Mechanisms of inflammation in gout

Anti-inflammatory effects of MerTK by inducing M2 macrophage polarization via PI3K/Akt/GSK-3β pathway in gout

Mer tyrosine kinase (MerTK) has been found to regulate the secretion of inflammatory factors and exert immunosuppressive effects, but its role in gout remains unclear. In this study, we aimed to clarify the immnue effects of MerTK in gout. MerTK in synovium or serum of gout patients was determined by immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), and real-time quantitative polymerase chain reaction (RT-qPCR). In monosodium urate (MSU)-induced gout mice, the effect of MerTK inhibitor (UNC2250) on inflammation and polarization was also assessed. After inhibition, knockdown or overexpression of MerTK, inflammatory response and polarization level in THP1-derived macrophages were evaluated by RT-qPCR and flow cytometry. Regulation of MerTK inhibitors on mitochondrial function and downstream pathway in THP1-derived macrophages were detected. MerTK in synovium and serum of gout patients were increased. MerTK inhibitor stimulated the inflammation and M1 polarization in MSU-induced gout mice. MerTK inhibition, knock-down, or overexpression affected inflammatory response, polarization and mitochondrial function in vitro in gout model. The PI3K/Akt/GSK-3β pathway was identified to reduce after MerTK inhibition and the relevant results were as expected, validated by knock-down or overexpressing MerTK. In conclusion, MerTK was detected to increase in both gout patients and model. MerTK influenced inflammatory response and polarization markers through PI3K/Akt/GSK-3β pathway. Interfering MerTK/PI3K/Akt/GSK-3β axis may provide a new therapeutic target for gout.

The Prevalence and Factors Associated with Coronary Heart Disease in Patients with Gout

Gout is associated with increased risk of cardiovascular disease (CVD) morbidity and mortality. Therefore, an association between coronary heart disease (CHD) and gout deserves careful examination.

AIM

. The aim of this study was to determine the prevalence of CHD and factors associated with CHD in patients (pts) with gout.

MATERIALS AND METHODS

. The study involved 286 male patients with gout, age 51.2 [42.8; 59.4] years (ys), disease duration 6.2 [3.8; 12.1] ys. All patients underwent standard clinical examination screening traditional risk factors (TRFs) of CVDs. We estimated the adjusted odds ratio (OR) and 95% confidence interval (95% CI).

RESULTS

. CHD was found in 111 out of the 286 pts (38.8%), MI had a history in 29.7%. Compared to individuals with CHD, participants without CHD were older (56.7[52.1; 61.1] vs 46.2[40.6; 53.4] ys), had longer duration of gout (9.3[4.7; 15.1] vs 5.6[3.3; 9.7] ys) (for all p < 0.05). Abdominal obesity (OR, 3.6; 95% CI, 1.2-10.9), family history of CHD (OR, 2.2; 95% CI, 1.3-3.7), disease duration of gout more 10 ys (OR, 2.8; 95% CI, 1.6-4.7), age of gout onset < 35 ys (OR, 5.5; 95% CI, 2.6-11.7), intraosseous tophi (OR, 3.03; 95% CI, 1.8-5.01), nephrolithiasis (OR, 1.7; 95% CI, 1.04-3.04), renal failure (OR, 5.6; 95% CI, 2.7-11.4), serum total cholesterol (TC), (OR, 1.6; 95% CI, 1.0-2.8), serum creatinine (OR, 2.5; 95% CI, 1.2-5.1), increased the risk for CHD in patients with a gout.

CONCLUSIONS

. The prevalence of CHD was 38.8% among individuals with gout (one-third of patients had a history of MI 29.7%). Our study showed that both TRFs of CVD and the severity of gout and a history of renal failure contribute to the development of CHD in patients with gout.

Associations of oxidative balance score with hyperuricemia and gout among American adults: a population-based study

Objective

The current study aimed to assess the relationships between oxidative balance score (OBS) and OBS subclasses (dietary and lifestyle OBS) with risks of hyperuricemia (HUA) and gout among American adults.

Methods

Participants in the National Health and Nutrition Examination Survey from 2007 to 2018 were initially recruited and then the final sample was restricted to adults without missing values about serum uric acid, gout, OBS, and covariates. Rao-Scott adjusted chi-square test and analysis of variance were utilized to compare the baseline characteristics in adults of different quartiles of OBS, while the weighted stepped logistic regression models were used to explore the associations of overall, dietary, and lifestyle OBS with the risks of HUA and gout. Weighted restricted cubic spline analyses were conducted to explore the nonlinear dose-response associations.

Results

The final sample consisted of 22,705 participants aged 20 years and older, which was representative of approximately 197.3 million non-institutionalized American adults. HUA and gout prevalence decreased with OBS quartiles. Compared with adults in the first quartile of OBS, those in the second (OR: 0.85, 95% CI: 0.72-0.99), third (OR: 0.71, 95% CI: 0.58-0.85), and fourth (OR: 0.48, 95% CI: 0.38-0.61) quartiles of OBS had reduced risks of hyperuricemia. Similarly, adults in the second (OR: 0.70, 95% CI: 0.51-0.97) quartile of OBS was associated with lower gout risk in comparison to adults in the lowest quartile. Regarding OBS subclasses, dietary and lifestyle OBS were both negatively correlated with the risk of HUA, and only higher lifestyle OBS was significantly associated with lower gout risk. Furthermore, the subgroup analyses and interaction effects also substantiated similar effects. Significant nonlinear dose-response relationships were observed between overall, dietary, and lifestyle OBS with HUA risk as well as that of lifestyle OBS with gout risk.

Conclusion

This study strongly suggests the significant negative associations of OBS with HUA and gout in American adults and provides a dietary and lifestyle guideline to reduce the risks.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The NADase CD38 is a central regulator in gouty inflammation and a novel druggable therapeutic target

OBJECTIVES

Cellular NAD+ declines in inflammatory states associated with increased activity of the leukocyte-expressed NADase CD38. In this study, we tested the potential role of therapeutically targeting CD38 and NAD+ in gout.

METHODS

We studied cultured mouse wild type and CD38 knockout (KO) murine bone marrow derived macrophages (BMDMs) stimulated by monosodium urate (MSU) crystals and used the air pouch gouty inflammation model.

RESULTS

MSU crystals induced CD38 in BMDMs in vitro, associated with NAD+ depletion, and IL-1β and CXCL1 release, effects reversed by pharmacologic CD38 inhibitors (apigenin, 78c). Mouse air pouch inflammatory responses to MSU crystals were blunted by CD38 KO and apigenin. Pharmacologic CD38 inhibition suppressed MSU crystal-induced NLRP3 inflammasome activation and increased anti-inflammatory SIRT3-SOD2 activity in macrophages. BMDM RNA-seq analysis of differentially expressed genes (DEGs) revealed CD38 to control multiple MSU crystal-modulated inflammation pathways. Top DEGs included the circadian rhythm modulator GRP176, and the metalloreductase STEAP4 that mediates iron homeostasis, and promotes oxidative stress and NF-κB activation when it is overexpressed.

CONCLUSIONS

CD38 and NAD+ depletion are druggable targets controlling the MSU crystal- induced inflammation program. Targeting CD38 and NAD+ are potentially novel selective molecular approaches to limit gouty arthritis.

