Inflammation in gout: mechanisms and therapeutic targets

Anti-inflammatory effect of Plantago asiatica crude extract in rat gout arthritis model

Plantago asiatica L., a perennial herb in the family Plantaginaceae, has been shown to impart several pharmacologic activities, including anti-oxidative, anti-inflammatory, and diuretic effects. In the study here, the anti-gout(y) arthritis (GA) effects of a crude extract from P. asiatica L. (PAE) were investigated in a rat GA model. For this, PAE was prepared by ethanol extraction and analyzed for phytochemicals by RP-HPLC and Q-TOF-MS. Thereafter, potential therapeutic effects of the PAE were investigated in rats; Wistar rats (male, 8 wk-of-age) were randomly allocated into four groups (n = 9/group) and intra-articularly injected with 3 mg monosodium urate (MSU) in saline solution to establish a GA model. For the study, rats received oral dosings of 0.3 mg colchicine/kg or 1 g PAE/kg (w/w) before and after gout was established. At fixed times after the treatments, assessment of joint swelling ratios and pathological changes in the joints, as well as of select cytokine expression in the blood, was done. RP-HPLC results showed the PAE contained at least 8 'active' ingredients, with plantamajoside, verbascoside, and cymaroside being the most abundant. In comparison to in control rats, MSU induced joint space narrowing, ankle joint swelling, and increased levels of pro-inflammatory interleukin (IL)-1β, IL-17a, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, and reductions in anti-inflammatory IL-10 in the blood. PAE treatment significantly reversed patho- genic joint space narrowing and swelling, reversed the MSU-induced changes in inflammatory factors, and in general imparted effects very similar to those seen with colchicine (COL; known non-steroidal anti-inflammatory drug for clinical treatment of GA). Collectively, these findings provide experimental evidence supporting the potential applicability of PAE to treat gouty arthritis.

Disruption of survivin protein expression by treatment with YM155 accelerates the resolution of neutrophilic inflammation

BACKGROUND AND PURPOSE

Prolonged survival of neutrophils is essential for determining the progression and severity of inflammatory and immune-mediated disorders, including gouty arthritis. Survivin, an anti-apoptotic molecule, has been described as a regulator of cell survival. This study aims to examine the effects of YM155 treatment, a survivin selective suppressant, in maintaining neutrophil survival in vitro and in vivo experimental settings of neutrophilic inflammation.

EXPERIMENTAL APPROACH

BALB/c mice were injected with monosodium urate (MSU) crystals and treated with YM155 (intra-articularly) at the peak of inflammatory response. Leukocyte recruitment, apoptosis neutrophil and efferocytosis were determined by knee joint wash cell morphology counting and flow cytometry. Resolution interval (Ri) was quantified by neutrophil infiltration, monitoring the amplitude and duration of the inflammation. Cytokine production was measured by ELISA. Mechanical hypernociception was assessed using an electronic von Frey aesthesiometer. Efferocytosis was evaluated in zymosan-induced neutrophilic peritonitis. Survivin and cleaved caspase-3 expression was determined in human neutrophils by flow cytometry.

KEY RESULTS

Survivin was expressed in neutrophils during MSU-induced gout, and the treatment with YM155 reduced survivin expression and shortened Ri from ∼8 h observed in vehicle-treated mice to ∼5.5 h, effect accompanied by increased neutrophil apoptosis and efferocytosis, both crucial for the inflammation resolution. Reduced IL-1β and CXCL1 levels were also observed in periarticular tissue. YM155 reduced histopathological score and hypernociceptive response. In human neutrophils, lipopolysaccharide (LPS) increased survivin expression, whereas survivin inhibition with YM155 induced neutrophil apoptosis, with activation of caspase-3.

CONCLUSIONS AND IMPLICATIONS

Survivin may be a promising therapeutic target to control neutrophilic inflammation.

Genetically Predicted Plasma Metabolome Mediates the Causal Link Between Immune Cells and Risk of Gout

BACKGROUND

Gout is a prevalent metabolic disorder characterized by a multifaceted process of development. Recent research has emphasized a robust correlation between the immune response and gout. Nevertheless, it is still uncertain if this connection is causative. Hence, the objective of this study was to investigate the causal relationship between immune cells and gout, while also analyzing the role of the plasma metabolome as metabolic mediators in this biological process.

METHODS

This study explored the causal link between different subtypes of immune cells and gout using two-sample Mendelian randomization (MR). To confirm the reliability of the findings, reverse MR analysis, steiger test and sensitivity tests were conducted. A two-step mediation analysis was used to gain insight into the role of plasma metabolites as intermediate mediators.

RESULTS

This two-sample, bidirectional, two-step MR analysis found a nominal causal link between 33 immune cells as well as 47 known plasma metabolites and gout. Reverse MR analysis and sensitivity tests demonstrated the reliability of the MR results. In addition, we found that Tetradecadienedioate (C14:2-DC) played a partially mediating role in the CD4 on activated CD4 regulatory T cell and gout pathways, with a mediating proportion of 13.16%, (95% CI = 0.65%-25.67%, p = 0.034).

CONCLUSION

The objective of our research was to investigate the possible causative connection between immune cells and gout. Our findings indicate that certain plasma metabolites may play a role in mediating this association. This study offers novel insights and sources of information that may contribute to the early detection and proactive measures to avoid gout in the future.

Genetic causality between insomnia and specific orthopedic conditions: Insights from a two-sample Mendelian randomization study

OBJECTIVE

To investigate the genetic causality for the insomnia and common orthopedic diseases, such as rheumatoid arthritis (RA), ankylosing spondylitis (AS), osteoporosis (OP), and gout (GT).

METHODS

The genome-wide association study (GWAS) summary data on insomnia were obtained from a published study, while the GWAS summary data on RA, AS, OP, and GT were sourced from the FinnGen consortium. We utilized the TwoSampleMR package of the R software (version 4.1.2) to conduct a two-sample Mendelian randomization (MR) analysis. Our primary method of analysis was the random-effects inverse variance weighted (IVW) approach. Subsequently, we conducted a series of sensitivity analyses for the MR analysis.

RESULTS

The MR analysis revealed a positive genetic causal relationship between insomnia and RA (P = 0.016, odds ratio [OR] 95 % confidence interval [CI] = 1.112 [1.020-1.212]). However, no significant genetic causal relationship was observed between insomnia and AS (P = 0.194, OR 95 % CI = 1.121 [0.944-1.331]), OP (P = 0.788, OR 95 % CI = 1.016 [0.904-1.142]), and GT (P = 0.757, OR 95 % CI = 1.018 [0.912-1.136]). The MR analysis did not exhibit heterogeneity, horizontal pleiotropy, outlier effects, or dependence on a single SNP, and demonstrated normal distribution, which guaranteed the robustness of the results.

CONCLUSION

The results of this study suggest that insomnia may be a significant risk factor for RA, and controlling insomnia may represent a promising strategy for preventing RA. While insomnia was not observed to be associated with AS, OP, and GT at the genetic level, other levels of association cannot be excluded.

Palmatine, an isoquinoline alkaloid from Phellodendron amurense Rupr., ameliorated gouty inflammation by inhibiting pyroptosis via NLRP3 inflammasome

ETHNOPHARMACOLOGICAL RELEVANCE

Palmatine (Pal), derived from Daemonorops margaritae (Hance) Becc and Phellodendron amurense Rupr. is a natural isoquinoline alkaloid widely used in clearing heat and drying dampness, purging the pathogenic fire and removing symptoms, detoxifying toxins and healing sores.

AIM OF THE STUDY

Gout is a common metabolic inflammatory disease caused by the deposition of MSU crystals (MSU) in joints and non-articulation structures. Given the multiple toxic side effects of clinical anti-gout medications, there is a need to find a safe and effective alternative. We investigated the therapeutic effects of Pal on MSU crystal-induced acute gouty inflammation, targeting the NLRP3 inflammasome mediated pyroptosis.

MATERIALS AND METHODS

In vitro, mouse peritoneal macrophages (MPM) and rat articular chondrocytes were stimulated with LPS plus MSU in the presence or absence of Palmatine. In vivo, arthritis models include the acute gouty arthritis model by injecting MSU crystals in the paws of mice and the air pouch acute gout model by injecting MSU crystals into the mouse subcutaneous tissue of the back. Expression of NLRP3 inflammasome activation and NETosis formation was determined by Western blot, ELISA kit, immunohistochemistry, and immunofluorescence. In addition, the anti-cartilage damage of Palmatine on MSU-induced arthritis mice were also evaluated.

RESULTS

Pal dose-dependently decreased levels of NLRP3 inflammasome activation related proteins NLRP3, ASC, caspase-1, IL-1β, HMGB1 and Cathepsin B. The NETosis protein levels of caspase-11, histone3, PR3 and PAD4 were remarkably reduced by Pal. Pal effectively blocked the activation of NLRP3 inflammasome, attenuated the caspase-11 mediated noncanonical NLRP3 inflammasome activation and intervened the formation of NETs, thereby inhibiting the pyroptosis. In vivo, Pal attenuated MSU-induced inflammation in gouty arthritis and protect the articular cartilage through inhibiting the pyroptosis of proteins NLRP3, ASC, caspase-1, IL-1β, HMGB1 and Cathepsin B, reducing levels of NETosis relevant proteins caspase-11, histone3, PR3 and PAD4 and up-regulating expression of protein MMP-3.

