Uric Acid Has Direct Proinflammatory Effects on Human Macrophages by Increasing Proinflammatory Mediators and Bacterial Phagocytosis Probably via URAT1

Sweet regulation - The emerging immunoregulatory roles of hexoses

BACKGROUND

It is widely acknowledged that dietary habits have profound impacts on human health and diseases. As the most important sweeteners and energy sources in human diets, hexoses take part in a broad range of physiopathological processes. In recent years, emerging evidence has uncovered the crucial roles of hexoses, such as glucose, fructose, mannose, and galactose, in controlling the differentiation or function of immune cells.

AIM OF REVIEW

Herein, we reviewed the latest research progresses in the hexose-mediated modulation of immune responses, provided in-depth analyses of the underlying mechanisms, and discussed the unresolved issues in this field.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Owing to their immunoregulatory effects, hexoses affect the onset and progression of various types of immune disorders, including inflammatory diseases, autoimmune diseases, and tumor immune evasion. Thus, targeting hexose metabolism is becoming a promising strategy for reversing immune abnormalities in diseases.

Zerumbone reduces TLR2 stimulation-induced M1 macrophage polarization pattern via upregulation of Nrf-2 expression in murine macrophages

Hyperuricemia contributes significantly to gout arthritis pathogenesis, which promotes urate crystal deposition in the joints and activates joint-resident macrophages and circulating monocytes to initiate a state of inflammatory arthritis. In the joint, macrophages have an immune defense role where the presence of urate crystals results in the inflammatory mediators secretion, inflammatory cells recruitment to the joint, and shift macrophage population toward M1 pro-inflammatory phenotypes. Current treatment modalities of gout arthritis have side effects that limit their use in the elderly. A novel treatment that targets macrophage polarization to re-establish homeostasis may initiate a drug discovery program of novel disease-modifying agents for gout. Zerumbone (Zer) is a sesquiterpenoid bioactive compound found in the rhizome of Zingiberaceae family and possesses anti-inflammatory, antioxidant, and anti-proliferative activity. Our study hypothesized that soluble uric acid (sUA) and Pam3CSK4 (TLR2 agonist) reduce the anti-inflammatory function of murine M2 bone marrow-derived macrophages and change the expression of M2 genetic markers toward M1 phenotypes. We observed that priming of M2 macrophages with sUA and Pam3CSK4 significantly decreased M2 specific markers expression, e.g., Arg-1, Ym-1, and Fizz-1, enhanced mRNA expression of IL-1β, TNF-α, CXCL2, and iNOS and increased oxidative stress in M2 macrophages, as exhibited by a reduction in Nrf2 expression. We also aimed to study the impact of Zer on reducing the pro-inflammatory effect of sUA in TLR2-stimulated M2 macrophages. We noticed that Zer treatment significantly reduced L-1β and TNF-α production following Pam3CSK4 + sUA treatment on M2 macrophages. Furthermore, Zer reduced the caspase-1 activity without altering cytosolic NLRP3 content in challenged M2 BMDMs. We also observed that Zer significantly enhanced M2-associated marker's expression, e.g., Arg-1, Ym-1, and Fizz-1, and augmented Nrf-2 and other antioxidant proteins, including HMOX1 and srxn1expression following Pam3CSK4 + sUA treatment. We draw the conclusion that Zer is a potentially effective anti-inflammatory treatment for gout arthritis linked to hyperuricemia.

Fructose regulates the pentose phosphate pathway and induces an inflammatory and resolution phenotype in Kupffer cells

Over-consumption of fructose in adults and children has been linked to increased risk of non-alcoholic fatty liver disease (NAFLD). Recent studies have highlighted the effect of fructose on liver inflammation, fibrosis, and immune cell activation. However, little work summarizes the direct impact of fructose on macrophage infiltration, phenotype, and function within the liver. We demonstrate that chronic fructose diet decreased Kupffer cell populations while increasing transitioning monocytes. In addition, fructose increased fibrotic gene expression of collagen 1 alpha 1 (Col1a1) and tissue metallopeptidase inhibitor 1 (Timp1) as well as inflammatory gene expression of tumor necrosis factor alpha (Tnfa) and expression of transmembrane glycoprotein NMB (Gpnmb) in liver tissue compared to glucose and control diets. Single cell RNA sequencing (scRNAseq) revealed fructose elevated expression of matrix metallopeptidase 12 (Mmp12), interleukin 1 receptor antagonist (Il1rn), and radical S-adenosyl methionine domain (Rsad2) in liver and hepatic macrophages. In vitro studies using IMKC and J774.1 cells demonstrated decreased viability when exposed to fructose. Additionally, fructose increased Gpnmb, Tnfa, Mmp12, Il1rn, and Rsad2 in unpolarized IMKC. By mass spectrometry, C13 fructose tracing detected fructose metabolites in glycolysis and the pentose phosphate pathway (PPP). Inhibition of the PPP further increased fructose induced Il6, Gpnmb, Mmp12, Il1rn, and Rsad2 in nonpolarized IMKC. Taken together, fructose decreases cell viability while upregulating resolution and anti-inflammatory associated genes in Kupffer cells.

