty arthritis.

MATERIAL

174 Balb/c (wild-type) and 54 ST2^-/- mice were used in this study. In vitro experiments were conducted in bone marrow-derived macrophages (BMDMs). Synovial fluid samples from gouty arthritis (n = 7) and osteoarthritis (n = 8) hospital patients were used to measure IL-33 and sST2 levels.

METHODS

Gout was induced by injection of monosodium urate (MSU) crystals in the knee joint of mice. Pain was determined using the electronic von Frey and static weight bearing. Neutrophil recruitment was determined by H&E staining, Rosenfeld staining slides, and MPO activity. ELISA was used for cytokine and sST2 measurement. The priming effect of IL-33 was determined in BMDM.

RESULTS

Synovial fluid of gout patients showed higher IL-33 levels and neutrophil counts than osteoarthritis patients. In mice, the absence of ST2 prevented mechanical pain, knee joint edema, neutrophil recruitment to the knee joint, and lowered IL-1β and superoxide anion levels. In macrophages, IL-33 enhanced the release of IL-1β and TNF-α, and BMDMs from ST2^-/- showed reduced levels of these cytokines after stimulus with MSU crystals.

CONCLUSION

IL-33 mediates gout pain and inflammation by boosting macrophages production of cytokines upon MSU crystals stimulus.

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.

Characteristics of voltage-gated potassium currents in monosodium urate induced gouty arthritis in mice

OBJECTIVE

To evaluate the role of K⁺ channels in pain following gouty arthritis.

METHODS

The model of acute gouty arthritis was induced by monosodium urate (MSU) in mice. The swelling degree was determined by measuring the circumference of the ankle joint. Mechanical hyperalgesia was detected by von Frey filaments. Two types of K⁺ currents, A-type currents (I_A) and delayed rectifier currents (I_K), were recorded in dorsal root ganglion (DRG) neurons using patch-clamp techniques.

RESULTS

The swelling degree reached its maximum at 10 h and the minimum pain threshold was maintained between 8 and 48 h after MSU treatment in mice. The amplitudes of I_A and I_K in DRG neurons were moderately increased on day 1 after MSU treatment, and then, they were gradually decreased with times and reached their minimums on day 4 (for I_A) or 5 (for I_K). Compared with control group, the activation curve of I_A was significantly shifted to more positive potential and the recovery time of I_A from inactivation was markedly prolonged, but inactivation and frequency dependence of I_A appeared unaffected in MSU-treated group. Additionally, no change was observed in the activation curve of I_K after MSU treatment. The excitability was significantly higher in the MSU group than in the control group.

CONCLUSIONS

MSU-induced gout pain may be related to the hyperexcitability of DRG neurons elicited by decreasing K⁺ currents.

LC-MS Analysis of Serum for the Metabolomic Investigation of the Effects of Pulchinenoside b4 Administration in Monosodium Urate Crystal-Induced Gouty Arthritis Rat Model

Gouty arthritis (GA) is commonly caused by deposition of monosodium urate (MSU) crystals within the joint capsule, bursa, cartilage, bone, or other periarticular tissues after chronic hyperuricemia. Clinically, GA is characterized by acute episodes of joint inflammation, which is most frequently encountered in the major joints, and also has a significant impact on quality of life. Pulchinenoside b4(P-b4) has a wide range of biological activities, including antitumor, anti-inflammatory, antiviral and immunomodulatory activities. Currently, the anti-GA activity and metabolomic profiles after being treated by P-b4 have not been reported. In this paper, for the first time, we have performed a non-targeted metabolomics analysis of serum obtained from an MSU crystal-induced GA rat model intervened by P-b4, using ultra-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry. In this study, the main pharmacodynamics of different dosing methods and dosages of P-b4 was firstly investigated. Results have shown that P-b4 possesses high anti-inflammatory activity. These results demonstrated changes in serum metabolites with 32 potential biomarkers. Arachidonic acid, sphingolipid, and glycerophospholipid metabolism are considered to be the most relevant metabolic pathway with P-b4 treatment effect in this study. Moreover, the changes of metabolites and the self-extinction of model effects within 24 h reveals important information for GA diagnostic criteria: The regression of clinical symptoms or the decline of some biochemical indicators cannot be regarded as the end point of GA treatment. Furthermore, our research group plans to conduct further metabolomics research on the clinical course of GA.