CONCLUSION

Palmatine ameliorated gouty inflammation by inhibiting pyroptosis via NLRP3 inflammasome.

Mechanism of Biqi capsules in the treatment of gout based on network pharmacology and experimental verification

ETHNOPHARMACOLOGICAL RELEVANCE

Gout is a crystal-related arthropathy caused by monosodium urate (MSU) deposition, resulting from purine metabolism disorders and hyperuricemia (HUA). Gout belongs to the traditional medicine category of Bi syndrome. Biqi capsules (BQ) is a traditional Chinese medicine formula used to treat Bi syndrome. The BQ prescription is derived from the ancient prescription of Hua Tuo, a famous physician in the Han Dynasty.

AIM OF THE STUDY

To study the effect and mechanism of BQ in treating acute gouty arthritis (AGA) and HUA.

MATERIALS AND METHODS

Analyzing BQ's signaling pathways for gout treatment via network pharmacology. The HUA model was induced orally with adenine and potassium oxonate. The rat AGA model was established by MSU injection. In vitro, MH7A and RAW 246.7 cells were treated with LPS and MSU. Serum uric acid, creatinine, and urea nitrogen levels were evaluated. Kidney and ankle joint pathology was observed via HE staining. Inflammatory signaling pathway proteins, epithelial-mesenchymal transition (EMT) pathway proteins, and uric acid metabolism-related proteins were detected by Western blot.

RESULTS

1780 potential targets for gout treatment were identified, and 1039 target proteins corresponding to BQ's active ingredients were obtained. Pathway enrichment analysis revealed BQ improved gout mainly through inflammatory pathways. Experimental results showed BQ could reduce serum uric acid level and increase uric acid clearance rate by regulating the expression of adenosine deaminase (ADA), and organic anion transporter 1 (OAT1) and glucose transporter 9 (GLUT9) in HUA mice. BQ could improve renal function and injury by inhibiting the NLRP3 pathway in HUA mice' kidneys. Additionally, BQ could alleviate ankle joint swelling and synovial injury, inhibit the TLR4/NLRP3 pathway, and reduce levels of inflammatory factors including interleukin 6 (IL-6), interleukin 1β (IL-1β), and tumor necrosis factor-alpha (TNF-α) in AGA rats. The main component of BQ, brucine, could inhibit the activation of NLRP3/NF-κB pathway induced by MSU and reduce the expression level of inflammatory factors (IL-6, IL-1β, and TNF-α) in macrophages. Brucine could inhibit the activation of the EMT pathway and reduce the expression level of inflammatory factors (IL-6, TNF-α) in human fibroblast-like synoviocytes (MH7A cells) induced by MSU.

CONCLUSIONS

BQ effectively reduced serum uric acid levels, improved kidney and joint damage, and ameliorated the inflammatory response caused by MSU. Its main component, brucine, effectively improved the inflammatory response and reduced the invasive ability of synoviocytes induced by MSU.

Limosilactobacillus reuteri RE225 alleviates gout by modulating the TLR4/MyD88/NF-κB inflammatory pathway and the Nrf2/HO-1 oxidative stress pathway, and by regulating gut microbiota

BACKGROUND

Gout poses a significant health threat. The use of Lactobacillus from the gut microbiota is one potential remedy. However, the intricate molecular mechanisms governing the impact of Lactobacillus on gout remain largely uncharted. In this study, a strain of Limosilactobacillus reuteri RE225 was separated from the gut of mice and colitis was treated with polypeptide intervention.

RESULTS

Limosilactobacillus reuteri RE225 reduced foot tumefaction markedly in mice with gout and extended the pain threshold time in their feet. It also improved the health of gut microbiota. Intervention with L. reuteri RE225 also suppressed the TLR4/MyD88/NF-κB and nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathways in the mice, reduced the levels of pro-inflammatory cytokines - interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α) - and increased the level of the anti-inflammatory cytokine interleukin 10 (IL-10), thereby mitigating inflammation.

CONCLUSION

This study provides a theoretical basis for the comprehensive development of Limosilactobacillus reuteri and new ideas for the non-pharmacological treatment of gout. © 2024 Society of Chemical Industry.

Plug-In Design of the Microneedle Electrode Array for Multi-Parameter Biochemical Sensing in Gouty Arthritis

Gouty arthritis is one of the most common forms of inflammatory arthritis and has brought a significant burden on patients and society. Current strategies for managing gout primarily focus on long-term urate-lowering therapy. With the rapid advancement of point-of-care testing (POCT) technology, continuous monitoring of gout-related biomarkers like uric acid (UA) or inflammatory cytokines can provide rapid and personalized diagnosis for gout management. In this study, a plug-in design of a microneedle electrode array (PIMNA) was developed and integrated into a multi-parameter sensing portable system in combination with embedded circuits and a mobile application. The system enabled real-time, in situ, and dynamic monitoring of biomarkers, including UA, reactive oxygen species (ROS), and pH at gouty joints. The multi-parameter monitoring system demonstrated a wide linear response range, excellent selectivity, stability, reproducibility, and reliable signal transmission performance. In vivo experiments demonstrated the real-time monitoring capability of PIMNA for UA, ROS, and pH, showing the potential to facilitate urate-lowering management and inflammation assessment. Prospectively, the system enables quantitative analysis of the complexity and diversity of gout, presenting promising applications in clinical practice. This work provides a unique strategy with potential for broader applications in gout management and arthritic disease treatment.

Therapeutic potential and pharmacological mechanisms of Traditional Chinese Medicine in gout treatment

Gout is a systemic metabolic disorder caused by elevated uric acid (UA) levels, affecting over 1% of the population. The most common complication of gout is gouty arthritis (GA), characterized by swelling, pain or tenderness in peripheral joints or bursae, which can lead to the formation of tophi. At present, western medicines like colchicine, febuxostat and allopurinol are the primary treatment strategy to alleviate pain and prevent flare-ups in patients with GA, but they have significant side effects and increased mortality risks. Traditional Chinese medicine (TCM) has been utilized for thousands of years for the prevention and treatment of GA, demonstrating effective control over serum UA (SUA) levels with fewer side effects. Herein we summarized a total of 541 studies published from 2000 to 2023 in sources including PubMed, Web of Science, the Cochrane Library and Embase, highlighting the therapeutic potential of TCM in treating gout and GA, particularly in combination with modern medical strategies. This review focuses on TCM formulas, Chinese herbal extracts, and active compounds derived from TCM, providing an overview of recent clinical application and the pharmacological research based on animal models and cellular systems. Particularly, the current review categorized the clinical and experimental evidence into the strategies for improving hyperuricemia, decreasing the sudden onset of acute GA and retarding chronic GA progression, supplied further coherent reference and enlightenment for clinicians, investigators of natural product chemistry, researchers in TCM and pharmacology. We hope this article will inspire the development of novel formulas and molecular entities for the treatment of gout and GA.

Untargeted metabolomics analysis of the urinary metabolic signature of acute and chronic gout

BACKGROUND

Gout is a common kind of inflammatory arthritis with metabolic disorders. However, the detailed pathogenesis of gout is complex and not fully clear. We investigated the urine metabolic profiling of gout patients by ultra-performance liquid chromatograph quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS).

METHOD

Urine metabolites were extracted from 26 acute gout patients, 31 chronic gout patients, and 32 healthy controls. Metabolite extracts were analyzed by UPLC-Q-TOF-MS for untargeted metabolomics. The peak area of creatinine was used to correct the content variations of urine samples for the semi-quantitative analysis. The value of variable importance in the projection (VIP) was obtained through the orthogonal partial least squares-discrimination analysis (OPLS-DA), and several differential metabolites were screened out.

RESULTS

The potential metabolic markers of gout in different stages were found based on the t-test. Finally, 18 different metabolites were identified through Human Metabolome Database (HMDB) and Targeted-MS/MS. The receiver operating characteristic (ROC) curve results revealed that all the screened biomarkers exerted high accuracy and diagnostic value. Pathway analysis indicated that the significantly different metabolites were mainly involved in purine metabolism and amino acid metabolism.

CONCLUSION

The identified potential biomarkers are mainly involved in purine metabolism and amino acid metabolism, which leads us to further explore the pathogenesis of gout. This will lead us to further explore the pathogenesis of gout and provide the basis and ideas for the prevention and treatment of gout.

Systemic inflammation response index association with gout in hyperuricemic adults: NHANES 2007-2018

Background

Hyperuricemia is the underlying condition of gout. Previous studies have indicated that specific strategies may be effective in preventing the progression of hyperuricemia to gout. However, there is a lack of widely applicable methods for identifying high-risk populations for gout. Gout is linked to inflammation, especially in the hyperuricemic population. Systemic inflammation response index (SIRI) is a novel method for evaluating an individual's systemic inflammatory activity. However, the association between SIRI and gout in the hyperuricemic population has not been studied.

Methods

The study utilized data from the National Health and Nutrition Examination Survey (NHANES) 2007-2018.SIRI was log2-transformed before analysis. Multivariable logistic regression, subgroup analysis, and smooth curve fitting were employed to comprehensively evaluate the correlation between SIRI and gout prevalence in the hyperuricemic population. Additionally, we compared SIRI with other inflammatory markers.

