Urate Transporter Research Articles

Lactobacillus paracasei 259 alleviates hyperuricemia in rats by decreasing uric acid and modulating the gut microbiota

Hyperuricemia (HUA) is a metabolic disease arising from abnormal purine metabolism. It contributes to an increased risk of kidney damage. The present study aimed to investigate the uric acid (UA)-lowering effects of Lactobacillus paracasei 259 isolated from yak yogurt and explore its underlying mechanisms. Our results revealed that L. paracasei 259 decreased the UA levels in rats and inhibited the serum activities of xanthine oxidase. In addition, L. paracasei 259 reduced the levels of pro-inflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6) in the kidney and altered the expressions of UA transporters (ABC transporter 2 (ABCG2), PDZ domain containing 1 (PDZK1), urate transporter 1 (URAT1), and sodium-phosphate cotransporter type 4 (NPT4)) to near normal levels. Moreover, it increased the abundance of beneficial bacteria in the gut and recovered the gut microbiota composition, promoting the production of short-chain fatty acids (SCFAs). These findings suggested that L. paracasei 259 can potentially be used to decrease UA levels, repair kidney damage, regulate gut microbiota, and alleviate HUA.

Phyllanthi Fructus ameliorates hyperuricemia and kidney injure via inhibiting uric acid synthesis, modulating urate transporters, and alleviating inflammation

Phyllanthi Fructus ameliorates hyperuricemia and kidney injure via inhibiting uric acid synthesis, modulating urate transporters, and alleviating inflammation

Recent Progress and Future Perspectives on Anti-Hyperuricemic Agents.

Increased biosynthesis or underexcretion of uric acid (UA or urate) in the body ultimately leads to the development of hyperuricemia. Epidemiological studies indicate that hyperuricemia is closely associated with the occurrence of various diseases such as gout and cardiovascular diseases. Currently, the first-line therapeutic medications used to reduce UA levels primarily include xanthine oxidase (XO) inhibitors, which limit UA production, and urate transporter 1 (URAT1) inhibitors, which decrease urate reabsorption and enhance urate excretion. Despite significant progress in urate-lowering therapies, long-term use of these drugs can cause hepatorenal toxicity as well as cardiovascular complications. Therefore, there is an urgent need for novel anti-hyperuricemic agents with better efficacy and lower toxicity. This perspective mainly focuses on the current research progress and design strategy of anti-hyperuricemic agents, particularly those targeting XO and URAT1. It is our hope that this perspective will provide insights into the challenges and opportunities for anti-hyperuricemic drug discovery.

The development of a novel high-throughput membrane potential assay and a solid-supported membrane (SSM)-based electrophysiological assay to study the pharmacological inhibition of GLUT9/SLC2A9 isoforms in a drug discovery program

GLUT9/SLC2A9 is a urate transporter and takes a fundamental role in the maintenance of normal serum urate levels. GLUT9 is the sole transporter of reabsorbed urate from renal epithelial cells to blood, thus making it an ideal pharmacological target for the development of urate-lowering drugs. None of the three currently available assays for studying GLUT9 pharmacological inhibition can support a high throughput drug discovery screening campaign. In this manuscript we present two novel assay technologies which can be used in a drug discovery screening cascade for GLUT9: a GLUT9 membrane potential assay for primary screening; and a solid-supported membrane (SSM)-based supported electrophysiological assay for secondary screening.

Polysaccharide isolated from Dioscorea septemloba improves hyperuricemia and alleviates renal fibrosis through gut-kidney axis in mice

Hyperuricemia (HUA) is a common metabolic disorder that often accompanies kidney diseases such as tubule damage and renal interstitial fibrosis. The preventive and therapeutic effects of Dioscorea septemloba, an anti-HUA herb, polysaccharide of which was considered as the main active ingredient on HUA, need to be explored. The major polysaccharide component, BXP, was purified from Dioscorea septemloba, with an average molecular weight of 10.432 kDa. Structural analysis inferred that BXP backbone was composed of t-β-D-Glcp-(1 → 4)-α-D-Glcp-(1 → 4)-α-D-Glcp-(1 → 4, 3)-β-D-Glcp-(1→, along with the side chain of →1)-α-D-Glcp-(6, 4 → 3, 4)-β-D-Glcp-(1→. The HUA mouse model was further established to clarify the underlying effect of BXP on HUA alleviation. As results shown, BXP decreased serum uric acid by inhibiting XOD and regulating urate transporter expression (GLUT9, OAT3, OAT1, URAT1 and ABCG2) in HUA mice, as well as relieving kidney and liver damage. Moreover, results of microbiome and metabolomics indicated that BXP improved the abundance of gut bacteria and reversed the Lipids-related metabolism disorder caused by HUA. This study indicated that BXP had potential to alleviate HUA and kidney disease through the gut-kidney axis in mice.

