BRD4 promotes gouty arthritis through MDM2-mediated PPARγ degradation and pyroptosis.

BACKGROUND: Gouty arthritis (GA) is characterized by monosodium urate (MSU) crystal accumulation that instigates NLRP3-mediated pyroptosis; however, the underlying regulatory mechanisms have yet to be fully elucidated. The present research endeavors to elucidate the regulatory mechanisms underpinning this MSU-induced pyroptotic cascade in GA. METHODS: J774 cells were exposed to lipopolysaccharide and MSU crystals to establish in vitro GA models, whereas C57BL/6 J male mice received MSU crystal injections to mimic in vivo GA conditions. Gene and protein expression levels were evaluated using real-time quantitative PCR, Western blotting, and immunohistochemical assays. Inflammatory markers were quantified via enzyme-linked immunosorbent assays. Pyroptosis was evaluated using immunofluorescence staining for caspase-1 and flow cytometry with caspase-1/propidium iodide staining. The interaction between MDM2 and PPARγ was analyzed through co-immunoprecipitation assays, whereas the interaction between BRD4 and the MDM2 promoter was examined using chromatin immunoprecipitation and dual-luciferase reporter assays. Mouse joint tissues were histopathologically evaluated using hematoxylin and eosin staining. RESULTS: In GA, PPARγ was downregulated, whereas its overexpression mitigated NLRP3 inflammasome activation and pyroptosis. MDM2, which was upregulated in GA, destabilized PPARγ through the ubiquitin-proteasome degradation pathway, whereas its silencing attenuated NLRP3 activation by elevating PPARγ levels. Concurrently, BRD4 was elevated in GA and exacerbated NLRP3 activation and pyroptosis by transcriptionally upregulating MDM2, thereby promoting PPARγ degradation. In vivo experiments showed that BRD4 silencing ameliorated GA through this MDM2-PPARγ-pyroptosis axis. CONCLUSION: BRD4 promotes inflammation and pyroptosis in GA through MDM2-mediated PPARγ degradation, underscoring the therapeutic potential of targeting this pathway in GA management.

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

BACKGROUND: Gout is caused by monosodium urate (MSU) crystals deposition to trigger immune response. A recent study suggested that inhibition of Class I Histone deacetylases (HDACs) can significantly reduce MSU crystals-induced inflammation. However, which one of HDACs members in response to MSU crystals was still unknown. Here, we investigated the roles of HDAC3 in MSU crystals-induced gouty inflammation. METHODS: Macrophage specific HDAC3 knockout (KO) mice were used to investigate inflammatory profiles of gout in mouse models in vivo, including ankle arthritis, foot pad arthritis and subcutaneous air pouch model. In the in vitro experiments, bone marrow-derived macrophages (BMDMs) from mice were treated with MSU crystals to assess cytokines, potential target gene and protein. RESULTS: Deficiency of HDAC3 in macrophage not only reduced MSU-induced foot pad and ankle joint swelling but also decreased neutrophils trafficking and IL-1ß release in air pouch models. In addition, the levels of inflammatory genes related to TLR2/4/NF-κB/IL-6/STAT3 signaling pathway were significantly decreased in BMDMs from HDAC3 KO mice after MSU treatment. Moreover, RGFP966, selective inhibitor of HDAC3, inhibited IL-6 and TNF-α production in BMDMs treated with MSU crystals. Besides, HDAC3 deficiency shifted gene expression from pro-inflammatory macrophage (M1) to anti-inflammatory macrophage (M2) in BMDMs after MSU challenge. CONCLUSIONS: Deficiency of HDAC3 in macrophage alleviates MSU crystals-induced gouty inflammation through inhibition of TLR2/4 driven IL-6/STAT3 signaling pathway, suggesting that HDAC3 could contribute to a potential therapeutic target of gout.

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-1ß, TNF-α, IL-12, and iNOS) and M2-related factors (Mgl1, Mgl2, Pgc1-ß, 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.