Result

A total of 6,732 hyperuricemic patients were included, of which 3,764 were men. After adjusting for all covariates, SIRI was found to be significantly positively correlated with gout prevalence in the female group ([OR = 1.385, 95% CI (1.187, 1.615), p < 0.001]), and its diagnostic performance was superior to other inflammatory markers. In the male group, the correlation between log2-SIRI and gout prevalence was not significant ([OR = 0.994, 95% CI (0.892, 1.108), p = 0.916]). But there were significant positive correlations in the 20-45 age group ([OR = 1.362, 95% CI (1.021, 1.818), p = 0.036]). Subgroup analyses revealed that the results were largely consistent when the individuals were divided into different subgroups (FDR adjusted p for interaction >0.05 for all).

Conclusion

Our study suggests that the Systemic Inflammation Response Index (SIRI) has potential as a predictive marker for gout risk in hyperuricemic women. However, given the higher gout prevalence in men, the potential of SIRI as a predictive marker for gout risk in this population may be limited. Subgroup analyses, however, indicated that the relationship between SIRI and gout prevalence, as well as its statistical significance, varied across different age groups. Future research could further explore this association by investigating the relationship between SIRI and gout prevalence in different age cohorts.

The pathogenesis of gout

Gout is the most common inflammatory arthritis in adults, associated with hyperuricemia and the chronic deposition of monosodium urate (MSU) crystals. Hyperuricemia results from increased production of uric acid and decreased excretion by the kidneys and intestines. Urate excretion is regulated by a group of urate transporters, and decreased renal or intestinal excretion is the primary mechanism of hyperuricemia in most people. Genetic variability in these urate transporters is strongly related to variances in serum urate levels. Not all individuals with hyperuricemia show deposition of MSU crystals or develop gout. The initiation of the inflammatory response to MSU crystals is mainly mediated by the nucleotide-binding oligomerization domain-, leucine-rich repeat- and pyrin domain-containing protein 3 (NLRP3) inflammasome. The activated NLRP3 inflammasome complex cleaves pro-interleukin-1β (IL-1β) into its active form, IL-1β, which is a key mediator of the inflammatory response in gout. IL-1β leads to the upregulation of cytokines and chemokines, resulting in the recruitment of neutrophils and other immune cells. Neutrophils recruited to the site of inflammation also play a role in resolving inflammation. Aggregated neutrophil extracellular traps (NETs) trap and degrade cytokines and chemokines through NET-bound proteases, promoting the resolution of inflammation. Advanced gout is characterized by tophi, chronic inflammatory responses, and structural joint damage. Tophi are chronic foreign body granuloma-like structures containing collections of MSU crystals encased by inflammatory cells and connective tissue. Tophi are closely related to chronic inflammation and structural damage.

Bioinformatics and molecular docking reveal Cryptotanshinone as the active anti-inflammation component of Qu-Shi-Xie-Zhuo decoction by inhibiting S100A8/A9-NLRP3-IL-1β signaling

BACKGROUND

Gout is a common type of arthritis marked by monosodium urate (MSU) crystal deposition in joints, triggering an inflammatory response. Qu-Shi-Xie-Zhuo (QSXZ), a traditional Chinese medicine (TCM) formula, has been clinically used for the treatment of gouty arthritis (GA).

PURPOSE

The study sought to examine the impact of QSXZ on GA and to delve into the pharmacological mechanisms that underlie its effects.

METHODS

The chemical constituents of QSXZ were analyzed through UPLC-MS. MSU-induced acute gouty arthritis (AGA) and subcutaneous (SC) air pouch models in mice were employed to evaluate the anti-inflammatory properties of QSXZ and its primary active compound, Cryptotanshinone (CTS). To investigate the therapeutic mechanisms of QSXZ, we used MS-based network pharmacology, transcriptomic analysis, molecular docking and multiscale bioassays.

RESULTS

Treatment of QSXZ revealed a significant reduction of inflammatory cell infiltration and the expression of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin -1β (IL-1β). Based on UPLC/MS/MS results, 49 components were considered the active ingredients of QSXZ. Network pharmacology analysis indicated that QSXZ regulates multiple inflammation-related pathways. Subsequent transcriptomic analysis showed that QSXZ regulates gene expression of S100A8 and S100A9. Our investigation observed an increased expression of S100A8 and S100A9 in monocytes derived from gout patients. Molecular docking and molecular dynamics simulation analysis revealed the binding pattern and interaction between QSXZ active compound CTS and S100A8/A9, and subsequent surface plasmon resonance (SPR) and cell thermal shift assay (CETSA) experiments verified the direct interaction between them. To investigate the mechanisms of action, we conducted RT-PCR, Western blotting, immunohistochemistry, flow cytometry, and measured the inflammatory response. Our findings highlight the pathogenic role of S100A8/A9 mediated TLR4-NLRP3 axis in gout and review outstanding therapeutic effects of QSXZ and its primary active compound CTS on MSU-induced experimental models.

CONCLUSIONS

In summary, this study substantiates the therapeutic potential of QSXZ and its primary active compound CTS, as promising alternative treatments for GA. Our findings provide valuable insight into the critical pharmacological mechanism of QSXZ in regulating inflammation, highlighting its potential therapeutic effects in GA management.

Quantitative Assessment of Baseline Serum HDL-C to Predict Gout Flares During Urate-Lowering Therapy Initiation: A Prospective Cohort Study

Purpose

Previous studies have linked high-density lipoprotein cholesterol (HDL-C) to gout, but little is known about the dose-effect relationship between serum HDL-C levels and gout flares. This study aimed to quantify the association between the two during urate-lowering therapy initiation and develop a regression equation to predict gout flares.

Patients and Methods

We conducted a prospective, observational, single-center cohort study of men with gout. Patients were identified and grouped according to the level of serum HDL-C (1.16 mmol/L) at baseline and followed-up every four weeks until 12 weeks.

Results

A total of 394 participants completed the study (203 in the low HDL-C group; 191 in the high HDL-C group). The proportion of participants with gout flares in the low HDL-C group was significantly higher than in the high HDL-C group after 12 weeks follow-up (52.2% versus 35.6%, P=0.001). Patients with lower serum HDL-C level had higher risk of gout flares analyzed by restricted cubic spline and when serum HDL-C level = 1.15mmol/L, flareHR = 1. When combined with well-known risk factors, serum HDL-C predicted gout flares with an area under curve (AUC) of 0.75 (95% CI=0.70-0.80). Based on the logistic regression coefficients, we derived the following regression equation: Logit (P)= -2.282+0.05× [disease duration]+1.015× [recurrent flares in the last year]+0.698× [palpable tophus]+0.345× [serum urate]-1.349×[serum HDL-C].

Conclusion

Patients with gout presented a negative linear relationship between serum HDL-C and gout flares. Together with common clinical indicators, the AUC for gout flare prediction increased to 0.75. For patients with gout, remaining serum HDL-C level above 1.15 mmol/L may reduce the risk of gout flares.

Association of sedentary behaviour with gout and the interaction effect of hyperuricemia: a cross-sectional study from 2007 to 2018

BACKGROUND

The increasing prevalence of sedentary lifestyles has raised concerns about its health impacts. This study sought to explore the association between sedentary behaviour and gout, a condition historically linked with affluent lifestyles but now increasingly prevalent in the general population.

METHODS

Utilizing data from the National Health and Nutrition Examination Survey database, this cross-sectional study analysed 34,526 participants from 2007 to 2018. The study focused on identifying any potential relationships between sedentary behaviour and the incidence of gout while adjusting for various confounders.

RESULTS

The study found a significant increase in the prevalence of gout from 2017 to 2018 and identified a reversed L-shaped relationship between sedentary behaviour and gout (OR = 1.03; 95% CI 1.00, 1.06; P = 0.0198), especially among individuals without hyperuricemia. Body Mass Index (BMI) may act as a key mediator in the relationship between sedentary behaviour and gout. In those with hyperuricemia, more than 12 h per day of sedentary behaviour substantially increased the prevalence of gout.

CONCLUSION

Prolonged sedentary behaviour emerged as an independent risk factor for gout. This association was particularly pronounced in individuals without hyperuricemia, suggesting the need for lifestyle modifications in this group. However, further research using prospective cohort studies is necessary to establish causality.

Hypocrellin A from an ethnic medicinal fungus protects against NLRP3-driven gout in mice by suppressing inflammasome activation

Abnormal activation of NLRP3 inflammasome causes the progression of gout, and no small-molecule inhibitor of NLRP3 has been approved yet for clinical use. In this study we established a nigericin-induced inflammasome activation cell model for screening of a natural product library by measuring IL-1β secretion in cell supernatants. Among 432 compounds tested, we found that hypocrellin A (HA), one of the major active components of a traditional ethnic medicinal fungus Hypocrella bambusea in the Northwest Yunnan of China, exhibited the highest inhibition on IL-1β production (IC50 = 0.103 μM). In PMA-primed THP-1 cells or bone marrow derived macrophages (BMDMs) treated with multiple stimuli (nigericin, ATP or MSU), HA dose-dependently suppressed the activation of NLRP3 inflammasome, reducing the subsequent release of inflammatory cytokines and LDH. Furthermore, the suppression of inflammasome activation by HA was specific to NLRP3, but not to AIM2 or NLRC4. In LPS-primed BMDMs treated with nigericin, HA inhibited ASC oligomerization and speckle formation, and blocked the NLRP3-NEK7 interaction during inflammasome assembly without influencing the priming stage. Moreover, we demonstrated that HA directly bound to the NACHT domain of NLRP3, and that Arg578 and Glu629 were the critical residues for HA binding to NLRP3. In MSU-induced peritonitis and acute gouty arthritis mouse models, administration of HA (10 mg/kg, i.p., once or twice daily) effectively suppressed the inflammatory responses mediated by NLRP3 inflammasome. We conclude that HA is a broad-spectrum and specific NLRP3 inhibitor, and a valuable lead compound to develop novel therapeutic inhibitors against NLRP3-driven diseases. This study also elucidates the anti-inflammation mechanisms and molecular targets of HA, a major active component in medicinal fungus Hypocrella bambusea that has been long used by Chinese ethnic groups.