Termipaniculatones A-F, chalcone-flavonone heterodimers from Terminthia paniculata, and their protective effects on hyperuricemia and acute gouty arthritis

Terminthia paniculata (Sanyeqi) is widely used for treating inflammation and rheumatic arthritis in the folk areas of Yunnan province, China. Its total extract was first revealed with xanthine oxidase (XO) inhibitory activity in vitro and anti-hyperuricemic effect in vivo. Bioassay-guided separation on Fr. A5 yielded six chalcone-flavonone heterodimers, termipaniculatones A-F. Their structures were elucidated based on extensive spectroscopic analyses involving HRESIMS, 1D and 2D NMR, UV, IR and [α]_D, and the absolute configuration of termipaniculatone F was verified by ECD calculation. Termipaniculatones A and E showed obvious XO inhibitory activity with IC₅₀ values of 55.6 and 89.5 μM, respectively, which took effects via a mix-type mode. A molecular modeling study revealed that termipaniculatone A was well located into the active site of XO by interacting with Glu802, Arg880, Thr1010 and Val1011 residues. Termipaniculatone A showed anti-hyperuricemic effects by decreasing serum uric acid levels and inhibiting XO activity in both serum and liver on potassium oxonate (PO)-induced hyperuricemia mice, and anti-inflammatory activity through alleviating paw swelling on monosodium urate (MSU)-induced mice, at the concentration of 20 mg/kg. This is the first time to reveal the anti-hyperuricemic and anti-acute gouty arthritis potency of T. paniculata and the characteristic biflavonoids as active constituents, which provides valuable information for searching new XO inhibitors from natural sources.

Protective effects of Rhizoma smilacis glabrae extracts on potassium oxonate- and monosodium urate-induced hyperuricemia and gout in mice

BACKGROUND

Rhizoma smilacis glabrae (RSG, tufuling) has been widely used in traditional Chinese medicine for deoxidation, dampness relief, and easing joint movement. The chemical composition of RSG has been systematically confirmed, and some of its compounds have been revealed to possess antioxidant, anti-inflammatory, immunomodulatory, hypouricemic, and hepatoprotective effects.

PURPOSE

We aimed to clarify whether a RSG extract attenuates hyperuricemia, paw edema, and renal injury in mice with potassium oxonate (PO)- and monosodium urate (MSU)-induced chronic hyperuricemia and gout.

METHODS

RSG water extract was obtained and analyzed by HPLC-DAD-MS/MS. To establish a murine model with chronic hyperuricemia and gout, PO was orally administered daily from day 0 to day 24, whereas MSU was injected into the tibiotarsal joint on day 21. The mice in the drug intervention groups were treated once daily with doses of allopurinol or RSG extract from day 21 to day 24. The diameter of the ankle joints was measured with calipers. Serum TNF-α and IL-1β concentrations, hepatic XOD activity, and uric acid, creatinine, and blood urea nitrogen (BUN) levels were also determined. The right kidney and articular cavities were fixed, cut into sections, and stained with hematoxylin and eosin.

RESULTS

Nine compounds in the RSG water extract were unambiguously identified as 5-O-caffeoylshikimic acid, neoastilbin, astilbin, taxifolin, neoisoastilbin, isoastilbin, engeletin, isoengeletin, and trans-resveratrol. The RSGE treatment dose-dependently reduced PO- and MSU-induced paw edema, serum TNF-α, IL-1β, IL-6, IL-12, uric acid, and BUN, while significantly elevated serum IL-10, urinary uric acid and creatinine levels as compared with the respective values in the hyperuricemic and gouty mice group (vehicle group). Moreover, the hepatic XOD activity was dose-dependently reduced by the RSGE treatment. In addition, RSGE treatment not only ameliorated the infiltration of inflammatory cells, tubular dilation and vacuole formation in renal tubular, but also improved the synovial hyperplasia, reduced inflammatory cells infiltration into the synovium, and diminished the erosive damage in the cartilage.

CONCLUSION

The murine model with chronic hyperuricemia and gout be built in present study is consistent with the clinical symptoms of patients with long-standing hyperuricemia and acute gouty arthritis. RSG water extract has potent efficacy in ameliorating murine hyperuricemia and gout induced by PO and MSU.