Serum uric acid levels in kidney transplant recipients: A cause for concern? A review of recent literature

The impact of elevated serum uric acid levels i.e., hyperuricemia, on native and transplant chronic kidney disease progression has been debated. This literature review presents an analysis of multiple studies exploring the relationship between serum uric acid levels and kidney transplant outcomes. The review includes a summary of the pathophysiology of hyperuricemia and gout, a review of urate-lowering therapies, and an appraisal of multiple studies examining the association or lack thereof between serum uric acid level and kidney transplant outcomes. Based on these studies, elevated serum uric acid levels may contribute to CKD progression in kidney transplant recipients. In this review, we also summarize current literature to highlight risk factors associated with hyperuricemia as well as the need for further investigation to monitor and manage hyperuricemia in kidney transplant recipients.

Uric acid en route to gout

Gout and hyperuricemia (HU) have generated immense attention due to increased prevalence. Gout is a multifactorial metabolic and inflammatory disease that occurs when increased uric acid (UA) induce HU resulting in monosodium urate (MSU) crystal deposition in joints. However, gout pathogenesis does not always involve these events and HU does not always cause a gout flare. Treatment with UA-lowering therapeutics may not prevent or reduce the incidence of gout flare or gout-associated comorbidities. UA exhibits both pro- and anti-inflammation functions in gout pathogenesis. HU and gout share mechanistic and metabolic connections at a systematic level, as shown by studies on associated comorbidities. Recent studies on the interplay between UA, HU, MSU and gout as well as the development of HU and gout in association with metabolic syndromes, non-alcoholic fatty liver disease (NAFLD), and cardiovascular, renal and cerebrovascular diseases are discussed. This review examines current and potential therapeutic regimens and illuminates the journey from disrupted UA to gout.

Wuling San Based on Network Pharmacology and in vivo Evidence Against Hyperuricemia via Improving Oxidative Stress and Inhibiting Inflammation

Background

Hyperuricemia (HUA) is a major public health issue with a high prevalence worldwide. Wuling San (WLS) is an effective treatment for HUA. However, the active compounds and the related mechanism are unclear. In this study, we aimed to explore the active compounds and the underlying pharmacological mechanisms of WLS against HUA.

Methods

First, a network pharmacology approach was used to detect active compounds of WLS, and potential targets and signaling pathways involved in the treatment of HUA were predicted. Then, a molecular docking strategy was used to predict the affinity between active compounds and key targets. Finally, to verify the prediction, the HUA rat model was established.

Results

49 active compounds with 108 common targets were obtained. Besides, cerevisterol, luteolin, ergosterol peroxide, beta-sitosterol, and sitosterol were identified as key active compounds. In PPI analysis, TNF, IL6, CASP3, PPARG, STAT3, and other 12 core targets were obtained. GO enrichment analysis indicated that WLS was likely to interfere with oxidative stress in the treatment of HUA, and KEGG enrichment analysis indicated multiple inflammation-related signaling pathways possibly involved in the treatment of HUA by WLS, including TNF, and NOD-like receptor, HIF-1, PI3K-Akt, and IL-17 signaling pathways. The results of molecular docking indicated that the active compounds had good binding properties to their key targets. In the validation experiments, WLS significantly reduced the levels of serum uric acid (SUA) and serum malondialdehyde (MDA). Moreover, WLS not only significantly increased the levels of total antioxidant capacity (T-AOC) and superoxide dismutase (SOD), but also inhibited the expression of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6).

Conclusion

In the present study, we demonstrate that WLS has multicomponent, multitarget, and multi-pathway properties in the treatment of HUA. Its potential capability to reduce SUA could be ascribed to oxidative stress improvement and inflammation inhibition.