Neutrophil diversity and function in health and disease

Neutrophils, the most abundant type of granulocyte, are widely recognized as one of the pivotal contributors to the acute inflammatory response. Initially, neutrophils were considered the mobile infantry of the innate immune system, tasked with the immediate response to invading pathogens. However, recent studies have demonstrated that neutrophils are versatile cells, capable of regulating various biological processes and impacting both human health and disease. Cytokines and other active mediators regulate the functional activity of neutrophils by activating multiple receptors on these cells, thereby initiating downstream signal transduction pathways. Dysfunctions in neutrophils and disruptions in neutrophil homeostasis have been implicated in the pathogenesis of numerous diseases, including cancer and inflammatory disorders, often due to aberrant intracellular signaling. This review provides a comprehensive synthesis of neutrophil biological functions, integrating recent advancements in this field. Moreover, it examines the biological roles of receptors on neutrophils and downstream signaling pathways involved in the regulation of neutrophil activity. The pathophysiology of neutrophils in numerous human diseases and emerging therapeutic approaches targeting them are also elaborated. This review also addresses the current limitations within the field of neutrophil research, highlighting critical gaps in knowledge that warrant further investigation. In summary, this review seeks to establish a comprehensive and multidimensional model of neutrophil regulation, providing new perspectives for potential clinical applications and further research.

Causal relationship between inflammatory proteins, immune cells, and gout: a Mendelian randomization study

Prior research has documented the association between certain circulating inflammatory proteins/immune cells and gout. However, the reliability of these associations remains contentious due to the constraints of conventional observational methodologies. This investigation seeks to reassess the causative link between circulating inflammatory proteins/immune cells and gout through the application of Mendelian randomization (MR). The study included 3576 individuals of European ancestry with gout, immune cell data from the GWAS summary of 3757 Sardinians, and circulating inflammatory protein data from 14,824 European ancestry participants for MR analysis. The principal approach employed was inverse variance weighted analysis to investigate the causal relationship between exposure and outcomes. The results indicate that CD28 on CD39+ CD4+ T cells may be associated with a reduced risk of gout. Additionally, CD45RA+ CD28- CD8bright T cells may also be associated with a reduced risk of gout. In contrast, DN (CD4-CD8-) T cells and IL-12β may increase the risk of gout. Some inflammatory proteins and immune cells show potential causal associations with gout. Nevertheless, additional experimental verification is warranted to assess the underlying mechanisms and confirm the causative role of these immune factors in gout pathogenesis.

Unraveling the impact of miRNAs on gouty arthritis: diagnostic significance and therapeutic opportunities

Gouty arthritis is a prevalent inflammatory illness. Gout attacks begin when there is an imbalance in the body's uric acid metabolism, which leads to urate buildup and the development of the ailment. A family of conserved, short non-coding RNAs known as microRNAs (miRNAs) can regulate post-transcriptional protein synthesis by attaching to the 3' untranslated region (UTR) of messenger RNA (mRNA). An increasing amount of research is pointing to miRNAs as potential players in several inflammatory diseases, including gouty arthritis. miRNAs may influence the progression of the disease by regulating immune function and inflammatory responses. This review mainly focused on miRNAs and how they contribute to gouty arthritis. It also looked at how miRNAs could be used as diagnostic, prognostic, and potential therapeutic targets.

Investigating the involvement of the NLRP3/ASC/caspase-1 and NF-κb/MAPK pathways in the pathogenesis of gouty arthritis: Insights from irradiated and non-irradiated Trifolium alexandrium L. extracts and some metabolites

ETHNOPHARMACOLOGICAL RELEVANCE

Trifolium alexandrinum L. (TA), has traditionally been used in folk medicine for its anti-inflammatory properties against hyperuricemia and gout. However, the specific mechanisms of action of TA have not been thoroughly studied.

AIM OF THE WORK

This study aimed to evaluate the protective effects of irradiated (TR25) and non-irradiated (TR0) Trifolium alexandrinum L. aqueous extract (TAAE), along with two isolated compounds, caffeine (CAF) and saponin (SAP), in a rat model of acute gouty arthritis (GA).

MATERIALS AND METHODS

The GA model was established by injecting a monosodium urate (MSU) suspension into the knee joint. Synovial tissue pathology was assessed, and levels of TNF-α, IL-6, IL-1β, NF-κB, mTOR, AKT1, PI3K, NLRP3, and ASC were measured by ELISA. mRNA expression of ERK1, JNK, and p-38 MAPK was detected using qRT-PCR, and Caspase-1 protein expression was assessed by immunohistochemical analysis. Knee swelling, uric acid levels, liver and kidney function, and oxidative stress markers were also evaluated.

RESULTS

TAAE analysis identified 170 compounds, with 73 successfully identified using LC-HR-MS/MS, including caffeine citrate and theasapogenol B glycoside as the main constituents. The studied materials demonstrated significant protective effects against GA. TR25 administration significantly mitigated knee joint circumference compared to other treatments. It demonstrated potential in alleviating hyperuricemia, renal and hepatic impairments induced by MSU crystals. TR25 also alleviated oxidative stress and reduced levels of IL1β, IL-6, TNF-α, and NF-κB. Weak Caspase-1 immune-positive staining was observed in the TR25 group. TR25 decreased NLRP3 and ASC expression, reducing inflammatory cytokine levels in GA. It effectively inhibited the PI3K, AKT, and mTOR signaling pathways, promoting autophagy. Additionally, TR25 suppressed ERK1, JNK, and p-38 MAPK gene expression in synovial tissue. These effects were attributed to various components in TAAE, such as flavonoids, phenolic acids, tannins, alkaloids, and triterpenes.

CONCLUSION

Importantly, irradiation (25 KGy) enhanced the antioxidant effects and phtchemical contents of TAAE. Additionally, TR0, TR25, CAF, and SAP exhibited promising protective effects against GA, suggesting their therapeutic potential for managing this condition. These effects were likely mediated through modulation of the NLRP3/ASC/Caspase-1 and ERK/JNK/p-38 MAPK signaling pathways, as well as regulation of the PI3K/AKT/mTOR pathway. Further research is warranted to fully elucidate the underlying mechanisms and optimize their clinical applications.

Alterations of Hepatic Lipidome Occur in a Gouty Model: A Shotgun Lipidomics Study

Background

Liver injury, such as nonalcoholic fatty liver disease, is a common symptom observed in patients with gout/hyperuricaemia. However, the exact mechanisms are still unclear. There is ongoing controversy about whether representative agents like colchicine and febuxostat, commonly used to manage gout, could also help prevent the liver injury. Liver plays a crucial role in uric acid (UA) production and lipid metabolism. Thus, the study aimed to investigate the aberrant lipid metabolism in the liver during injury and the effects of these drugs.

Methods

An advanced multi-dimensional mass spectrometry-based shotgun lipidomics technology was employed for class-targeted lipid analysis of cellular lipidomes in hepatic tissue of a gouty model induced by a combination of monosodium urate crystals and high-fat diet with or without treatment with colchicine and febuxostat. Serum UA, blood urea nitrogen, creatinine, proinflammatory cytokines, expression of AMP-activated protein kinase protein, footpad histopathology, and footpad swelling and pain threshold of these mice were assessed to evaluate the progression of gout.

Results

Lipidomics analysis clearly demonstrated that the ectopic fat accumulation as well as changes in fatty acyls composition in TAG pool, impaired mitochondrial function resulted by decreased tetra 18:2 cardiolipin, and reduced 4-hydroxyalkenal bioavailability in liver tissue could contribute to liver damage to the gouty model. Treatment with colchicine or febuxostat not only ameliorated gouty symptoms but also corrected these abnormal hepatic lipid metabolism patterns.

Conclusion

This study shed light on underlying mechanism(s) for liver injury in gout/hyperuricaemia and suggested that administration of drugs like colchicine and febuxostat could prevent liver injury.

Transcutaneous auricular vagus nerve stimulation mitigates gouty inflammation by reducing neutrophil infiltration in BALB/c mice

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

The decreased serum levels of interleukin-38 in patients with gout and its clinical significance

Background

Interleukin (IL)-38 is a newly discovered anti-inflammatory cytokine. However, its concentration and clinical significance in patients with gout remain unclear. This study aimed to investigate the levels of IL-38 in patients with gout and evaluate their clinical significance.