Ischemic stroke susceptibility associated with ALPK1 single nucleotide polymorphisms by inhibiting URAT1 in uric acid hemostasis

ObjectivesIschemic stroke (IS) prevalence rising annually, the necessity of discovering non-interventional genetic influences is progressing. Single nucleotide polymorphism (SNP) plays a pivotal role in stable inheritance of disease susceptibility. Based on the relationship between Alpha- Kinase 1 (ALPK1) and traditional IS risk factors especially hyperuricemia, our study investigated the association and function of ALPK1 SNPs with IS susceptibility. MethodsA case-control study of 1539 patients and 933 controls from northeast China was conducted. Genotyping information of ALPK1 rs2074379 and rs2074388 was collected. Four types of plasmids including rs2074379/rs2074388 G/G, A/G, G/A, and A/A were transfected into 293T cells to observe ALPK1 and SLC22A12 expression. Possible ALPK1 structures of different SNPs were predicted online. ResultsGenotype GG (OR = 1.371, CI = 1.029–1.828, P = 0.031) and GA (OR = 1.326, CI = 1.110–1.584, P = 0.002) of rs2074379 and GA of rs2074388 (OR = 1.359, CI = 1.137–1.624, P = 0.001) were found significantly susceptible to IS, with G allele on sites to be a risk allele. Rs2074379 had a multiplicative interaction with hyperuricemia (OR = 1.637, CI = 1.157–2.315, P = 0.005). Uric acid levels differed in genotypes (P < 0.001). The expression of ALPK1 (P < 0.01) and SLC22A12 in membrane urate transporter 1 (URAT1) protein (P < 0.05) functionally changed with G allele on either site. With glycine changing into aspartic acid at rs2074388, the protein secondary structure changed, but the ALPK1 protein subtype remained still. ConclusionsALPK1 rs2074379 and rs2074388 SNPs were functionally associated with IS susceptibility. The wild allele progressed IS risk probably by reducing ALPK1 expression and inhibiting URAT1 raising the uric acid level, contributing to further exploration of pathogenetic mechanisms of stroke.Chinese Clinical Trial Registration number: ChiCTR-COC-17013559.

Sleeve gastrectomy ameliorates renal injury in obesity-combined hyperuricemic nephropathy mice by modulating the AMPK/Nrf2/ABCG2 pathway

Hyperuricemic nephropathy (HN) is renal injury caused by hyperuricemia (HUA). While sleeve gastrectomy (SG) has shown promise in improving renal injury in patients with obesity-related HN, the mechanisms are not fully understood. This study induced an obesity-combined HN model in male ob/ob mice and measured serum uric acid (SUA), creatinine, and other biochemical indicators 6 weeks post-surgery. Renal histological changes were evaluated through staining techniques, and the study also assessed renal adenosine monophosphate-activated protein kinase (AMPK) and nuclear factor erythroid 2-related factor 2 (Nrf2) phosphorylation levels and urate transporter ABCG2 expression. In vitro experiments involved Nrf2 knockdown in AMPK-activated HK-2 cells and ChIP to confirm Nrf2 binding to the ABCG2 promoter. Results showed that SG reduced SUA levels, serum creatinine, and blood urea nitrogen, increased p-AMPK, p-Nrf2 protein, and ABCG2 expression, and alleviated renal fibrosis and inflammation. In vitro, Nrf2 knockdown down-regulated ABCG2 expression, and ChIP confirmed Nrf2’s role in ABCG2 transcription. The study suggests that SG may improve renal injury in HN mice by modulating the AMPK/Nrf2 pathway and upregulating ABCG2 transcription.

Molecular basis of the urate transporter URAT1 inhibition by gout drugs.