Uric acid effects on glutathione metabolism estimated by induction of glutamate-cysteine ligase, glutathione reductase and glutathione synthetase in mouse J744A.1 macrophage cell line

INTRODUCTION

Elevated plasma levels of uric acid (UA) are considered an independent risk factor for hypertension, diabetes, cardiovascular disease, endothelial and vascular damage, obesity, and metabolic syndrome. Even physiological concentrations of soluble UA have been proved to induce gene expression of macrophage-secreted inflammatory cytokines and stimulate production of reactive oxygen species in mature adipocytes. UA is also described as a powerful endogenous plasma antioxidant, which reveals a paradox of duality for this parameter.

Construction and Evaluation of a Novel Organic Anion Transporter 1/3 CRISPR/Cas9 Double-Knockout Rat Model

BACKGROUND

Organic anion transporter 1 (OAT1) and OAT3 have an overlapping spectrum of substrates such that one can exert a compensatory effect when the other is dysfunctional. As a result, the knockout of either OAT1 or OAT3 is not reflected in a change in the excretion of organic anionic substrates. To date, only the mOAT1 and mOAT3 individual knockout mouse models have been available.

METHODS

In this study, we successfully generated a Slc22a6/Slc22a8 double-knockout (KO) rat model using CRISPR/Cas9 technology and evaluated its biological properties.

RESULTS

The double-knockout rat model did not expression mRNA for rOAT1 or rOAT3 in the kidneys. Consistently, the renal excretion of p-aminohippuric acid (PAH), the classical substrate of OAT1/OAT3, was substantially decreased in the Slc22a6/Slc22a8 double-knockout rats. The relative mRNA level of Slco4c1 was up-regulated in KO rats. No renal pathological phenotype was evident. The renal elimination of the organic anionic drug furosemide was nearly abolished in the Slc22a6/Slc22a8 knockout rats, but elimination of the organic cationic drug metformin was hardly affected.

CONCLUSIONS

These results demonstrate that this rat model is a useful tool for investigating the functions of OAT1/OAT3 in metabolic diseases, drug metabolism and pharmacokinetics, and OATs-mediated drug interactions.

Asymptomatic Hyperuricemia Promotes Recovery from Ischemic Organ Injury by Modulating the Phenotype of Macrophages

Acute organ injury, such as acute kidney injury (AKI) and disease (AKD), are major causes of morbidity and mortality worldwide. Hyperuricemia (HU) is common in patients with impaired kidney function but the impact of asymptomatic HU on the different phases of AKI/AKD is incompletely understood. We hypothesized that asymptomatic HU would attenuate AKD because soluble, in contrast to crystalline, uric acid (sUA) can attenuate sterile inflammation. In vitro, 10 mg/dL sUA decreased reactive oxygen species and interleukin-6 production in macrophages, while enhancing fatty acid oxidation as compared with a physiological concentration of 5 mg/dL sUA or medium. In transgenic mice, asymptomatic HU of 7–10 mg/dL did not affect post-ischemic AKI/AKD but accelerated the recovery of kidney excretory function on day 14. Improved functional outcome was associated with better tubular integrity, less peritubular inflammation, and interstitial fibrosis. Mechanistic studies suggested that HU shifted macrophage polarization towards an anti-inflammatory M2-like phenotype characterized by expression of anti-oxidative and metabolic genes as compared with post-ischemic AKI-chronic kidney disease transition in mice without HU. Our data imply that asymptomatic HU acts as anti-oxidant on macrophages and tubular epithelial cells, which endorses the recovery of kidney function and structure upon AKI.

URAT1-selective inhibition ameliorates insulin resistance by attenuating diet-induced hepatic steatosis and brown adipose tissue whitening in mice

Objective

Accumulating evidence indicates that high uric acid (UA) is strongly associated with obesity and metabolic syndrome and drives the development of nonalcoholic fatty liver disease (NAFLD) and insulin resistance. Although urate transporter-1 (URAT1), which is primarily expressed in the kidneys, plays a critical role in the development of hyperuricemia, its pathophysiological implication in NAFLD and insulin resistance remains unclear. We herein investigated the role and functional significance of URAT1 in diet-induced obese mice.

Methods

Mice fed a high-fat diet (HFD) for 16–18 weeks or a normal-fat diet (NFD) were treated with or without a novel oral URAT1-selective inhibitor (dotinurad [50 mg/kg/day]) for another 4 weeks.