Methods

Thirty-two patients with active gout, 27 patients with inactive gout, and 20 negative controls (NCs) were included in the study. Clinical parameters, including white blood cell count, C-reactive protein, serum amyloid A, erythrocyte sedimentation rate, uric acid, urea, creatinine, alanine aminotransferase, aspartate aminotransferase, glutamyl transpeptidase, and glycoserated serum protein, were obtained from laboratory tests of blood samples. The serum concentration of IL-38 was determined using enzyme-linked immunosorbent assay. Spearman's correlation analysis and receiver operating characteristic curve assessments were used to investigate the role and diagnostic value of IL-38 in gout.

Results

Patients with active and inactive gout exhibited significantly lower serum IL-38 levels than NCs. No significant differences were observed between the two gout groups. A negative correlation was observed between IL-38 and white blood cell counts, whereas a positive correlation was found between IL-38 and creatinine levels. Furthermore, IL-38, either alone or in combination with uric acid, demonstrated substantial diagnostic potential.

Conclusion

The findings suggest that the decreased serum levels of IL-38 in patients with gout compared to that in NCs indicates that IL-38 may have immunomodulatory effects on gout inflammation and possesses clinical application value.

Short Link N Modulates Inflammasome Activity in Intervertebral Discs Through Interaction with CD14

Intervertebral disc degeneration and pain are associated with the nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing 3 (NLRP3) inflammasome activation and the processing of interleukin-1 beta (IL-1β). Activation of thehm inflammasome is triggered by Toll-like receptor stimulation and requires the cofactor receptor cluster of differentiation 14 (CD14). Short Link N (sLN), a peptide derived from link protein, has been shown to modulate inflammation and pain in discs in vitro and in vivo; however, the underlying mechanisms remain elusive. This study aims to assess whether sLN modulates IL-1β and inflammasome activity through interaction with CD14. Disc cells treated with lipopolysaccharides (LPS) with or without sLN were used to assess changes in Caspase-1, IL-1β, and phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB). Peptide docking of sLN to CD14 and immunoprecipitation were performed to determine their interaction. The results indicated that sLN inhibited LPS-induced NFκB and Caspase-1 activation, reducing IL-1β maturation and secretion in disc cells. A significant decrease in inflammasome markers was observed with sLN treatment. Immunoprecipitation studies revealed a direct interaction between sLN and the LPS-binding pocket of CD14. Our results suggest that sLN could be a potential therapeutic agent for discogenic pain by mitigating IL-1β and inflammasome activity within discs.

Mechanism of macrophages in gout: Recent progress and perspective

Gout represents an autoinflammatory disorder instigated by monosodium urate crystals. Its primary manifestation involves the recruitment of diverse immune cell populations, including neutrophils and macrophages. Macrophages assume a pivotal role in the initiation of acute gouty inflammation and subsequent inflammatory cascades. However, recent investigations have revealed that the impact of macrophages on gout is nuanced, extending beyond a solely detrimental influence. Macrophages, characterized by different subtypes, exhibit distinct functionalities that either contribute to the progression or regression of gout. A strategy aimed at modulating macrophage polarization, rather than merely inhibiting inflammation, holds promise for enhancing the efficacy of acute gout treatment. This review centres on elucidating potential mechanisms underlying macrophage polarization in the onset and resolution of gouty inflammation, offering novel insights into the immune equilibrium of macrophages in the context of gout.

Association of visceral adipose tissue with gout: Observational and Mendelian randomization analyses

BACKGROUND

The causal relationship between visceral adipose tissue (VAT) and gout is still unclear. We aimed to examine the potential association between them using observational and Mendelian randomization (MR) analyses.

METHODS

In the observational analyses, a total of 11,967 participants (aged 39.5 ± 11.5 years) were included from the National Health and Nutrition Examination Survey. Logistic regression models were used to investigate the association between VAT mass and the risk of gout. In two-sample MR analyses, 211 VAT mass-related independent genetic variants (derived from genome-wide association studies in 325,153 UK biobank participants) were used as instrumental variables. The random-effects inverse-variance weighted (IVW) method was used as the primary analysis. Additional sensitivity analyses were also performed to validate our results.

RESULTS

Observational analyses found that an increase in VAT mass (per standard deviation) was associated with a higher risk of gout after controlling for confounding factors (odds ratio [OR] = 1.27, 95% confidence intervals [CI] = 1.11-1.45). The two-sample MR analyses demonstrated a causal relationship between increased VAT mass and the risk of gout in primary analyses (OR = 1.78, 95% CI = 1.57-2.03). Sensitivity analyses also showed similar findings, including MR-Egger, weighted median, simple mode, weighted mode, and leave-one-out analyses.

CONCLUSIONS

Observational analyses showed a robust association of VAT mass with the risk of gout. Meanwhile, MR analyses also provided evidence of a causal relationship between them. In summary, our findings suggested that targeted interventions for VAT mass may be beneficial to prevent gout.

Pathophysiological role and potential drug target of NLRP3 inflammasome in the metabolic disorders

NLRP3 plays a role in the development of autoinflammatory diseases. NLRP3, ASC, and Caspases 1 or 8 make up the NLRP3 inflammasome, which is an important part of innate immune system. The NLRP3 inflammasome-mediated inflammatory cytokines may also participate in metabolic disorders, such as diabetes, hyperlipidemia, atherosclerosis, non-alcoholic fatty liver disease, and gout. Hence, an overview of the NLRP3 regulation in these metabolic diseases and the potential drugs targeting NLRP3 is the focus of this review.

Microneedle transdermal drug delivery as a candidate for the treatment of gouty arthritis: Material structure, design strategies and prospects

Gouty arthritis (GA) is caused by monosodium urate (MSU) crystals deposition. GA is difficult to cure because of its complex disease mechanism and the tendency to reoccur. GA patients require long-term uric acid-lowering and anti-inflammatory treatments. In the past ten years, as a painless, convenient and well-tolerated new drug transdermal delivery method, microneedles (MNs) administration has been continuously developed, which can realize various drug release modes to deal with various complex diseases. Compared with the traditional administration methods (oral and injection), MNs are more conducive to the long-term independent treatment of GA patients because of their safe, efficient and controllable drug delivery ability. In this review, the pathological mechanism of GA and common therapeutic drugs for GA are summarized. After that, MNs drug delivery mechanisms were summarized: dissolution release mechanism, swelling release mechanism and channel-assisted release mechanism. According to drug delivery patterns of MNs, the mechanisms and applications of rapid-release MNs, long-acting MNs, intelligent-release MNs and multiple-release MNs were reviewed. Additionally, existing problems and future trends of MNs in the treatment of GA were also discussed. STATEMENT OF SIGNIFICANCE: Gout is an arthritis caused by metabolic disease "hyperuricemia". Epidemiological studies show that the number of gouty patients is increasing rapidly worldwide. Due to the complex disease mechanism and recurrent nature of gout, gouty patients require long-term therapy. However, traditional drug delivery modes (oral and injectable) have poor adherence, low drug utilization, and lack of local localized targeting. They may lead to adverse effects such as rashes and gastrointestinal reactions. As a painless, convenient and well-tolerated new drug transdermal delivery method, microneedles have been continuously developed, which can realize various drug release modes to deal with gouty arthritis. In this review, the material structure, design strategy and future outlook of microneedles for treating gouty arthritis will be reviewed.

Triptolide alleviates acute gouty arthritis caused by monosodium urate crystals by modulating macrophage polarization and neutrophil activity

The present study focused on the efficacy and role of triptolide (TPL) in relieving symptoms of acute gouty arthritis (AGA) in vivo and in vitro. The effects of TPL in AGA were investigated in monosodium urate (MSU)-treated rat ankles, RAW264.7 macrophages, and neutrophils isolated from mouse peritoneal cavity. Observation of pathological changes in the ankle joint of rats. Enzyme-linked immunosorbent assay and real-time quantitative polymerase chain reaction (RT-qPCR) were performed to detect the expression levels of inflammatory factors and chemokines. The levels of the indicators of macrophage M1/M2 polarization, and the mechanistic targets of Akt and rapamycin complex 2, were determined via western blotting and RT-qPCR. The expression levels of CD86 and CD206 were detected using immunohistochemistry. Neutrophil migration was observed via air pouch experiments in vivo and Transwell cell migration assay in vitro. Myeloperoxidase (MPO) and Neutrophil elastase (NE) release was analyzed by via immunohistochemistry and immunofluorescence. The expression levels of beclin-1, LC3B, Bax, Bcl-2, and cleaved caspase-3 in neutrophils were determined via western blotting and immunofluorescence. Neutrophil apoptosis was detected using the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Our results suggest that TPL inhibited inflammatory cell infiltration in rat ankle joints and inflammatory factor and chemokine secretion in rat serum, regulated macrophage polarization through the PI3K/AKT signaling pathway, suppressed inflammatory factor and chemokine expression in neutrophils, and inhibited neutrophil migration, neutrophil extracellular trap formation, transitional autophagy, and apoptosis. This suggests that TPL can prevent and treat MSU-induced AGA by regulating macrophage polarization through the PI3K/Akt pathway and modulating neutrophil activity.