Hyperuricemia is a condition when uric acid, a waste product of purine metabolism, accumulates in the blood1. Untreated hyperuricemia can lead to crystal formation of monosodium urate in the joints, causing a painful inflammatory disease known as gout. These conditions are associated with many other diseases and affect a significant and increasing proportion of the population2-4. The human urate transporter 1 (URAT1) is responsible for the reabsorption of ~90% of uric acid in the kidneys back into the blood, making it a primary target for treating hyperuricemia and gout5. Despite decades of research and development, clinically available URAT1 inhibitors have limitations because the molecular basis of URAT1 inhibition by gout drugs remains unknown5. Here we present cryo-electron microscopy structures of URAT1 alone and in complex with three clinically relevant inhibitors: benzbromarone, lesinurad, and the novel compound TD-3. Together with functional experiments and molecular dynamics simulations, we reveal that these inhibitors bind selectively to URAT1 in inward-open states. Furthermore, we discover differences in the inhibitor dependent URAT1 conformations as well as interaction networks, which contribute to drug specificity. Our findings illuminate a general theme for URAT1 inhibition, paving the way for the design of next-generation URAT1 inhibitors in the treatment of gout and hyperuricemia.

Transport mechanism and structural pharmacology of human urate transporter URAT1

Urate is an endogenous product of purine metabolism in the liver. High urate levels in the blood lead to gout, a very common and painful inflammatory arthritis. Excreted urate is reabsorbed in the kidney mainly by URAT1 antiporter, a key target for anti-gout drugs. To uncover the mechanisms of urate transport and drug inhibition, we determined cryo-EM structures of human URAT1 with urate, counter anion pyrazinoate, or anti-gout drugs of different chemotypes — lesinurad, verinurad, and dotinurad. We captured the outward-to-inward transition of URAT1 during urate uptake, revealing that urate binds in a phenylalanine-rich pocket and engages with key gating residues to drive the transport cycle. In contrast to the single binding site for urate, pyrazinoate interacts with three distinct, functionally relevant sites within URAT1, a mechanism that has not yet been observed in other anion antiporters. In addition, we found that while all three drugs compete with substrates and halt the transport cycle, verinurad and dotinurad further hijack gating residues to achieve high potency. These insights advance our understanding of organic anion transport and provide a foundation for designing improved gout therapeutics.

The antihyperuricemic and nephroprotective effect of puerarin by reducing uric acid level and exerting anti‐inflammatory activity

AbstractHyperuricemia (HUA) is a common metabolic disease and kidney injury is one of its main complications. As a typical natural flavonoid, puerarin (PEA) has a range of pharmacological activity but the antihyperuricemic mechanism of PEA has not been reported. Herein, the inhibitory activity of PEA against xanthine oxidase (XOD) was evaluated by in vitro enzymatic reaction, and kinetic analysis, the antihyperuricemic activity, and nephroprotective effect of PEA were studied in HUA mice. The enzymatic reaction showed that the inhibitory effect of PEA (half maximal inhibitory concentration [IC50] = 4.39 µmol/L) on XOD was at the same level as allopurinol (IC50 = 4.05 µmol/L), and kinetic analysis indicated that PEA was a mixed competitive inhibitor. In vivo studies demonstrated that PEA exhibited excellent antihyperuricemic activity by inhibiting XOD and urate transporter 1 (URAT1), to reduce uric acid level. At the same time, PEA reduced the level of inflammatory cytokines and exerted significant nephroprotective effect through anti‐inflammatory activity. Molecular docking indicated that PEA closely bind to both XOD and URAT1, which had the potential to become an inhibitor of XOD and URAT1. In summary, PEA has important application value in developing novel functional food and medicine for the treatment of HUA and its complications.

Abstract P136: Phosphorylation and regulation of URAT1 by insulin and NaCl: a possible mechanism linking insulin resistance and excessive salt intake to hyperuricemia