Mechanistic insights into the C-type lectin receptor CLEC12A-mediated immune recognition of monosodium urate crystal

CLEC12A, a member of the C-type lectin receptor family involved in immune homeostasis, recognizes MSU crystals released from dying cells. However, the molecular mechanism underlying the CLEC12A-mediated recognition of MSU crystals remains unclear. Herein, we reported the crystal structure of the human CLEC12A-C-type lectin-like domain (CTLD) and identified a unique "basic patch" site on CLEC12A-CTLD that is necessary for the binding of MSU crystals. Meanwhile, we determined the interaction strength between CLEC12A-CTLD and MSU crystals using single-molecule force spectroscopy. Furthermore, we found that CLEC12A clusters at the cell membrane and seems to serve as an internalizing receptor of MSU crystals. Altogether, these findings provide mechanistic insights for understanding the molecular mechanisms underlying the interplay between CLEC12A and MSU crystals.

Trends in healthcare utilization by patients with gout: A cross-sectional study using Health Insurance Review and Assessment Service data

This study aimed to analyze the distribution of gout patients and the utilization of healthcare services in South Korea to provide valuable recommendations to clinicians and policymakers. A cross-sectional study was conducted. Claims data from the Health Insurance Review and Assessment Service spanning 2010 to 2019 were utilized, and a sample of 69,680 patients was included in the study. The incidence of gout was observed to be high in male patients over the age of 40, with most patients receiving outpatient care for gout management. Nonsteroidal anti-inflammatory drugs and urate-lowering agents were the most frequently prescribed medications, with prescriptions for colchicine and febuxostat increasing among urate-lowering agents. Musculoskeletal disorders were found to be the most common comorbidities among gout patients. Although the total costs of gout management increased, there was no significant increase in cost per patient. This study provides insights into the current state of healthcare utilization for gout patients in South Korea and trends in the disease burden and use of medications. The findings have crucial implications for clinicians and policymakers involved in decision-making regarding the management and treatment of gout.

The Impact of Different Intensities of Physical Activity on Serum Urate and Gout: A Mendelian Randomization Study

Physical activity is a potential protective factor against gout, but the role of exercise intensity in this context remains unclear. To overcome the limitations of observational studies in causal inference, this study employed a two-sample Mendelian randomization approach to explore the impact of different genetically proxied/predicted intensities of physical activity on serum urate concentration and the incidence of gout. Our data related to physical activity, serum urate, and gout were obtained from the UK Biobank, the Global Urate Genetics Consortium (GUGC), and the FinnGen dataset, respectively. Walking was included as representative of typical low-intensity physical activity in the analysis, and the other two types were moderate and vigorous physical activities. The estimation methods we used included the inverse-variance-weighted (IVW) method, MR-Egger regression, weighted-median method, simple-mode method, and weighted-mode method. Sensitivity analyses involved Rucker's framework, Cochran's Q test, funnel plots, MR-PRESSO outlier correction, and leave-one-out analysis. We found suggestive evidence from the inverse-variance-weighted method that moderate physical activity was a potential factor in reducing the incidence of gout (OR = 0.628, p = 0.034), and this association became more substantial in our subsequent sensitivity analysis (OR = 0.555, p = 0.006). However, we observed no distinctive effects of physical activity on serum urate concentration. In conclusion, our study supports some findings from observational studies and emphasizes the preventive role of moderate physical activity against gout. Given the limitations of the existing datasets, we call for future reexamination and expansion of our findings using new GWAS data.

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.

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

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

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.

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

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

Targeting CD44 Receptor Pathways in Degenerative Joint Diseases: Involvement of Proteoglycan-4 (PRG4)

Rheumatoid arthritis (RA), osteoarthritis (OA), and gout are the most prevalent degenerative joint diseases (DJDs). The pathogenesis underlying joint disease in DJDs remains unclear. Considering the severe toxicities reported with anti-inflammatory and disease-modifying agents, there is a clear need to develop new treatments that are specific in their effect while not being associated with significant toxicities. A key feature in the development of joint disease is the overexpression of adhesion molecules, e.g., CD44. Expression of CD44 and its variants in the synovial tissues of patients with DJDs is strongly associated with cartilage damage and appears to be a predicting factor of synovial inflammation in DJDs. Targeting CD44 and its downstream signaling proteins has emerged as a promising therapeutic strategy. PRG4 is a mucinous glycoprotein that binds to the CD44 receptor and is physiologically involved in joint lubrication. PRG4-CD44 is a pivotal regulator of synovial lining cell hemostasis in the joint, where lack of PRG4 expression triggers chronic inflammation and fibrosis, driven by persistent activation of synovial cells. In view of the significance of CD44 in DJD pathogenesis and the potential biological role for PRG4, this review aims to summarize the involvement of PRG4-CD44 signaling in controlling synovitis, synovial hypertrophy, and tissue fibrosis in DJDs.

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.

Protease-Activated Receptor-2 and Phospholipid Metabolism Analysis in Hyperuricemia-Induced Renal Injury

Interstitial inflammation is an important mechanism of pathological damage in renal injury caused by hyperuricemia. Protease-activated receptor-2 (PAR2) is a class of targets that act upstream of the PI3K/AKT/NF-κB pathway and is involved in various inflammatory diseases. We induced a hyperuricemia model in rats by adenine and ethambutol gavage in an in vivo experiment. We demonstrated that PAR2 and PI3K/AKT/NF-κB pathway expression were significantly upregulated in renal tissues, with massive inflammatory cell infiltration in the renal interstitium and renal tissue injury. Treating hyperuricemic rats with AZ3451, a selective metabotropic antagonist of PAR2, we demonstrated that PAR2 antagonism inhibited the PI3K/AKT/NF-κB pathway and attenuated tubular dilation and tubulointerstitial inflammatory cell infiltration. The phospholipid metabolism profiles provided a perfect separation between the normal and hyperuricemic rats. In addition, we also found that AZ3451 can affect phospholipid metabolism. Our work suggests that PAR2 may mediate hyperuricemia-mediated renal injury by activating the PI3K/AKT/NF-κB pathway. The PAR2 antagonist AZ3451 may be a promising therapeutic strategy for hyperuricemia-induced inflammatory responses.

The inflammation process of gout arthritis and its treatment

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

Gut microbiota mediated the therapeutic efficiency of Simiao decoction in the treatment of gout arthritis mice

BACKGROUND

Gut microbiota plays a significant role in the development and treatment of gouty arthritis. Simiao decoction has been shown to alleviate gouty arthritis by inhibiting inflammation, regulating NLRP3 inflammasome, and altering gut microbiota. However, there is no evidence to prove whether gut microbiota directly mediates the therapeutic efficiency of Simiao decoction in treating gout arthritis.

METHODS

In this study, fecal microbiota transplantation (FMT) was used to transfer the gut microbiota of gout arthritis mice treated with Simiao decoction or allopurinol to blank gout arthritis mice, in order to investigate whether FMT had therapeutic effects on gout arthritis.