Transdermal delivery of iguratimod and colchicine ethosome by dissolving microneedle patch for the treatment of recurrent gout

This study introduces a novel approach of repetitive modeling to simulate the pathological process of recurrent gout attacks in humans. This methodology addresses the instability issues present in rat models of gout, providing a more accurate representation of the damage recurrent gout episodes inflict on human skeletal systems. A soluble nanoneedle system encapsulating colchicine and iguratimod ethosomal formulations was developed. This system aims to modulate inflammatory cytokines and inhibit osteoclast activity, thereby treating inflammatory pain and bone damage associated with recurrent gout. Additionally, a comprehensive evaluation of the microneedles' appearance, morphology, mechanical properties, and penetration capability confirmed their effectiveness in penetrating the stratum corneum. Dissolution tests and skin irritation assessments demonstrated that these microneedles dissolve rapidly without irritating the skin. In vitro permeation studies indicated that transdermal drug delivery via these microneedles is more efficient and incurs lower drug loss compared to traditional topical applications. In vivo pharmacodynamic assessments conducted in animal models revealed significant analgesic and anti-inflammatory effects when both types of microneedles were used together. Further analyses, including X-ray imaging, hematoxylin and eosin (H&E) staining, Safranin-O/fast green staining, tartrate-resistant acid phosphatase staining, and quantification of osteoclasts, confirmed the bone-protective effects of the microneedle combination. In conclusion, the findings of this research underscore the potential of this novel therapeutic approach for clinical application in the treatment of recurrent gout.

Recent advances in the treatment of gout with NLRP3 inflammasome inhibitors

Gout is an autoinflammatory disorder characterized by the accumulation of monosodium urate crystals in joints and other tissues, representing the predominant type of inflammatory arthritis with a notable prevalence and propensity for severe outcomes. The NLRP3 inflammasome, a member of the pyrin domain-containing NOD-like receptor family, exerts a substantial impact on both innate and adaptive immune responses and serves as a pivotal factor in the pathogenesis of gout. In recent years, there has been significant academic and industrial interest in the development of NLRP3-targeted small molecule inhibitors as a promising therapeutic approach for gout. To assess the advancements in NLRP3 inflammasome inhibitors for gout treatment, this review offers a comprehensive analysis and evaluation of current clinical candidates and other inhibitors targeting NLRP3 inflammasome from a chemical structure standpoint, with the goal of identifying more efficacious options for clinical management of gout.

Exploring the Role of Extrachromosomal Circular DNA in Human Diseases

BACKGROUND

Extrachromosomal circular DNA (eccDNA) has emerged as a central focus in molecular biology, with various types being found across species through advanced techniques, including high-throughput sequencing. This dynamic molecule exerts a significant influence on aging and immune function and plays pivotal roles in autoimmune diseases, type 2 diabetes mellitus, cancer, and genetic disorders.

SUMMARY

This comprehensive review investigates the classification, characteristics, formation processes, and multifaceted functions of eccDNA, providing an in-depth exploration of its mechanisms in diverse diseases.

KEY MESSAGES

The goal of this review was to establish a robust theoretical foundation for a more comprehensive understanding of eccDNA, offering valuable insights for the development of clinical diagnostics and innovative therapeutic strategies in the context of related diseases.

Gout risk in adults with pre-diabetes initiating metformin

OBJECTIVE

Despite the strong association between gout and pre-diabetes, the role of metformin in gout among individuals with pre-diabetes remains uncertain. We compared the incidence rates of gout in adults with pre-diabetes starting metformin with those not using antidiabetic treatments.

METHODS

We conducted a new-user, propensity score-matched cohort study using electronic health records from an academic health system (2007-2022). Pre-diabetes was defined based on haemoglobin A1c levels. Metformin users were identified and followed from the first metformin prescription date. Non-users of antidiabetic medications were matched to metformin users based on propensity score and the start of follow-up. The primary outcome was incident gout. Cox proportional hazards models estimated the HR for metformin. Linear regression analyses assessed the association between metformin use and changes in serum urate (SU) or C-reactive protein (CRP).

RESULTS

We identified 25 064 individuals with pre-diabetes and propensity score-matched 1154 metformin initiators to 13 877 non-users. Baseline characteristics were well balanced (all standardised mean differences <0.1). The median follow-up was 3.9 years. The incidence rate of gout per 1000 person-years was lower in metformin users 7.1 (95% CI 5.1 to 10) compared with non-users 9.5 (95% CI 8.8 to 10.2). Metformin initiation was associated with a reduced relative risk of gout (HR 0.68, 95% CI 0.48 to 0.96). No relationship was found between metformin and changes in SU or CRP.

CONCLUSIONS

Metformin use was associated with a reduced risk of gout among adults with pre-diabetes, suggesting that metformin may be important in lowering gout risk in individuals with pre-diabetes.

Neutrophil extracellular traps in homeostasis and disease

Neutrophil extracellular traps (NETs), crucial in immune defense mechanisms, are renowned for their propensity to expel decondensed chromatin embedded with inflammatory proteins. Our comprehension of NETs in pathogen clearance, immune regulation and disease pathogenesis, has grown significantly in recent years. NETs are not only pivotal in the context of infections but also exhibit significant involvement in sterile inflammation. Evidence suggests that excessive accumulation of NETs can result in vessel occlusion, tissue damage, and prolonged inflammatory responses, thereby contributing to the progression and exacerbation of various pathological states. Nevertheless, NETs exhibit dual functionalities in certain pathological contexts. While NETs may act as autoantigens, aggregated NET complexes can function as inflammatory mediators by degrading proinflammatory cytokines and chemokines. The delineation of molecules and signaling pathways governing NET formation aids in refining our appreciation of NETs' role in immune homeostasis, inflammation, autoimmune diseases, metabolic dysregulation, and cancer. In this comprehensive review, we delve into the multifaceted roles of NETs in both homeostasis and disease, whilst discussing their potential as therapeutic targets. Our aim is to enhance the understanding of the intricate functions of NETs across the spectrum from physiology to pathology.

Statin use associated with a reduced risk of hip fracture in patients with gout

Studies show that statins users are at reduced risk of fracture and improved bone mineral density. However, the clinical effectiveness of statin use in patients with gout has not been investigated. This retrospective cohort study used data from Taiwan's National Health Insurance Research Database, consisting of 3443 patients with gout using statins aged 50 years and above and 6886 gout patients of non-statin users matched by sex, age and propensity score. The Cox proportional hazards regression analysis showed that statin use was associated with a reduced risk of hip fracture (adjusted hazard ratio [aHR] = 0.78, 95 % confidence interval [CI] = 0.64-0.94) after controlling for potential confounding factors. The association was significant in both genders aged 50-64 years, with aHRs of near 0.35, but not in the elderly. In addition, women aged 50-64 years who used statins also exhibited a lower risk of vertebral fracture (aHR = 0.70, 95 % CI = 0.50-0.99), but not men. In conclusion, the stating use in gout patients could reduce fracture risk for younger patients. Further research is warranted to confirm these findings.

Neutrophils and extracellular traps in crystal-associated diseases

Crystalline material can cause a multitude of acute and chronic inflammatory diseases, such as gouty arthritis, silicosis, kidney disease, and atherosclerosis. Crystals of various types are thought to cause similar inflammatory responses, including the release of proinflammatory mediators and formation of neutrophil extracellular traps (NETs), processes that further promote necroinflammation and tissue damage. It has become apparent that the intensity of inflammation and the related mechanisms of NET formation and neutrophil death in crystal-associated diseases can vary depending on the crystal type, amount, and site of deposition. This review details new mechanistic insights into crystal biology, highlights the differential effects of various crystals on neutrophils and extracellular trap (ET) formation, and discusses treatment strategies and potential future approaches for crystal-associated disorders.

Hyperuricemia and its related diseases: mechanisms and advances in therapy

Hyperuricemia, characterized by elevated levels of serum uric acid (SUA), is linked to a spectrum of commodities such as gout, cardiovascular diseases, renal disorders, metabolic syndrome, and diabetes, etc. Significantly impairing the quality of life for those affected, the prevalence of hyperuricemia is an upward trend globally, especially in most developed countries. UA possesses a multifaceted role, such as antioxidant, pro-oxidative, pro-inflammatory, nitric oxide modulating, anti-aging, and immune effects, which are significant in both physiological and pathological contexts. The equilibrium of circulating urate levels hinges on the interplay between production and excretion, a delicate balance orchestrated by urate transporter functions across various epithelial tissues and cell types. While existing research has identified hyperuricemia involvement in numerous biological processes and signaling pathways, the precise mechanisms connecting elevated UA levels to disease etiology remain to be fully elucidated. In addition, the influence of genetic susceptibilities and environmental determinants on hyperuricemia calls for a detailed and nuanced examination. This review compiles data from global epidemiological studies and clinical practices, exploring the physiological processes and the genetic foundations of urate transporters in depth. Furthermore, we uncover the complex mechanisms by which the UA induced inflammation influences metabolic processes in individuals with hyperuricemia and the association with its relative disease, offering a foundation for innovative therapeutic approaches and advanced pharmacological strategies.

Nonlinear association between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio and hyperuricemia in cancer patients: evidence from NHANES 2007-2018

BACKGROUND

Evidence shows that cancer patients are more likely to have hyperuricemia (HUA) compared to the general population, with lipid metabolism playing a significant role. However, it is still unclear whether there is a non-linear relationship between the non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and HUA in these patients. This study aims to explore the association between NHHR and HUA in cancer patients.

METHODS

This study included participants from the NHANES database from 2007 to 2018. We used multivariable logistic regression, restricted cubic splines (RCS) analysis, and subgroup analysis to examine the association between NHHR and HUA and gout in cancer patients, as well as to investigate differences in this association among specific subgroups.