Results

We found that URAT1 was also expressed in the liver and brown adipose tissue (BAT) other than the kidneys. Dotinurad administration significantly ameliorated HFD-induced obesity and insulin resistance. HFD markedly induced NAFLD, which was characterized by severe hepatic steatosis as well as the elevation of serum ALT activity and tissue inflammatory cytokine genes (chemokine ligand 2 (Ccl2) and tissue necrosis factor α (TNFα)), all of which were attenuated by dotinurad. Similarly, HFD significantly increased URAT1 expression in BAT, resulting in lipid accumulation (whitening of BAT), and increased the production of tissue reactive oxygen species (ROS), which were reduced by dotinurad via UCP1 activation.

Conclusions

In conclusion, a novel URAT1-selective inhibitor, dotinurad, ameliorates insulin resistance by attenuating hepatic steatosis and promoting rebrowning of lipid-rich BAT in HFD-induced obese mice. URAT1 serves as a key regulator of the pathophysiology of metabolic syndrome and may be a new therapeutic target for insulin-resistant individuals, particularly those with concomitant NAFLD.

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URAT1 is expressed in the liver and brown adipose tissue other than in the kidneys.

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URAT1-selective inhibitor ameliorates HFD-induced insulin resistance.

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URAT1-selective inhibitor improves NAFLD through the inhibition of Ccl2 and TNFα.

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URAT1-selective inhibitor promotes rebrowning of HFD-induced lipid-rich BAT.

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URAT1 serves as a key regulator of the pathophysiology of metabolic syndrome.

Role of Damage-Associated Molecular Pattern/Cell Death Pathways in Vaccine-Induced Immunity

Immune responses induced by natural infection and vaccination are known to be initiated by the recognition of microbial patterns by cognate receptors, since microbes and most vaccine components contain pathogen-associated molecular patterns. Recent discoveries on the roles of damage-associated molecular patterns (DAMPs) and cell death in immunogenicity have improved our understanding of the mechanism underlying vaccine-induced immunity. DAMPs are usually immunologically inert, but can transform into alarming signals to activate the resting immune system in response to pathogenic infection, cellular stress and death, or tissue damage. The activation of DAMPs and cell death pathways can trigger local inflammation, occasionally mediating adaptive immunity, including antibody- and cell-mediated immune responses. Emerging evidence indicates that the components of vaccines and adjuvants induce immunogenicity via the stimulation of DAMP/cell death pathways. Furthermore, strategies for targeting this pathway to enhance immunogenicity are being investigated actively. In this review, we describe various DAMPs and focus on the roles of DAMP/cell death pathways in the context of vaccines for infectious diseases and cancer.

Cardiovascular risk associated with allopurinol vs. benzbromarone in patients with gout

Aims 

With the high prevalence of gout and associated cardiovascular (CV) diseases, information on the comparative CV safety of individual urate-lowering drugs becomes increasingly important. However, few studies examined the CV risk of uricosuric agents. We compared CV risk among patients with gout who initiated allopurinol vs. benzbromarone.

Methods and results 

Using the Korean National Health Insurance claims data (2002–17), we conducted a cohort study of 124 434 gout patients who initiated either allopurinol (n = 103 695) or benzbromarone (n = 20 739), matched on propensity score at a 5:1 ratio. The primary outcome was a composite CV endpoint of myocardial infarction, stroke/transient ischaemic attack, or coronary revascularization. To account for competing risk of death, we used cause-specific hazard models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the outcomes comparing allopurinol initiators with benzbromarone. Over a mean follow-up of 1.16 years, 2258 patients developed a composite CV event. The incidence rate of the composite CV event was higher in allopurinol initiators (1.81 per 100 person-years) than benzbromarone (1.61 per 100 person-years) with a HR of 1.22 (95% CI 1.05–1.41). The HR for all-cause mortality was 1.66 (95% CI 1.43–1.93) among allopurinol initiators compared with benzbromarone.

Conclusion 

In this large population-based cohort of gout patients, allopurinol was associated with an increased risk of composite CV events and all-cause mortality compared to benzbromarone. Benzbromarone may reduce CV risk and mortality in patients with gout, although more studies are necessary to confirm our findings and to advance our understanding of the underlying mechanisms.

Crocetin attenuating Urinary tract Infection and adherence of uropathogenic E. coli in NRK-52E cells via an inflammatory pathway

BACKGROUND AND OBJECTIVE

Urinary tract infections (UTI) are commonly treated with broad-spectrum antibiotics, but treatment has limitation due to causes of nephrotoxicity in uroepithelial cells. Recently, the researcher focuses their research on alternative therapy for the treatment of UTI. This study evaluated the anti-infectious effect of crocetin against adherence of pathogenic [2-¹⁴ C]-acetate labeled Escherichia coli (MTCC-729) to rat proximal renal tubular cells (NRK-52E cells) and explores the possible mechanism of action.