Objective: Insulin resistance (IR) is the key environmental factor associated with hyperuricemia; however, the underlying mechanisms are not fully understood. Although several studies suggested that excessive salt intake results in hyperuricemia, the association still remains controversial. Focusing on urate transporter 1 (URAT1), we here investigated the mechanisms by which insulin and salt intake contribute to hyperuricemia. Methods: In a large UK Biobank (UKB) dataset involving 377,358 participants, we evaluated the association of TyG index (a surrogate of IR) and habitual salt intake with serum uric acid levels using multivariable regression models. We addressed whether single nucleotide polymorphisms (SNPs) that influence URAT1 expression (eQTL) modify the association of TyG index with serum uric acid levels. We also analyzed underlying mechanisms by using HEK cells expressing hURAT1. Results: In UKB dataset, TyG index and habitual salt intake were significantly and independently associated with elevated serum uric acid levels (P &lt; 0.05). From previous studies and imputation accuracy, we extracted an eQTL SNP for SLC22A12 gene and found that there is a positive interaction between TyG Index and the eQTL SNP. As post-translational modification is the key mechanism that enables adaptation to environmental changes, we evaluated the contribution of phosphorylation by AGC kinases, such as Akt, as possible downstream effectors of insulin signaling and salt-sensing pathway. Western blotting with phospho-Akt substrate motif antibody confirmed URAT1 phosphorylation and identified T350 and T408 as candidate sites. Among them, URAT1 carrying non-phosphorylatable A408 substitution (T408A-URAT1) suppressed glycosylation and plasma membrane translocation, while T350A had no effect. By using kinase screen assay involving 53 AGC and related Ser/Thr kinases, we found that SGK1, PKA, and PKG also phosphorylated URAT1-T408. Insulin and NaCl loading induced Akt and SGK1 expression respectively, which resulted in URAT1 phosphorylation and increased cell-surface membrane expression; this effect was abolished in T408A-URAT1. Finally, we found that URAT1-T408 phosphorylation was also detected in human kidney sections. Conclusion: IR and excessive salt intake contribute to hyperuricemia, and the effect is in part mediated by hURAT1. Mechanistically, insulin and NaCl promote membrane trafficking of URAT1 by inducing T408 phosphorylation through Akt and SGK1, respectively.

Salinomycin, a potent inhibitor of XOD and URAT1, ameliorates hyperuricemic nephropathy by activating NRF2, modulating the gut microbiota, and promoting SCFA production

Long-term hyperuricemia can induce kidney damage, clinically referred to as hyperuricemic nephropathy (HN), which is characterized by renal fibrosis, inflammation, and oxidative stress. However, currently used uric acid-lowering drugs are not capable of protecting the kidneys from damage. Therefore, uric acid-lowering drugs that can also protect the kidneys are urgently needed. In this study, we first discovered that salinomycin, an antibiotic, can regulate uric acid homeostasis and ameliorate kidney damage in mice with HN. Mechanistically, salinomycin inhibited serum and hepatic xanthine oxidase (XOD) activities and downregulated renal urate transporter 1 (URAT1) expression and transport activity, thus exerting uric acid-lowering effects in mice with HN. Furthermore, we found that salinomycin promoted p-NRF2 Ser40 expression, resulting in increased nuclear translocation of NRF2 and activation of NRF2. More importantly, salinomycin affected the gut microbiota and promoted the generation of short-chain fatty acids (SCFAs) in mice with HN. In conclusion, our results revealed that salinomycin maintains uric acid homeostasis and alleviates kidney injury in mice with HN by multiple mechanisms, suggesting that salinomycin might be a desirable candidate for HN treatment in the clinic.

Caffeine Inhibits Both Basal and Insulin-Activated Urate Transport.

Caffeine, an adenosine receptor antagonist, is a potent central nervous system stimulant that also impairs insulin signaling. Recent studies have suggested that coffee consumption lowers serum urate (SU) and protects against gout by unknown mechanisms. We hypothesized that caffeine lowers SU by affecting activity of urate transporters. We examined the effect of caffeine and adenosine on basal and insulin stimulation of net 14C-urate uptake in the human renal proximal tubule cell line PTC-05 and on individual urate transporters expressed in Xenopus laevis oocytes. We found that caffeine and adenosine efficiently inhibited both basal and insulin stimulation of net 14C-urate uptake mediated by endogenous urate transporters in PTC-05 cells. In oocytes expressing individual urate transporters, caffeine (>0.2 mM) more efficiently inhibited the basal urate transport activity of GLUT9 isoforms, OAT4, OAT1, OAT3, NPT1, ABCG2, and ABCC4 than did adenosine without significantly affecting URAT1 and OAT10. However, unlike adenosine, caffeine at lower concentrations (<0.2 mM) very effectively inhibited insulin activation of urate transport activity of GLUT9, OAT10, OAT1, OAT3, NPT1, ABCG2, and ABCC4 by blocking activation of Akt and extracellular signal-regulated kinase. We postulate that inhibition of urate transport activity of the re-absorptive transporters GLUT9, OAT10, and OAT4 by caffeine is a key mechanism in its urate-lowering effects. Additionally, the ability of caffeine to block insulin-activated urate transport by GLUT9a and OAT10 suggests greater relative inhibition of these transporters in hyperinsulinemia.