RESULTS

A total of 2826 participants were included, with a HUA prevalence of 24.30%. Weighted multivariable logistic regression showed that for each unit increase in NHHR, the odds of HUA in cancer patients increased by 16% (95% confidence interval [CI]: 1.06, 1.29, P = 0.002). When NHHR was divided into tertiles, those in the highest tertile (Q3) had a 1.84 times higher odds of developing HUA compared to those in the lowest tertile (Q1) (95% CI: 1.32, 2.58, P < 0.001). However, there was no significant association with gout. RCS analysis further revealed a significant non-linear positive association, particularly among males. Subgroup analysis and interaction tests indicated a stronger association in cancer patients who did not have a history of stroke.

CONCLUSION

There is a non-linear association between NHHR and HUA in cancer patients.

Research progress of SREBP and its role in the pathogenesis of autoimmune rheumatic diseases

Autoimmune rheumatic diseases comprise a group of immune-related disorders characterized by non-organ-specific inflammation. These diseases include systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), ankylosing spondylitis (AS), gout, among others. Typically involving the hematologic system, these diseases may also affect multiple organs and systems. The pathogenesis of autoimmune rheumatic immune diseases is complex, with diverse etiologies, all associated with immune dysfunction. The current treatment options for this type of disease are relatively limited and come with certain side effects. Therefore, the urgent challenge remains to identify novel therapeutic targets for these diseases. Sterol regulatory element-binding proteins (SREBPs) are basic helix-loop-helix-leucine zipper transcription factors that regulate the expression of genes involved in lipid and cholesterol biosynthesis. The expression and transcriptional activity of SREBPs can be modulated by extracellular stimuli such as polyunsaturated fatty acids, amino acids, glucose, and energy pathways including AKT-mTORC and AMP-activated protein kinase (AMPK). Studies have shown that SREBPs play roles in regulating lipid metabolism, cytokine production, inflammation, and the proliferation of germinal center B (GCB) cells. These functions are significant in the pathogenesis of rheumatic and immune diseases (Graphical abstract). Therefore, this paper reviews the potential mechanisms of SREBPs in the development of SLE, RA, and gout, based on an exploration of their functions.

Stefin B alleviates the gouty arthritis in mice by inducing the M2 polarization of macrophages

The present study aims to explore the therapeutic effect of Stefin B on gouty arthritis (GA) and the polarization of macrophages in mice. Stefin B-overexpressed or knockdown M0 macrophages were constructed. The GA model was established in mice by injecting 25 mg/mL MSU, followed by a single injecting of Stefin B-overexpressing adenovirus vector (GA model + Stefin B OE) or an empty vector (GA model + Stefin B OE NC). Stefin B was found lowly expressed in M1 macrophages. CD206 was markedly upregulated and IL-10 release was signally increased in Stefin B-overexpressed macrophages. In gouty arthritis mice, marked redness and swelling were observed in the ankle joint. Dramatical infiltration of inflammatory cells was observed in the GA model and GA model + Stefin B OE NC groups, which was suppressed in the Stefin B OE group. Increased proportion of F4/80+CD86+ cells observed in GA mice was markedly repressed by Stefin B overexpression, accompanied by the declined level of Caspase-1 and IL-17. Collectively, Stefin B alleviated the GA in mice by inducing the M2 polarization of macrophages.

Managing Gout in Patients with Metabolic Syndrome

Gout is characterized by monosodium urate (MSU) crystal deposition secondary to hyperuricemia. Gout is associated with metabolic syndrome (MetS) and its related comorbid conditions such as cardiovascular disease (CVD). Major advances have been made in the comprehension of the link between MetS and gout. Despite observational studies suggesting an association between MetS-related conditions and hyperuricemia, there is no proof of causality. Most studies using Mendelian randomization did not find hyperuricemia as a causal factor for MetS-related conditions. In contrast, these conditions were found associated with hyperuricemia, which suggests a reverse causality. Among patients with gout, this high CVD risk profile implies the need for systematic screening for MetS-related conditions. Most international guidelines recommend systematic screening for and care of CVD and related risk factors in patients with gout. Some anti-hypertensive agents, such as losartan and calcium channel blockers, are able to decrease serum urate (SU) levels. However, there are potential interactions between gout management therapies and the treatment of metabolic diseases. Some data suggest that anti-inflammatory drugs used for gout flare treatment, such as colchicine or canakinumab, might have benefits for CVD. Regarding the impact of urate-lowering therapies on CVD risk, recent studies found a similar CVD safety profile for allopurinol and febuxostat. Finally, sodium-glucose cotransporter-2 inhibitors are promising for gout because of their ability to decrease SU levels and risk of recurrent flares. In this review, we focus on the clinical challenge of managing MetS in patients with gout, particularly older patients with co-medications.

The alleviatory effects of koumine on MSU-induced gouty arthritis via the TLR4/NF-κB/NLRP3 pathway

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

Cell surface protein-protein interaction profiling for biological network analysis and novel target discovery

The secretome is composed of cell surface membrane proteins and extracellular secreted proteins that are synthesized via secretory machinery, accounting for approximately one-third of human protein-encoding genes and playing central roles in cellular communication with the external environment. Secretome protein-protein interactions (SPPIs) mediate cell proliferation, apoptosis, and differentiation, as well as stimulus- or cell-specific responses that regulate a diverse range of biological processes. Aberrant SPPIs are associated with diseases including cancer, immune disorders, and illness caused by infectious pathogens. Identifying the receptor/ligand for a secretome protein or pathogen can be a challenging task, and many SPPIs remain obscure, with a large number of orphan receptors and ligands, as well as viruses with unknown host receptors, populating the SPPI network. In addition, proteins with known receptors/ligands may also interact with alternative uncharacterized partners and exert context-dependent effects. In the past few decades, multiple varied approaches have been developed to identify SPPIs, and these methods have broad applications in both basic and translational research. Here, we review and discuss the technologies for SPPI profiling and the application of these technologies in identifying novel targets for immunotherapy and anti-infectious agents.

Chinese classical decoction Wuwei Xiaodu Drink alleviates gout arthritis by suppressing NLRP3-Mediated inflammation

Background: Wuwei Xiaodu Drink (WWXDD), a classical decoction of traditional Chinese medicine, has been clinically used for the treatment of gout in China for many years. This study aimed to demonstrate the efficacy of WWXDD in treating gout flares and elucidate its underlying therapeutic mechanism. Methods: A randomized control trial was conducted to compare the effectiveness of WWXDD with low-dose colchicine in gout arthritis. The primary outcome was the clinical response rate on the 7th day, and joint syndrome score and serological tests were secondary outcome measures and were compared in the two groups on the 1st and 7th day. Then we used a network pharmacology approach to investigate the possible mechanism of WWXDD in treating gout, and the effects of WWXDD on the MSU-induced rat model were observed. Results: In the clinical trial, a total of 78 participants completed the study, and the results demonstrated comparable clinical complete response rates, joint symptom scores, and serological test outcomes between the two groups on the 7th day. Network pharmacology analysis identified 51 core genes that target gout and WWXDD interactions. Notably, strong significant correlations were observed with inflammation cytokine genes and metabolism-related genes. Furthermore, it was found that WWXDD reduced gene expression levels of inflammation cytokines including IL-1β, TNF, and IL-18 in an MSU-induced rat model while increasing IL-10 expression. Additionally, WWXDD decreased insulin gene expression in this model. Moreover, WWXDD exhibited a reduction in both gene and protein expressions associated with the NLRP3-mediated inflammatory pathway in inflamed joints of rats. Conclusion: The results of the present study suggested the anti-inflammatory effects of WWXDD in the treatment of gouty arthritis, partially through inhibiting NLRP3 inflammasome activation. Clinical Trial Registration: ClinicalTrials.gov, identifier ChiCTR2100047807.

Astilbin inhibited neutrophil extracellular traps in gouty arthritis through suppression of purinergic P2Y6 receptor

BACKGROUND

Gouty arthritis (GA), a common inflammatory condition triggered by monosodium urate crystal accumulation, often necessitates safer treatment alternatives due to the limitations of current therapies. Astilbin, a flavonoid from Smilax glabra Roxb, has demonstrated potential in traditional Chinese medicine for its anti-inflammatory properties. However, the anti-GA effect and its underlying mechanism have not been fully elucidated.

PURPOSE

This study aimed to investigate the therapeutic potential of astilbin in GA, focusing on its effects on neutrophil extracellular traps (NETs), as well as the potential molecular target of GA both in vitro and in vivo.

STUDY DESIGN

Firstly, astilbin inhibited the citrullinated histone H3 (Cit h3) protein levels and reduced the NETs formation in neutrophils stimulated by monosodium urate (MSU). Secondly, we wondered the effect of astilbin on migration of neutrophils and dimethyl-sulfoxide (DMSO)-differentiated HL-60 (dHL-60) cells under the stimulation of MSU. Then, the effect of astilbin on suppressing NETs through purinergic P2Y6 receptor (P2Y6R) and Interlukin-8 (IL-8)/ CXC chemokine receptor 2 (CXCR2) pathway was investigated. Also, the relationship between P2Y6R and IL-8/CXCR2 was explored in dHL-60 cells under stimulation of MSU. Finally, we testified the effect of astilbin on reducing NETs in GA through suppressing P2Y6R and then down-regulating IL-8/CXCR2 pathway.