RESULTS

Both Simiao decoction and allopurinol effectively reduced the levels of serum uric acid, liver XOD activity, foot thickness, serum IL-1β, and G-CSF in gout arthritis mice. However, Simiao decoction also had additional benefits, including raising the pain threshold, reducing serum TNF-α and IL-6, alleviating gut inflammation, and repairing intestinal pathology, which were not observed with allopurinol treatment. Moreover, Simiao decoction had a greater impact on gut microbiota than allopurinol, as it was able to restore the abundance of phylum Proteobacteria and genus Helicobacter. After transplantation into gout arthritis mice, gut microbiota altered by Simiao decoction exhibited similar therapeutic effects to those of Simiao decoction, but gut microbiota altered by allopurinol showed no therapeutic effect.

CONCLUSIONS

These findings demonstrates that Simiao decoction can alleviate gout arthritis symptoms by regulating gut microbiota.

Potential anti-gout properties of Wuwei Shexiang pills based on network pharmacology and pharmacological verification

ETHNOPHARMACOLOGICAL RELEVANCE

Wuwei Shexiang Pills (WWSX), a classic Tibetan medicine, consists of Chebulae Fructus (removed pit), Aucklandiae Radix, Moschus, Aconiti Fiavi Radix, and Acori Calami Rhizoma. It is used clinically in China to treat joint pain, swelling and other symptoms, and has the function of dispelling wind and relieving pain. However, to date, the mechanism of how it works against gout is still unclear.

AIMS OF THE STUDY

Using network pharmacology, molecular docking and pharmacological verification to explore the potential anti-gout properties of WWSX.

MATERIALS AND METHODS

With the use of UPLC-Q/TOF-MS, the main components of WWSX were obtained and screened for potential anti-inflammatory components by network pharmacology and molecular docking. The anti-inflammatory activity of the components screened from WWSX was also tested by in vitro assays. The anti-gout mechanism of WWSX was predicted by network pharmacology, and the pharmacological validation experiments using gouty arthritis model and mouse air pouch model were used to explore the multifaceted mechanism of WWSX to modify gout.

RESULT

Thirty-eight active ingredients were obtained from the UPLC-Q/TOF-MS detection. The network pharmacology and molecular docking analysis showed that 104 co-targets were participated in the treatment of gout, and the main signaling pathways involved were NOD-like receptor pathway, NF-κB pathway and MAPK pathway. Pharmacological evaluation showed that WWSX could significantly improve gout in gouty arthritis models and mouse air pouch models by modulating the above pathways.

CONCLUSION

This work has predicted and validated the anti-inflammatory material basis and predicted the anti-gout mechanism of WWSX which was verified by network pharmacology, molecular docking and in vitro cellular studies. The results reveal the mechanism of WWSX in the treatment of gout and provide a theoretical basis for its clinical application.

A review on gout: Looking back and looking ahead

Gout is a metabolic disease caused by the deposition of monosodium urate (MSU) crystals inside joints, which leads to inflammation and tissue damage. Increased concentration of serum urate is an essential step in the development of gout. Serum urate is regulated by urate transporters in the kidney and intestine, especially GLUT9 (SLC2A9), URAT1 (SLC22A12) and ABCG. Activation of NLRP3 inflammasome bodies and subsequent release of IL-1β by monosodium urate crystals induce the crescendo of acute gouty arthritis, while neutrophil extracellular traps (NETs) are considered to drive the self-resolving of gout within a few days. If untreated, acute gout may eventually develop into chronic tophaceous gout characterized by tophi, chronic gouty synovitis, and structural joint damage, leading the crushing burden of treatment. Although the research on the pathological mechanism of gout has been gradually deepened in recent years, many clinical manifestations of gout are still unable to be fully elucidated. Here, we reviewed the molecular pathological mechanism behind various clinical manifestations of gout, with a view to making contributions to further understanding and treatment.

Global burden of gout in 1990-2019: A systematic analysis of the Global Burden of Disease study 2019

BACKGROUND AND AIMS

Although gout is one of the most common rheumatic diseases, world data are lacking because most studies have focused on industrialized countries. Therefore, we aimed to investigate the global burden of gout and its associations with the year of diagnosis, age, geographical region, sociodemographic status and various further risk factors.

METHODS

Retrospective data from the Global Burden of Disease (GBD) were used, initially collected between 1990 and 2019. Raw numbers and age-standardized rates (per 100,000 persons) of prevalence, incidence and years lived with disability (YLDs) of gout were extracted from GBD 2019 for 204 countries and territories and stratified by sex, age, year, sociodemographic index and geographic region. Correlations between gout and other chronic diseases were identified, and the burden attributable to high body mass index (BMI) and kidney dysfunction was described.

RESULTS

The total number of patients and gout age-standardized prevalence rate increased between 1990 and 2019. Gout was most prevalent in Australasia and high-income North America, and a higher sociodemographic index (SDI) was associated with higher age-standardized prevalence, incidence and YLDs. High BMI and kidney dysfunction were risk factors for gout, while gout was correlated with other kidney diseases.

CONCLUSIONS

The global prevalence of gout, as well as incidence, and YLDs increased worldwide from 1990 to 2019 and had a significant association with sex, age, geographic region, SDI and risk factors. Understanding the complex interplay of environmental, sociodemographic and geographic risk factors is essential in mitigating the ever-rising disease burden of gout.

Coenzyme Q10 prevented Trypanosoma brucei rhodesiense-mediated breach of the blood brain barrier, inflammation and organ damage in late stage of Human African Trypanosomiasis

During the late stage of Human African Trypanosomiasis (HAT), there is severe cytokine-driven inflammation, oxidative stress and organ damage. Controlling inflammation and oxidative damage presents unique therapeutic opportunities to improve treatment outcome. The current study sought to determine the putative impact of Coenzyme-Q10 (Co-Q10), a potent antioxidant and anti-inflammatory, on adverse inflammatory and oxidative events during Trypanosoma brucei rhodesiense (T.b.r) infection. Group one constituted the control; the second group was infected with T.b.r; the third group was orally administered with 200 mg/kg Co-Q10 for two weeks; thereafter, Co-Q10 administration continued after infection with T.b.r. Co-Q10 improved the survival rate of infected mice and prevented full blown parasite driven splenomegaly and hepatomegaly. Co-Q10 prevented characteristic T.b.r-driven breach of the blood brain barrier and improved neurological integrity among T.b.r infected mice. Co-Q10 protected from T.b.r-induced microcytic hypochromic anaemia and thrombocytopenia. T.b.r-induced oxidative stress in the vital organs was assuaged following exposure to Co-Q10. Co-Q10 blocked T.b.r-induced derangement of high density lipoprotein and triglyceride levels. Co-Q10 significantly abrogated T.b.r-driven elevation of serum TNF-α and IFN-γ levels. Moreover, T.b.r-induced kidney and liver damage was assuaged by Co-Q10 administration. Co-Q10 administration downregulated T.b.r-induced elevation of uric acid and C-reactive protein. Likewise, T.b.r infected mice receiving Co-Q10 exhibited normal brain architecture. In conclusion, treatment with Co-Q10 may be useful in protecting against T.b.r-mediated organ injury, lethal inflammation and oxidative stress commonly present in severe late stage HAT; and presents unique opportunities for an adjunct therapy for late stage HAT.