MATERIALS AND METHODS

In vitro cytotoxicity and radio acetate labeled tests were performed on NRK-52E cells. The rats were divided into five different groups as follows: normal control (NC), disease control (DC), and various doses of crocetin (1.25, 2.5, and 5 mg/kg) treated group rats. White blood cells in blood, urine, and bacterial colony counts were estimated at regular intervals. Pro-inflammatory cytokines, such as interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), interleukin-10 (IL-10), and interleukin-8 (IL-8), were also estimated. In the current study, we estimated the mRNA expression of toll-like receptor-4 (TLR-4) and toll-like receptor-2 (TLR-2) in the renal and bladder tissues.

RESULTS

Crocetin significantly (p < .05) inhibited the adherence of E. Coli in NRK-52E cells. Crocetin suppresses the lipid peroxidation (LPO) 42% in cells treated with H₂ O₂ cells without crocetin. The white blood cells (WBC) count in blood and urine were augmented and crocetin treatment significantly (p < .05) reduced the WBC in urine and blood. The pro-inflammatory cytokines, such as IL-6, MCP-1, IL-10, and IL-8, significantly (p < .05) increased in the DC group and crocetin significantly (p < .05) reduced the pro-inflammatory cytokines. Dose-dependent treatment of crocetin significantly reduced the mRNA expression of TLR2 and TLR4 in the renal and bladder tissues.

CONCLUSION

Crocetin considerably reduced the bacterial adherence to NRK-52E cells, attenuated the H₂ O₂ induced toxicity in NRK-52E cells and also improved the renal tubular function, and reduced the inflammatory response via altering the inflammatory and antioxidant markers.

PRACTICAL APPLICATION

As we all know that urinary tract infection is the most common disease worldwide. In this study, we scrutinized the protective effect of crocetin against urinary tract infection. Crocetin treatment considerably reduced the zone of inhibition and improved radioactivity. Crocetin significantly reduced the levels of cytokines and inflammatory mediators. Crocetin can be used as a protective drug in the treatment of urinary tract infections.

The Adipokine Component in the Molecular Regulation of Cancer Cell Survival, Proliferation and Metastasis

A hormonal imbalance may disrupt the rigorously monitored cellular microenvironment by hampering the natural homeostatic mechanisms. The most common example of such hormonal glitch could be seen in obesity where the uprise in adipokine levels is in virtue of the expanding bulk of adipose tissue. Such aberrant endocrine signaling disrupts the regulation of cellular fate, rendering the cells to live in a tumor supportive microenvironment. Previously, it was believed that the adipokines support cancer proliferation and metastasis with no direct involvement in neoplastic transformations and tumorigenesis. However, the recent studies have reported discrete mechanisms that establish the direct involvement of adipokine signaling in tumorigenesis. Moreover, the individual adipokine profile of the patients has never been considered in the prognosis and staging of the disease. Hence, the present manuscript has focused on the reported extensive mechanisms that culminate the basis of poor prognosis and diminished survival rate in obese cancer patients.

[Exploring the therapeutic mechanism of Simiao pills for hyperuricemia based on network pharmacology and molecular docking]

OBJECTIVE

To explore the mechanism of Simiao pills for treatment of hyperuricemia based on network pharmacology and molecular docking.

OBJECTIVE

The active ingredients of Simiao pills and their targets of action were predicted using TCMSP, SEA, Swiss and PharmMapper databases. GeneCards and TCD databases were searched for the disease targets related to hyperuricemia. Cytoscape 3.6.1 was used to construct a protein-protein interaction network. GO enrichment analysis and KEGG pathway analysis were carried out on the STRING platform. The binding between the main compounds and the key targets were predicted using the SwissDock platform for molecular docking.

OBJECTIVE

We identified 28 active ingredients and 429 potential targets in Simiao pills, 494 disease targets related to hyperuricemia, and 118 common targets between Simiao pills and hyperuricemia. Several key targets including AKT1, IL- 6, JUN, TNF and CASP3 were screened for molecular docking, which had good binding activities with berberrubine, epiberberine, stigmasterol and sitosterol. AKT1, IL-6, JUN, TNF and CASP3 were predicted to be the key targets for Simiao pills for treating hyperuricemia. KEGG pathway enrichment analysis showed that Simiao pills produced therapeutic effects on hyperuricemia through multiple signaling pathways including the TNF signaling pathway, apoptosis signaling pathway and IL-17 signaling pathway.