Potential Anti-Gouty Arthritis of Citronella Essential Oil and Nutmeg Essential Oil through Reducing Oxidative Stress and Inhibiting PI3K/Akt/mTOR Activation-Induced NLRP3 Activity.

Citronella and Nutmeg are two common spices used for seasoning and medicinal purposes, both of which have significant economic value. This study aimed to investigate whether Citronella essential oil and Nutmeg essential oil (NEO) can ameliorate monosodium urate (MSU)-induced gouty arthritis in rats and the potential mechanisms. The results showed that CEO and NEO reduced swelling and redness at joint sites, inhibited neutrophil infiltration, and limited proinflammatory mediator secretion in mice with MSU-induced gouty arthritis. Based on the results of network pharmacology, molecular docking, and western blotting, CEO and NEO may exert anti-gouty arthritis effects by reducing the expression of reactive oxygen species and oxidative stress and downregulating the phosphorylation of the PI3K/AKT/mTOR signaling pathway, thereby inhibiting the production of the NLRP3 inflammasome and inhibiting the production of inflammatory cytokines. Therefore, these two essential oils show potential for use as adjuvant treatments for gouty arthritis in specific aromatherapy products or food seasonings.

[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)-1ß, 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.

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)-1ß from cytoplasm to cell supernatant. Geraniin also inhibited the expression of caspase-1 p20, IL-1ß 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-1ß, 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-1ß 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-1ß release to provide potential insights for gouty arthritis targeted therapy.

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-1ß, 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-1ß 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.

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-1ß (IL-1ß), 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-1ß, 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)-1ß, 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-1ß, 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-1ß 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.

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.

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.

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-1ß, 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.

Resveratrol alleviates MSU-induced gouty arthritis in rats through inhibition of HIF-1α- and NLRP3-derived IL-1ß 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-1ß secretion. Furthermore, resveratrol and the HIF-1α inhibitor PX478 both inhibited the expression of the NLRP3 inflammasome, IL-1ß, and HIF-1α. This study demonstrated that resveratrol significantly improved the symptoms of acute gouty arthritis and its potential mechanism may be IL-1ß reduction via HIF-1α modulation and inhibition of NLRP3 inflammasome activation. Our study might offer a novel sight for the treatment of 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.

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.

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-1ß 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-1ß 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.

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.

Tissue lipidomics, network pharmacology, and molecular docking to explore the therapeutic mechanism of anthocyanins from Lycium ruthenicum Murr. against gouty arthritis.

Lycium ruthenicum Murr. (LR) has long been used as a unique nutritional and medicinal food to treat various diseases such as gouty arthritis. However, although recently the literature has focused on the protective roles of LR anthocyanins on gouty arthritis, there is no relevant research from a holistic perspective of lipid metabolism to study their anti-gout effects. In this study, a combined tissue lipidomics, network pharmacology, and molecular docking approach was performed to investigate the intervention mechanism of LR anthocyanins against a monosodium urate (MSU)-induced gout mouse model. 54 gout-related lipid markers were identified via lipidomic profiling of the mouse knee joint, including glycerophospholipids, sphingolipids, glycerolipids, and plasmalogens. Integrating with pathway analysis, network pharmacology, and molecular docking, the potential targets of LR anthocyanins for treating gouty arthritis were predicted, while pathways in cancer, prostate cancer, sphingolipid signaling, choline metabolism in cancer, arachidonic acid metabolism, and ovarian steroidogenesis were involved as shared critical pathways of lipidomic analysis and network pharmacology. Furthermore, the binding sites and patterns of 3 active components and 4 core targets with the lowest binding energies were explored. Western blotting was finally used to verify the expression levels of 4 core proteins: MMP2, MMP9, MAP2K1, and MAPK14. These results provide new insights into our understanding of gouty arthritis and the anti-gout mechanism of LR anthocyanins.