The risk of myocardial infarction and heart failure in patients with gouty arthritis: A systematic review and meta-analysis

OBJECTIVE

By performing a meta-analysis of published cohort studies, this review aims to evaluate the association between gouty arthritis (GA) and the risk of myocardial infarction (MI) and heart failure (HF), hence providing evidence for clinical management.

METHODS

Five electronic databases were searched from inception to July 28, 2022. Relative risk (RR) and 95% confidence intervals (CI) were calculated by random-effect model or fixed-effect model to evaluate the association between GA and the risk of MI and HF, respectively.

RESULTS

Eleven articles containing 13 studies were finally selected for meta-analysis which covered 408 443 GA patients and 10 402 777 non-GA patients. The results showed that GA was associated with the risk of MI and HF (MI: RR = 1.75, 95% CI: 1.45-2.11; HF: RR = 2.00, 95% CI: 1.91-2.10). And subgroup analysis showed that female GA patients had a higher risk of MI and HF than male GA patients. Further, younger GA patients had a higher risk of MI than older patients (≤44 years: RR = 2.82, 95% CI: 1.38-5.79; 45-69: RR = 1.85, 95% CI: 1.22-2.82; ≥70: RR = 1.52, 95% CI: 1.22-1.88). GA patients were mainly associated with the occurrence of non-fatal MI (fatal MI: RR = 1.37, 95% CI: 0.76-2.48; non-fatal MI: RR = 1.75, 95% CI: 1.45-2.11).

CONCLUSIONS

GA is correlated with the risk of MI and HF. Both male and female GA patients have an increased risk of MI and HF. Meanwhile, female GA patients or younger GA patients have a higher risk of MI and HF.

The mechanism of NLRP3 inflammasome activation and its pharmacological inhibitors

NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) is a cytosolic pattern recognition receptor (PRR) that recognizes multiple pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Once activated, NLRP3 initiates the inflammasome assembly together with the adaptor ASC and the effector caspase-1, leading to caspase-1 activation and subsequent cleavage of IL-1β and IL-18. Aberrant NLRP3 inflammasome activation is linked with the pathogenesis of multiple inflammatory diseases, such as cryopyrin-associated periodic syndromes, type 2 diabetes, non-alcoholic steatohepatitis, gout, and neurodegenerative diseases. Thus, NLRP3 is an important therapeutic target, and researchers are putting a lot of effort into developing its inhibitors. The review summarizes the latest advances in the mechanism of NLRP3 inflammasome activation and its pharmacological inhibitors.

Effect of the main constituents of Pistacia lentiscus leaves against the DPPH radical and xanthine oxidase: experimental and theoretical study

The aim of this work is to study the content of phenolic compounds in P lentiscus leaves and their antioxidant effect. After extracting the phenolic compounds, fractionation by liquid/liquid partition with increasing polarity gives five extracts. Three of them (ButF, AqF and ButA) were found to have good antioxidant activity. Their IC_50s for the inhibition of the free radical formation of DPPH are 1.76 µg/mL, 1.307 µg/ml, and 1.77 µg/mL, respectively. These values are very interesting, considering the effect of the powerful flavonoid quercetin, whose IC₅₀ against DPPH is 1.53 µg/mL. These extracts are also active against xanthine oxidase (XO). The IC_50s measured are 0.14 mg/mL, 0.186 mg/mL and 0.33 mg/mL for ButF, Aq F and ButAq F extract respectively, in comparison with allopurinol (0.44 mg/mL). A phytochemical analysis by LC/ESI-MS-MS was performed to explain the observed activities. The results show 22 peaks representing: flavanols, namely catechin, d-Gallocatechin, and gallocatechin gallate. The only flavone detected in the studied extracts was luteolin glucuronide and was found to be in higher amounts in butanolic extract (2,71mg/mL). The phenolic acids and derivatives were also identified in the extracts. A theoretical study was performed to deduce the specificity of the binding between the major compounds identified in the P. lentiscus extract and the xanthine oxidase enzyme using Schrödinger software. The docking procedure was validated using the extraction of ligands from the binding site. Their re-anchoring to the xanthine oxidase structure using quercetin and allopurinol was considered reference molecules. After docking, post-docking minimization was performed to achieve the best scoring poses with the MM-GBSA approach. The dGBind energy of MM-GBSA representing the binding energy of the receptor and the ligand was calculated based on molecular mechanics. Results reveal that β-Glucogallin compounds such as Digalloylquinic acid, Gallocatechin, and Myricetin-3-O rhamnoside are more active than allopurinol, with stronger Docking score (Gscore) and MM-GBSA dGBind.Communicated by Ramaswamy H. Sarma.

Angiotensin type 2 receptor antagonism as a new target to manage gout

BACKGROUND

There is a growing search for therapeutic targets in the treatment of gout. The present study aimed to evaluate the analgesic and anti-inflammatory potential of angiotensin type 2 receptor (AT₂R) antagonism in an acute gout attack mouse model.

METHODS

Male wild-type (WT) C57BL/6 mice either with the AT₂R antagonist, PD123319 (10 pmol/joint), or with vehicle injections, or AT₂R KO mice, received intra-articular (IA) injection of monosodium urate (MSU) crystals (100 µg/joint), that induce the acute gout attack, and were tested for mechanical allodynia, thermal hyperalgesia, spontaneous nociception and ankle edema development at several times after the injections. To test an involvement of AT₂R in joint pain, mice received an IA administration of angiotensin II (0.05-5 nmol/joint) with or without PD123319, and were also evaluated for pain and edema development. Ankle joint tissue samples from mice undergoing the above treatments were assessed for myeloperoxidase activity, IL-1β release, mRNA expression analyses and nitrite/nitrate levels, 4 h after injections.

RESULTS

AT₂R antagonism has robust antinociceptive effects on mechanical allodynia (44% reduction) and spontaneous nociception (56%), as well as anti-inflammatory effects preventing edema formation (45%), reducing myeloperoxidase activity (54%) and IL-1β levels (32%). Additionally, Agtr2^tm1a mutant mice have largely reduced painful signs of gout. Angiotensin II administration causes pain and inflammation, which was prevented by AT₂R antagonism, as observed in mechanical allodynia 4 h (100%), spontaneous nociception (46%), cold nociceptive response (54%), edema formation (83%), myeloperoxidase activity (48%), and IL-1β levels (89%). PD123319 treatment also reduces NO concentrations (74%) and AT₂R mRNA levels in comparison with MSU untreated mice.

CONCLUSION

Our findings show that AT₂R activation contributes to acute pain in experimental mouse models of gout. Therefore, the antagonism of AT₂R may be a potential therapeutic option to manage gout arthritis.