METHODS

MSU was used to induce NETs in neutrophils and dHL-60 cells. Real-time formation of NETs and migration of neutrophils were monitored by cell living imaging with or without MSU. Then, the effect of astilbin on NETs formation, P2Y6R and IL-8/CXCR2 pathway were detected by immunofluorescence (IF) and western blotting. P2Y6R knockdown dHL-60 cells were established by small interfering RNA to investigate the association between P2Y6R and IL-8/CXCR2 pathway. Also, plasmid of P2Y6R was used to overexpress P2Y6R in dHL-60 cells, which was employed to explore the role of P2Y6R in astilbin inhibiting NETs. Within the conditions of knockdown and overexpression of P2Y6R, migration and NETs formation were assessed by transmigration assay and IF staining, respectively. In vivo, MSU-induced GA mice model was established to assess the effect of astilbin on inflammation by haematoxylin-eosin and ELISA. Additionally, the effects of astilbin on neutrophils infiltration, NETs, P2Y6R and IL-8/CXCR2 pathway were analyzed by IF, ELISA, immunohistochemistry (IHC) and western blotting.

RESULTS

Under MSU stimulation, astilbin significantly suppressed the level of Cit h3 and NETs formation including the fluorescent expressions of Cit h3, neutrophils elastase, myeloperoxidase, and intra/extracellular DNA. Also, results showed that MSU caused NETs release in neutrophils as well as a trend towards recruitment of dHL-60 cells to MSU. Astilbin could markedly decrease expressions of P2Y6R and IL-8/CXCR2 pathway which were upregulated by MSU. By silencing P2Y6R, the expression of IL-8/CXCR2 pathway and migration of dHL-60 cells were inhibited, leading to the suppression of NETs. These findings indicated the upstream role of P2Y6R in the IL-8/CXCR2 pathway. Moreover, overexpression of P2Y6R was evidently inhibited by astilbin, causing a downregulation in IL-8/CXCR2 pathway, migration of dHL-60 cells and NETs formation. These results emphasized that astilbin inhibited the IL-8/CXCR2 pathway primarily through P2Y6R. In vivo, astilbin administration led to marked reductions in ankle swelling, inflammatory infiltration as well as neutrophils infiltration. Expressions of P2Y6R and IL-8/CXCR2 pathway were evidently decreased by astilbin and P2Y6R inhibitor MRS2578 either alone or in combination. Also, astilbin and MRS2578 showed notable effect on reducing MSU-induced NETs formation and IL-8/CXCR2 pathway whether used alone or in combination, parallelly demonstrating that astilbin decreased NETs formation mainly through P2Y6R.

CONCLUSION

This study revealed that astilbin suppressed NETs formation via downregulating P2Y6R and subsequently the IL-8/CXCR2 pathway, which evidently mitigated GA induced by MSU. It also highlighted the potential of astilbin as a promising natural therapeutic for GA.

The impact of AIM2 inflammasome-induced pyroptosis on acute gouty arthritis and asymptomatic hyperuricemia patients

Objective

This study aimed to evaluate the role of absent in melanoma 2 (AIM2) inflammasome-mediated pyroptosis in the pathogenesis of acute gouty arthritis (AGA) and asymptomatic hyperuricemia(AHU).

Methods

A cohort of 30 AGA patients, 30 AHU individuals, and 30 healthy controls (HC) was assembled. Demographic and biochemical data, along with blood samples, were collected. Serum double-stranded DNA (dsDNA) levels were quantified using a fluorescent assay. Transcriptomic and proteomic analysis of AIM2, Caspase-1, GSDMD, IL-1β, and IL-18 in peripheral blood mononuclear cells was performed using qRT-PCR and Western blot. Enzyme-linked immunosorbent assay (ELISA) was employed to measure serum IL-1β and IL-18. Spearman correlation analysis was utilized to assess relationships between variables.

Results

Both AGA and AHU groups demonstrated elevated metabolic indicators and serum levels of dsDNA, IL-1β, and IL-18 compared to the HC group. AGA patients exhibited higher inflammatory markers than the AHU group. In the AGA group, there was a significant increase in the mRNA and protein levels of AIM2, Caspase-1, GSDMD, IL-1β, and IL-18 (P<0.05 to P<0.001). The AHU group showed higher AIM2, Caspase-1, GSDMD, and IL-18 mRNA levels than the HC group (P<0.001 to P<0.01), with a non-significant increase in AIM2, GSDMD, and IL-1β proteins (P>0.05). In contrast, Caspase-1 and IL-18 proteins were significantly higher in the AHU group (P<0.05). Notable correlations were observed between AIM2 protein expression and levels of Caspase-1 and GSDMD in both AGA and AHU groups. In the AGA group, AIM2 protein correlated with IL-1β, but not in the AHU group. The AIM2 protein in the AHU group was positively associated with IL-18, with no such correlation in the AGA group.

Conclusion

AIM2 inflammasome may play a role in the inflammatory processes of AGA and AHU and that its activation may be related to the pyroptosis pathway.

Macrophage-Biomimetic Nanoplatform-Based Therapy for Inflammation-Associated Diseases

Inflammation-associated diseases are very common clinically with a high incidence; however, there is still a lack of effective treatments. Cell-biomimetic nanoplatforms have led to many breakthroughs in the field of biomedicine, significantly improving the efficiency of drug delivery and its therapeutic implications especially for inflammation-associated diseases. Macrophages are an important component of immune cells and play a critical role in the occurrence and progression of inflammation-associated diseases while simultaneously maintaining homeostasis and modulating immune responses. Therefore, macrophage-biomimetic nanoplatforms not only inherit the functions of macrophages including the inflammation tropism effect for targeted delivery of drugs and the neutralization effect of pro-inflammatory cytokines and toxins via membrane surface receptors or proteins, but also maintain the functions of the inner nanoparticles. Macrophage-biomimetic nanoplatforms are shown to have remarkable therapeutic efficacy and excellent application potential in inflammation-associated diseases. In this review, inflammation-associated diseases, the physiological functions of macrophages, and the classification and construction of macrophage-biomimetic nanoplatforms are first introduced. Next, the latest applications of different macrophage-biomimetic nanoplatforms for the treatment of inflammation-associated diseases are summarized. Finally, challenges and opportunities for future biomedical applications are discussed. It is hoped that the review will provide new ideas for the further development of macrophage-biomimetic nanoplatforms.

Co-delivery of indomethacin and uricase as a new strategy for inflammatory diseases associated with high uric acid

Uric acid is the final metabolite in humans. High level of uric acid chronically induces urate deposition, aggravates kidney damage, and concomitantly causes an increase in inflammatory factors. Alleviating acute inflammation and decreasing uric acid levels are the key points in the treatment of inflammatory diseases associated with high uric acid. However, a drug delivery system that combines anti-inflammatory and uric acid reduction functions at the same time remains a challenge to be settled. Here, we designed a nanocrystal-based co-delivery platform, IND Nplex, characterized by loading of indomethacin (IND) and uricase. Compared with free IND or uricase, IND Nplex possessed a better anti-inflammatory effect by restraining the release of inflammation-related factors in vitro. In addition, pharmacokinetic and biodistribution studies revealed that IND Nplex significantly prolonged the retention time in vivo and was more concentrated in the kidney. In acute gouty arthritis model rats, IND Nplex markedly relieved ankle joint swelling and mitigated synovial inflammation. In acute kidney injury model rats, IND Nplex indicated better biocompatibility and significant amelioration of renal fibrosis. Moreover, IND Nplex showed the effect of anti-inflammatory and improved renal function via determination of inflammatory factors and biochemical markers in the serum and kidney. In conclusion, these results indicate that IND Nplex exerts anti-inflammatory activity and uric acid-lowering effect and could become a promising candidate for the treatment of uric acid-related diseases.

The pathogenic mechanism of monosodium urate crystal-induced kidney injury in a rat model

Objective

(MSU) crystals usually in the kidney tubules especially collecting ducts in the medulla. Previous animal models have not fully reproduced the impact of MSU on kidneys under non-hyperuricemic conditions.

Methods

In the group treated with MSU, the upper pole of the rat kidney was injected intrarenally with 50 mg/kg of MSU, while the lower pole was injected with an equivalent volume of PBS solution. The body weight and kidney mass of the rats were observed and counted. H&E staining was used to observe the pathological damage of the kidney and to count the number of inflammatory cells. Masoon staining was used to observe the interstitial fibrosis in the kidneys of the rat model. Flow cytometric analysis was used for counting inflammatory cells in rats. ElISA was used to measure the concentration of serum and urine uric acid, creatinine and urea nitrogen in rats.

Results

At the MSU injection site, a significantly higher infiltration of inflammatory cells and a substantial increase in the area of interstitial fibrosis compared to the control group and the site of PBS injection were observed. The serum creatinine level was significantly increased in the MSU group. However, there were no significant differences in the rats' general conditions or blood inflammatory cell counts when compared to the control group.

Conclusion

The injection of urate crystals into the kidney compromised renal function, caused local pathological damage, and increased inflammatory cell infiltration and interstitial fibrosis. Intrarenal injection of MSU crystals may result in urate nephropathy. The method of intrarenal injection did not induce surgical infection or systemic inflammatory response.