OBJECTIVE

Simiao pills produces therapeutic effects on hyperuricemia through multiple components and targets and the synergy of several pathways. Our finding provides a theoretical basis for further study of the active ingredients and therapeutic mechanism of Simiao pills for treating hyperuricemia.

Why Does Hyperuricemia Not Necessarily Induce Gout?

Hyperuricemia is a risk factor for gout. It has been well observed that a large proportion of individuals with hyperuricemia have never had a gout flare(s), while some patients with gout can have a normuricemia. This raises a puzzle of the real role of serum uric acid (SUA) in the occurrence of gout flares. As the molecule of uric acid has its dual effects in vivo with antioxidant properties as well as being an inflammatory promoter, it has been placed in a delicate position in balancing metabolisms. Gout seems to be a multifactorial metabolic disease and its pathogenesis should not rely solely on hyperuricemia or monosodium urate (MSU) crystals. This critical review aims to unfold the mechanisms of the SUA role participating in gout development. It also discusses some key elements which are prerequisites for the formation of gout in association with the current therapeutic regime. The compilation should be helpful in precisely fighting for a cure of gout clinically and pharmaceutically.

Usefulness of Extra Virgin Olive Oil Minor Polar Compounds in the Management of Chronic Kidney Disease Patients

Chronic kidney disease (CKD) is one of the most common chronic non-communicable degenerative diseases and it represents an important risk factor for cardiovascular morbidity and mortality. The Mediterranean diet, in which extra virgin olive oil (EVOO) is the main source of vegetal fats, represents a nutritional-diet regimen that is useful for the treatment of CKD and its comorbidities. We tested two different EVOOs, characterized by a high (Synergy) and medium (Luxolio) content of minor polar compounds (MPCs), detected by HPLC-DAD-MS analysis, in 40 nephropathic patients, at a dose of 40 mL/day for 9 weeks. We evaluated the effects of these two EVOOs on renal function, body composition, oxidative stress, and inflammatory state, after 9 weeks of EVOOs consumption (T1) and after 2 months of wash-out (T2). We observed an improvement of renal function biomarkers (estimated-glomerular filtration rate, albuminuria, azotemia, uric acid), lipid profile, oxidative stress, inflammatory parameters (erythrocyte sedimentation rate, C-reactive protein) and in body composition at T1. These healthy effects were greater and persisted over time after the wash-out period in Synergy patients. The high MPC EVOO content seems to exert an antioxidant and anti-inflammatory effect in nephropathic patients and these protective actions are maintained over time.

Metformin alleviates hyperuricaemia-induced serum FFA elevation and insulin resistance by inhibiting adipocyte hypertrophy and reversing suppressed white adipose tissue beiging

Hyperuricaemia (HUA) significantly increases the risk of metabolic syndrome and is strongly associated with the increased prevalence of high serum free fatty acids (FFAs) and insulin resistance. However, the underlying mechanisms are not well established, especially the effect of uric acid (UA) on adipose tissue, a vital organ in regulating whole-body energy and FFA homeostasis. In the present study, we noticed that adipocytes from the white adipose tissue of patients with HUA were hypertrophied and had decreased UCP1 expression. To test the effects of UA on adipose tissue, we built both in vitro and in vivo HUA models and elucidated that a high level of UA could induce hypertrophy of adipocytes, inhibit their hyperplasia and reduce their beige-like characteristics. According to mRNA-sequencing analysis, UA significantly decreased the expression of leptin in adipocytes, which was closely related to fatty acid metabolism and the AMPK signalling pathway, as indicated by KEGG pathway analysis. Moreover, lowering UA using benzbromarone (a uricosuric agent) or metformin-induced activation of AMPK expression significantly attenuated UA-induced FFA metabolism impairment and adipose beiging suppression, which subsequently alleviated serum FFA elevation and insulin resistance in HUA mice. Taken together, these observations confirm that UA is involved in the aetiology of metabolic abnormalities in adipose tissue by regulating leptin-AMPK pathway, and metformin could lessen HUA-induced serum FFA elevation and insulin resistance by improving adipose tissue function via AMPK activation. Therefore, metformin could represent a novel treatment strategy for HUA-related metabolic disorders.