Protein phosphatase 2A regulates xanthine oxidase-derived ROS production in macrophages and influx of inflammatory monocytes in a murine gout model

Background: Gout is a common arthritis, due to deposition of monosodium urate (MSU) crystals which results in IL-1β secretion by tissue-resident macrophages. Xanthine oxidase (XO) catalyzes uric acid (UA) production and in the process, reactive oxygen species (ROS) are generated which contributes to NLRP3 inflammasome activation. Protein phosphatase 2A (PP2A) may be involved in regulating inflammatory pathways in macrophages. The objective of this study was to investigate whether PP2A regulates gout inflammation, mediated by XO activity modulation. We studied UA and ROS generations in MSU stimulated murine bone marrow derived macrophages (BMDMs) in response to fingolimod phosphate, a PP2A activator, and compared its anti-inflammatory efficacy to that of an XO inhibitor, febuxostat. Methods: BMDMs were stimulated with MSU, GM-CSF/IL-1β or nigericin ± fingolimod (2.5 μM) or febuxostat (200 μM) and UA levels, ROS, XO, and PP2A activities, Xdh (XO) expression and secreted IL-1β levels were determined. PP2A activity and IL-1β in MSU stimulated BMDMs ± N-acetylcysteine (NAC) (10 μM) ± okadaic acid (a PP2A inhibitor) were also determined. M1 polarization of BMDMs in response to MSU ± fingolimod treatment was assessed by a combination of iNOS expression and multiplex cytokine assay. The in vivo efficacy of fingolimod was assessed in a murine peritoneal model of acute gout where peritoneal lavages were studied for pro-inflammatory classical monocytes (CMs), anti-inflammatory nonclassical monocytes (NCMs) and neutrophils by flow cytometry and IL-1β by ELISA. Results: Fingolimod reduced intracellular and secreted UA levels (p < 0.05), Xdh expression (p < 0.001), XO activity (p < 0.001), ROS generation (p < 0.0001) and IL-1β secretion (p < 0.0001), whereas febuxostat enhanced PP2A activity (p < 0.05). NAC treatment enhanced PP2A activity and reduced XO activity and PP2A restoration mediated NAC's efficacy as co-treatment with okadaic acid increased IL-1β secretion (p < 0.05). Nigericin activated caspase-1 and reduced PP2A activity (p < 0.001) and fingolimod reduced caspase-1 activity in BMDMs (p < 0.001). Fingolimod reduced iNOS expression (p < 0.0001) and secretion of IL-6 and TNF-α (p < 0.05). Fingolimod reduced CMs (p < 0.0001), neutrophil (p < 0.001) and IL-1β (p < 0.05) lavage levels while increasing NCMs (p < 0.001). Conclusion: Macrophage PP2A is inactivated in acute gout by ROS and a PP2A activator exhibited a broad anti-inflammatory effect in acute gout in vitro and in vivo.

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

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

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

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

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

A Selective Review and Virtual Screening Analysis of Natural Product Inhibitors of the NLRP3 Inflammasome

The NLRP3 inflammasome is currently an exciting target for drug discovery due to its role in various inflammatory diseases; however, to date, no NLRP3 inhibitors have reached the clinic. Several studies have used natural products as hit compounds to facilitate the design of novel selective NLRP3 inhibitors. Here, we review selected natural products reported in the literature as NLRP3 inhibitors, with a particular focus on those targeting gout. To complement this survey, we also report a virtual screen of the ZINC20 natural product database, predicting favored chemical features that can aid in the design of novel small molecule NLRP3 inhibitors.

The Mechanism of the NLRP3 Inflammasome Activation and Pathogenic Implication in the Pathogenesis of Gout

The NACHT, LRR, and PYD-domains-containing protein 3 (NLRP3) inflammasome is an intracellular multi-protein signaling platform that is activated by cytosolic pattern-recognition receptors such as NLRs against endogenous and exogenous pathogens. Once it is activated by a variety of danger signals, recruitment and assembly of NLRP3, ASC, and pro-caspase-1 trigger the processing and release of pro-inflammatory cytokines including interleukin-1β (IL-1β) and IL-18. Multiple intracellular and extracellular structures and molecular mechanisms are involved in NLRP3 inflammasome activation. Gout is an autoinflammatory disease induced by inflammatory response through production of NLRP3 inflammasome-mediated proinflammatory cytokines such as IL-1β by deposition of monosodium urate (MSU) crystals in the articular joints and periarticular structures. NLRP3 inflammasome is considered a main therapeutic target in MSU crystal-induced inflammation in gout. Novel therapeutic strategies have been proposed to control acute flares of gouty arthritis and prophylaxis for gout flares through modulation of the NLRP3/IL-1 axis pathway. This review discusses the basic mechanism of NLRP3 inflammasome activation and the IL-1-induced inflammatory cascade and explains the NLRP3 inflammasome-induced pathogenic role in the pathogenesis of gout.

The immunobiology of preterm labor and birth: intra-amniotic inflammation or breakdown of maternal-fetal homeostasis

In brief

The syndrome of preterm labor comprises multiple established and novel etiologies. This review summarizes the distinct immune mechanisms implicated in preterm labor and birth and highlights potential strategies for its prevention.

Abstract

Preterm birth, the leading cause of neonatal morbidity and mortality worldwide, results from preterm labor, a syndrome that includes multiple etiologies. In this review, we have summarized the immune mechanisms implicated in intra-amniotic inflammation, the best-characterized cause of preterm labor and birth, as well as novel etiologies non-associated with intra-amniotic inflammation (i.e. formally known as idiopathic). While the intra-amniotic inflammatory responses driven by microbes (infection) or alarmins (sterile) have some overlap in the participating cellular and molecular processes, the distinct natures of these two conditions necessitate the implementation of specific approaches to prevent adverse pregnancy and neonatal outcomes. Intra-amniotic infection can be treated with the correct antibiotics, whereas sterile intra-amniotic inflammation could potentially be treated by administering a combination of anti-inflammatory drugs (e.g. betamethasone, inflammasome inhibitors, etc.). Recent evidence also supports the role of fetal T-cell activation as a newly described trigger for preterm labor and birth in a subset of cases diagnosed as idiopathic. Moreover, herein we also provide evidence of two maternally-driven immune mechanisms responsible for preterm births formerly considered to be idiopathic. First, the impairment of maternal Tregs can lead to preterm birth, likely due to the loss of immunosuppressive activity resulting in unleashed effector T-cell responses. Secondly, homeostatic macrophages were shown to be essential for maintaining pregnancy and promoting fetal development, and the adoptive transfer of homeostatic M2-polarized macrophages shows great promise for preventing inflammation-induced preterm birth. Collectively, in this review, we discuss the established and novel immune mechanisms responsible for preterm birth and highlight the potential targets for novel strategies aimed at preventing the multi-etiological syndrome of preterm labor leading to preterm birth.

Anti-inflammatory and immunomodulatory activity of Mangifera indica L. reveals the modulation of COX-2/mPGES-1 axis and Th17/Treg ratio

In the context of inflammation and immunity, there are fragmented and observational studies relating to the pharmacological activity of Mangifera indica L. and its main active component, mangiferin. Therefore, we aimed to analyze the potential beneficial effects of this plant extract (MIE, 90% in mangiferin) in a mouse model of gouty arthritis, to allow the evaluation of cellular immune phenotypes and the biochemical mechanism/s beyond MIE activity. Gouty arthritis was induced by the intra-articular administration of MSU crystals (200μg 20μl^-1), whereas MIE (0.1-10mgkg^-1) or corresponding vehicle (DMSO/saline 1:3) were orally administrated concomitantly with MSU (time 0), 6 and 12h after the stimulus. Thereafter, knee joint score and oedema were evaluated in addition to western blot analysis for COX-2/mPGES-1 axis. Moreover, the analysis of pro/anti-inflammatory cyto-chemokines coupled with the phenotyping of the cellular infiltrate was performed. Treatment with MIE revealed a dose-dependent reduction in joint inflammatory scores with maximal inhibition observed at 10mgkg^-1. MIE significantly reduced leukocyte infiltration and activation and the expression of different pro-inflammatory cyto-chemokines in inflamed tissues. Furthermore, biochemical analysis revealed that MIE modulated COX-2/mPGES-1 and mPGDS-1/PPARγ pathways. Flow cytometry analysis also highlighted a prominent modulation of inflammatory monocytes (CD11b⁺/CD115⁺/LY6C^hi), and Treg cells (CD4⁺/CD25⁺/FOXP3⁺) after MIE treatment. Collectively, the results of this study demonstrate a novel function of MIE to positively affect the local and systemic inflammatory/immunological perturbance in the onset and progression of gouty arthritis.

Carvacrol Alleviates Hyperuricemia-Induced Oxidative Stress and Inflammation by Modulating the NLRP3/NF-κB Pathwayt

Purpose

Gouty arthritis is generally induced by the accumulation of monosodium urate (MSU) crystals in the joints due to elevated serum uric acid levels, potentially leading to serious pathological disorders such as nephrolithiasis, renal failure, and acute gouty arthritis. In this study, we aimed to validate the anti-gout effects of carvacrol, a phenolic monoterpene.

Materials and Methods

Male Sprague–Dawley rats were divided into normal saline, disease group by injecting potassium mono-oxonate (PO) at a dose of 250 mg/kg, and three treatment groups, either with carvacrol 20 mg/kg or 50 mg/kg and 10 mg/kg allopurinol. The blood and tissue samples were subsequently collected and analyzed using different biochemical and histopathological techniques.

Results

Our results revealed a significant increase in the serum levels of oxidative stress-related markers, namely, uric acid and C-reactive protein (CRP), and NLRP3 inflammasome-dependent inflammatory mediators, including nuclear factor kappa B (NF-κB) and tumor necrosis factor-alpha (TNF-α). Carvacrol administration for seven consecutive days exhibited significant anti-hyperuricemic and anti-inflammatory effects in a dose-dependent manner. Notably, the 50 mg/kg carvacrol treatment was observed to produce results similar to the allopurinol treatment. Furthermore, the renal safety of carvacrol was confirmed by the renal function test.

Conclusion

Carvacrol potentially alleviates hyperuricemia-induced oxidative stress and inflammation by regulating the ROS/NRLP3/NF-κB pathway, thereby exerting protective effects against joint degeneration.

Identification of novel protein kinase C-βII inhibitors: virtual screening, molecular docking and molecular dynamics simulation studies

Diabetic wounds (DWs) are the major end-stage manifestation encountered in diabetic patients. The two major pathways involved in the pathogenesis of DW are impaired angiogenesis and unnecessary NETosis, which are regulated by a common enzyme called protein kinase C (PKC)-βII. PKC-βII is a conventional isoform of PKC family that can be activated by calcium and diacylglycerol. PKC-βII possesses a specific expression profile and plays a distinct role in various cellular and molecular functions. The pathogenic role of PKC-βII and its involvement in the impairment of wound healing suggested that PKC-βII plays a potential role in DW progression. Hence, there is a renewed interest in developing specific inhibitors of PKC-βII. In the present study, receptor-based virtual screening was performed for the identification of potential PKC-βII inhibitors using TimTec, Enamine, Zinc and Specs databases. A total of 595 candidate compounds were evaluated based on absorption, distribution, metabolism, excretion and toxicity, standard precision docking. Further, extra-precision docking and binding free energy calculations were carried out for top-ranked compounds. Based on Glide score and protein-ligand interactions, we have identified compound 1 as a potential inhibitor. Finally, molecular dynamics (MD) simulation was performed for top compound 1 using the Desmond module (Schrödinger suite) to identify the structural stability of the protein-ligand complex. Gratifyingly, MD trajectory analysis demonstrated the stable binding conformation of compound 1 with PKC-βII enzyme. In silico approaches incorporated in this study provide a set of new putative PKC-βII inhibitors which could be potential leads to develop DW therapeutics.

Monosodium urate crystals regulate a unique JNK-dependent macrophage metabolic and inflammatory response

Monosodium urate crystals (MSUc) induce inflammation in vivo without prior priming, raising the possibility of an initial cell-autonomous phase. Here, using genome-wide transcriptomic analysis and biochemical assays, we demonstrate that MSUc alone induce a metabolic-inflammatory transcriptional program in non-primed human and murine macrophages that is markedly distinct to that induced by LPS. Genes uniquely upregulated in response to MSUc belong to lipid and amino acid metabolism, glycolysis, and SLC transporters. This upregulation leads to a metabolic rewiring in sera from individuals and mice with acute gouty arthritis. Mechanistically, the initiating inflammatory-metabolic changes in acute gout flares are regulated through a persistent expression and increased binding of JUN to the promoter of target genes through JNK signaling-but not P38-in a process that is different than after LPS stimulation and independent of inflammasome activation. Finally, pharmacological JNK inhibition limits MSUc-induced inflammation in animal models of acute gouty inflammation.

Recombinant Human Proteoglycan 4 Regulates Phagocytic Activation of Monocytes and Reduces IL-1β Secretion by Urate Crystal Stimulated Gout PBMCs

Objectives

To compare phagocytic activities of monocytes in peripheral blood mononuclear cells (PBMCs) from acute gout patients and normal subjects, examine monosodium urate monohydrate (MSU) crystal-induced IL-1β secretion ± recombinant human proteoglycan 4 (rhPRG4) or interleukin-1 receptor antagonist (IL-1RA), and study the anti-inflammatory mechanism of rhPRG4 in MSU stimulated monocytes.

Methods

Acute gout PBMCs were collected from patients in the Emergency Department and normal PBMCs were obtained from a commercial source. Monocytes in PBMCs were identified by flow cytometry. PBMCs were primed with Pam3CSK4 (1μg/mL) for 24h and phagocytic activation of monocytes was determined using fluorescently labeled latex beads. MSU (200μg/mL) stimulated IL-1β secretion was determined by ELISA. Reactive oxygen species (ROS) generation in monocytes was determined fluorometrically. PBMCs were incubated with IL-1RA (250ng/mL) or rhPRG4 (200μg/mL) and bead phagocytosis by monocytes was determined. THP-1 monocytes were treated with MSU crystals ± rhPRG4 and cellular levels of NLRP3 protein, pro-IL-1β, secreted IL-1β, and activities of caspase-1 and protein phosphatase-2A (PP2A) were quantified. The peritoneal influx of inflammatory and anti-inflammatory monocytes and neutrophils in Prg4 deficient mice was studied and the impact of rhPRG4 on immune cell trafficking was assessed.

Results

Enhanced phagocytic activation of gout monocytes under basal conditions (p<0.001) was associated with ROS generation and MSU stimulated IL-1β secretion (p<0.05). rhPRG4 reduced bead phagocytosis by normal and gout monocytes compared to IL-1RA and both treatments were efficacious in reducing IL-1β secretion (p<0.05). rhPRG4 reduced pro-IL-1β content, caspase-1 activity, conversion of pro-IL-1β to mature IL-1β and restored PP2A activity in monocytes (p<0.05). PP2A inhibition reversed rhPRG4’s effects on pro-IL-1β and mature IL-1β in MSU stimulated monocytes. Neutrophils accumulated in peritoneal cavities of Prg4 deficient mice (p<0.01) and rhPRG4 treatment reduced neutrophil accumulation and enhanced anti-inflammatory monocyte influx (p<0.05).

Conclusions

MSU phagocytosis was higher in gout monocytes resulting in higher ROS and IL-1β secretion. rhPRG4 reduced monocyte phagocytic activation to a greater extent than IL-1RA and reduced IL-1β secretion. The anti-inflammatory activity of rhPRG4 in monocytes is partially mediated by PP2A, and in vivo, PRG4 plays a role in regulating the trafficking of immune cells into the site of a gout flare.

Coffea arabica extracts and their chemical constituents in a murine model of gouty arthritis: How they modulate pain and inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Coffea arabica is commonly known for its cardiotonic and neurotonic activities, but in some places' folk medicine, like in Arabia and Africa, C. arabica is used to treat headache, migraine, the flu, anemia, oedema, asthenia, asthma, inflammation and wounds.

AIMS OF THE STUDY

The aims were to evaluate if the aqueous extracts of Coffea arabica, prepared from beans with different degrees of roasting, and their main chemical constituents could exert an in vivo anti-gouty effect.

MATERIALS AND METHODS

Coffea extracts were obtained from the beans of not roasted, light, medium and dark roasted coffee and from decaffeinated and traditional coffees and were prepared with water at 25°C and at 98°C. C57BL/6 mice were induced to gout by an injection of monosodium urate crystals and treated with coffee extracts at doses of 25, 75 and 225 mg/kg and their chemical constituents at a dose of 10 mg/kg. The antinociceptive and anti-inflammatory effects were evaluated.

RESULTS

Treatments with Coffea extracts prepared with water at 98°C were more effective to exert antinociceptive and anti-inflammatory activities than the ones prepared with water at 25°C. Caffeic and chlorogenic acids reduced hypernociception in animals when compared with negative control group (7.79 and 5.69 vs 18.53; P < 0.05 and P < 0.001, respectively), inhibited neutrophil migration (1.59 × 104 and 0.38 × 104 vs 9.47 × 104; P < 0.0001 both) and decreased pro-inflammatory cytokines concentration (IL-1β, IL-6 and TNF-α).

CONCLUSIONS

We have demonstrated that our treatments attenuated gout, and this effect could be attributed to a reducement in hypernociception, neutrophil migration and cytokines concentration. These results suggest coffee as a potential candidate for studies in acute gout therapy.

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

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

Evaluation of Antioxidant Activity and Histopathological Changes Occurred by the Oral Ingestion of CuO Nanoparticles in Monosodium Urate Crystal-Induced Hyperuricemic BALB/c Mice

Nanotechnology is an intensive branch of science due to the unique features of nano range particles (1-100 nm). Their nano size results in a high surface area of absorption when orally administered. Monosodium urate crystal excessive deposition causes a commonly known inflammatory disease called gout into the synovial joints. Previously it has been observed that copper oxide nanoparticles (CuONPs) had a significant effect in reducing the serum uric acid levels in BALB/c mice as well as reducing the inflammation in the ankles of mice. This study was made to investigate the antioxidant and histopathological changes in hyperuricemic BALB/c mice upon the oral administration of copper oxide nanoparticles. Different concentrations of copper oxide nanoparticles 5, 10, and 20 ppm were given orally to gouty mice. To investigate the antioxidant activity of CuONPs, various antioxidant protocols were applied. It was noted that the nanoparticle-treated group of 20 ppm showed no significant changes in superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), thiobarbituric acid reactive substances (TBARS), and ROS values while the protein estimation values of the negative control group exhibited a significant increase (0.001). When compared to negative control, no significant effect was shown on the interpretation of histopathological changes of muscles, kidney, and liver tissues.

An Update on the Pathogenic Role of Neutrophils in Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still's Disease

Neutrophils are innate immune phagocytes that play a key role in immune defense against invading pathogens. The main offensive mechanisms of neutrophils are the phagocytosis of pathogens, release of granules, and production of cytokines. The formation of neutrophil extracellular traps (NETs) has been described as a novel defense mechanism in the literature. NETs are a network of fibers assembled from chromatin deoxyribonucleic acid, histones, and neutrophil granule proteins that have the ability to kill pathogens, while they can also cause toxic effects in hosts. Activated neutrophils with NET formation stimulate autoimmune responses related to a wide range of inflammatory autoimmune diseases by exposing autoantigens in susceptible individuals. The association between increased NET formation and autoimmunity was first reported in antineutrophil cytoplasmic antibody-related vasculitis, and the role of NETs in various diseases, including systemic lupus erythematosus, rheumatoid arthritis, and psoriasis, has since been elucidated in research. Herein, we discuss the mechanistic role of neutrophils, including NETs, in the pathogenesis of systemic juvenile idiopathic arthritis (SJIA) and adult-onset Still’s disease (AOSD), and provide their clinical values as biomarkers for monitoring and prognosis.

Galectin-9 Regulates Monosodium Urate Crystal-Induced Gouty Inflammation Through the Modulation of Treg/Th17 Ratio

Gout is caused by depositing monosodium urate (MSU) crystals within the articular area. The infiltration of neutrophils and monocytes drives the initial inflammatory response followed by lymphocytes. Interestingly, emerging evidence supports the view that in situ imbalance of T helper 17 cells (Th17)/regulatory T cells (Treg) impacts the subsequent damage to target tissues. Galectin-9 (Gal-9) is a modulator of innate and adaptive immunity with both pro- and anti-inflammatory functions, dependent upon its expression and cellular location. However, the specific cellular and molecular mechanisms by which Gal-9 modulates the inflammatory response in the onset and progression of gouty arthritis has yet to be elucidated. In this study, we sought to comprehensively characterise the functional role of exogenous Gal-9 in an in vivo model of MSU crystal-induced gouty inflammation by monitoring in situ neutrophils, monocytes and Th17/Treg recruited phenotypes and related cyto-chemokines profile. Treatment with Gal-9 revealed a dose-dependent reduction in joint inflammation scores, knee joint oedema and expression of different pro-inflammatory cyto-chemokines. Furthermore, flow cytometry analysis highlighted a significant modulation of infiltrating inflammatory monocytes (CD11b⁺/CD115⁺/LY6-C^hi) and Th17 (CD4⁺/IL-17⁺)/Treg (CD4⁺/CD25⁺/FOXP-3⁺) cells following Gal-9 treatment. Collectively the results presented in this study indicate that the administration of Gal-9 could provide a new therapeutic strategy for preventing tissue damage in gouty arthritic inflammation and, possibly, in other inflammatory-based diseases.

Inhibitory effects of sulforaphane on NLRP3 inflammasome activation

SFN, a dietary phytochemical, is a significant member of isothiocyanates present in cruciferous vegetables at high levels in broccoli. It is a well-known activator of the Nrf2/ARE antioxidant pathway. Long since, the therapeutic effects of SFN have been widely studied in several different diseases. Other than the antioxidant effect, SFN also exhibits an anti-inflammatory effect through suppression of various mechanisms, including inflammasome activation. Considerably, SFN has been demonstrated to inhibit multiple inflammasomes, including NLRP3 inflammasome. NLRP3 inflammasome induces secretion of pro-inflammatory cytokines and promotes inflammatory cell death. The release of pro-inflammatory cytokines enhances the inflammatory response, in turn leading to tissue damage. These self-propelling inflammatory responses would need modulation with exogenous therapeutic agents to suppress them. SFN is a promising candidate molecule for the mitigation of NLRP3 inflammasome activation, which has been related to the pathogenesis of numerous disorders. In this review, we have provided fundamental knowledge about Sulforaphane, elaborated its characteristics, and evidentially focused on its mechanisms of action with regard to its anti-inflammatory, anti-oxidative, and neuroprotective features. Thereafter, we have summarized both in vitro and in vivo studies regarding SFN effect on NLRP3 inflammasome activation.

Management of gout in chronic kidney disease: a G-CAN Consensus Statement on the research priorities

Gout and chronic kidney disease (CKD) frequently coexist, but quality evidence to guide gout management in people with CKD is lacking. Use of urate-lowering therapy (ULT) in the context of advanced CKD varies greatly, and professional bodies have issued conflicting recommendations regarding the treatment of gout in people with concomitant CKD. As a result, confusion exists among medical professionals about the appropriate management of people with gout and CKD. This Consensus Statement from the Gout, Hyperuricemia and Crystal-Associated Disease Network (G-CAN) discusses the evidence and/or lack thereof for the management of gout in people with CKD and identifies key areas for research to address the challenges faced in the management of gout and CKD. These discussions, which address areas for research both in general as well as related to specific medications used to treat gout flares or as ULT, are supported by separately published G-CAN systematic literature reviews. This Consensus Statement is not intended as a guideline for the management of gout in CKD; rather, it analyses the available literature on the safety and efficacy of drugs used in gout management to identify important gaps in knowledge and associated areas for research.

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

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

Network pharmacology and molecular docking analysis on molecular targets: Mechanisms of baicalin and baicalein against hyperuricemic nephropathy

Oxidative stress and inflammation in kidney are the main causes for hyperuricemic nephropathy (HN). Baicalin and baicalein, two flavonoids, have anti-inflammatory and anti-oxidative effects and they are interconvertible in the body. In this study, both baicalin and baicalein were administered by intragastric administration (i.g.) or intraperitoneal injection (i.p.) at the dose of 50 mg kg^-1, once a day for 15 consecutive days to HN mice, a model established by i.g. of yeast extract combined with i.p. of potassium oxonate. In HN mice, baicalin and baicalein reduced serum uric acid (SUA) levels and protected kidneys by anti-inflammatory and anti-oxidative effects. Mechanistically, the effect of baicalin and baicalein on reducing SUA levels might due to their inhibitory effect on xanthine oxidase (XO) activity in vivo and in vitro. Furthermore, the mechanisms of baicalin and baicalein against HN were analyzed with network pharmacology and molecular docking technology. The network pharmacology indicated that the protective effects of baicalin and baicalein against HN were mainly related to their down-regulating effects on TLRs, NF-κB, MAPK, PI3K/AKT and NOD-like receptor signaling pathways. Molecular docking indicated high binding affinity of baicalin/baicalein to targets such as AKT1 and MAPK1. In summary, baicalin and baicalein are promising drug candidates for the treatment of HN by inhibiting XO activity, reducing inflammation and cell apoptosis through down-regulating TLRs/NLRP3/NF-κB, MAPK, PI3K/AKT/NF-κB pathways.

Autoinflammatory Features in Gouty Arthritis

In the panorama of inflammatory arthritis, gout is the most common and studied disease. It is known that hyperuricemia and monosodium urate (MSU) crystal-induced inflammation provoke crystal deposits in joints. However, since hyperuricemia alone is not sufficient to develop gout, molecular-genetic contributions are necessary to better clinically frame the disease. Herein, we review the autoinflammatory features of gout, from clinical challenges and differential diagnosis, to the autoinflammatory mechanisms, providing also emerging therapeutic options available for targeting the main inflammatory pathways involved in gout pathogenesis. This has important implication as treating the autoinflammatory aspects and not only the dysmetabolic side of gout may provide an effective and safer alternative for patients even in the prevention of possible gouty attacks.

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

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

Association of serum uric acid with clinical and radiological severity of knee osteoarthritis in non-gouty patients

Background

A growing body of evidence suggested that uric acid (UA) may contribute in the pathways underlying osteoarthritis (OA) pathogenesis; however, studies that investigated the relationship between UA and OA emerged inconclusive results. The purpose of the study was to explore the association of serum uric acid (sUA) levels with clinical severity, radiological severity of knee osteoarthritis (KOA) based on Kellgren-Lawrence (KL) grading system, and MRI changes in non-gouty patients.

Results

WOMAC scores: pain, stiffness, function, and total score are significantly higher in H-sUA group than L-sUA group (p = 0.004, p = 0.019, p = 0.018, p = 0.008 respectively). Joint space width (JSW) is significantly narrower in H-sUA group than L-sUA group (p = 0.013). H-sUA group had more frequent KL grade 4 (p < 0.001), osteophytes grade 4 (p < 0.001), focal bone erosion (p < 0.001), bone marrow lesions (p = 0.023), and synovitis (p = 0.011) than L-sUA group. Female KOA patients in H-sUA group had significantly higher pain, stiffness, and function and total WOMAC scores than L-sUA group (p = 0.003, p = 0.015, p = 0.008, p = 0.004), more frequently had KL grade 4 and osteophytes grade 4 (p = 0.003, p < 0.001), significantly narrower JSW (p = 0.016), more frequently show focal bone erosion (p = 0.002), bone marrow lesions (p = 0.019), and synovitis (p = 0.004) than L-sUA group. In regression analysis, female sex (p = 0.035), duration of KOA (p = 0.031), and sUA level (p = 0.025) were associated with KL severity. For female patients with KOA, KL severity is associated with duration of KOA (p = 0.045) and sUA (p = 0.009).

Conclusion

Higher sUA level is associated with higher clinical severity, higher radiographic KL grades, and more frequent MRI findings in patients with primary KOA patients. Our results also indicated that sUA level was significantly associated with KOA severity in female patients, but not in male patients. More studies are warranted to explore whether the two conditions exist simultaneously or there is a direct causal relationship between the two conditions.

Anti-NLRP3 Inflammasome Natural Compounds: An Update

The nucleotide-binding domain and leucine-rich repeat related (NLR) family, pyrin domain containing 3 (NLRP3) inflammasome is a multimeric protein complex that recognizes various danger or stress signals from pathogens, the host, and the environment, leading to activation of caspase-1 and inducing inflammatory responses. This pro-inflammatory protein complex plays critical roles in pathogenesis of a wide range of diseases including neurodegenerative diseases, autoinflammatory diseases, and metabolic disorders. Therefore, intensive efforts have been devoted to understanding its activation mechanisms and to searching for its specific inhibitors. Approximately forty natural compounds with anti-NLRP3 inflammasome properties have been identified. Here, we provide an update about new natural compounds that have been identified within the last three years to inhibit the NLRP3 inflammasome and offer an overview of the underlying molecular mechanisms of their anti-NLRP3 inflammasome activities.

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

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