Verinurad Plus Allopurinol for Heart Failure With Preserved Ejection Fraction

Elevated serum uric acid (SUA) level may contribute to endothelial dysfunction; therefore, SUA is an attractive target for heart failure with preserved ejection fraction (HFpEF). However, to the authors' knowledge, no prior randomized clinical trials have evaluated SUA lowering in HFpEF. To investigate the efficacy and safety of the novel urate transporter-1 inhibitor, verinurad, in patients with HFpEF and elevated SUA level. This was a phase 2, double-blind, randomized clinical trial (32-week duration) conducted from May 2020 to April 2022. The study took place at 59 centers in 12 countries and included patients 40 years and older with HFpEF and SUA level greater than 6 mg/dL. Data were analyzed from August 2022 to May 2024. Eligible patients were randomized 1:1:1 to once-daily, oral verinurad, 12 mg, plus allopurinol, 300 mg; allopurinol, 300 mg, monotherapy; or placebo for 24 weeks after an 8-week titration period. Allopurinol was combined with verinurad to prevent verinurad-induced urate nephropathy, and the allopurinol monotherapy group was included to account for allopurinol effects in the combination therapy group. All patients received oral colchicine, 0.5 to 0.6 mg, daily for the first 12 weeks after randomization. Key end points included changes from baseline to week 32 in peak oxygen uptake (VO2), Kansas City Cardiomyopathy Questionnaire total symptom score (KCCQ-TSS), and SUA level; and safety/tolerability (including adjudicated cardiovascular events). Among 159 randomized patients (53 per treatment group; median [IQR] age, 71 [40-86] years; 103 male [65%]) with median (IQR) N-terminal pro-brain natriuretic peptide level of 527 (239-1044) pg/mL and SUA level of 7.5 (6.6-8.4) mg/dL, verinurad plus allopurinol (mean change, -59.6%; 95% CI, -64.4% to -54.2%) lowered SUA level to a greater extent than allopurinol (mean change, -37.6%; 95% CI, -45.3% to -28.9%) or placebo (mean change, 0.8%; 95% CI, -11.8% to 15.2%; P < .001). Changes in peak VO2 (verinurad plus allopurinol, 0.27 mL/kg/min; 95% CI, -0.56 to 1.10 mL/kg/min; allopurinol, -0.17 mL/kg/min; 95% CI, -1.03 to 0.69 mL/kg/min; placebo, 0.37 mL/kg/min; 95% CI, -0.45 to 1.19 mL/kg/min) and KCCQ-TSS (verinurad plus allopurinol, 4.3; 95% CI, 0.3-8.3; allopurinol, 4.5; 95% CI, 0.3-8.6; placebo, 1.2; 95% CI, -3.0 to 5.3) were similar across groups. There were no adverse safety signals. Deaths or cardiovascular events occurred in 3 patients (5.7%) in the verinurad plus allopurinol group, 8 patients (15.1%) in the allopurinol monotherapy group, and 6 patients (11.3%) in the placebo group. Results of this randomized clinical trial show that despite substantial SUA lowering, verinurad plus allopurinol did not result in a significant improvement in peak VO2 or symptoms compared with allopurinol monotherapy or placebo in HFpEF. ClinicalTrials.gov Identifier: NCT04327024.

Effect of Hepatic Impairment on the Pharmacokinetics and Pharmacodynamics of SHR4640, a Selective Human Urate Transporter 1 Inhibitor.

This parallel-group, open-label Phase I study evaluated the effect of mild to moderate hepatic impairment on pharmacokinetics (PK), pharmacodynamics (PD), and safety of a single oral dose of SHR4640. Participants with mild or moderate hepatic impairment were enrolled, with each cohort consisting of eight individuals, alongside eight well-matched controls with normal hepatic function. The participants were administered 10 mg SHR4640, and blood samples were collected for PK evaluation over 72 h. Additionally, serum uric acid (sUA) levels were measured to assess PD changes. Safety was evaluated through adverse events, laboratory tests, vital signs, and electrocardiograms. The Cmax of SHR4640 decreased by 15.0% in the mild hepatic impairment group (geometric least squares means of the ratios [GMR] = 0.850, 90% CI: 0.701-1.03) and by 17.5% in the moderate hepatic impairment group (GMR = 0.825, 90% CI: 0.681-1.00). These reductions were not statistically significant compared to the normal hepatic function group. AUC0-t and AUC0-inf were similar across all groups, indicating that overall exposure to the drug was not clinical significantly affected by hepatic impairment. Apparent clearance and volume of distribution of SHR4640 showed no association with the severity of hepatic impairment as measured by the Child-Pugh score. There were no significant differences in the changes in sUA levels from baseline across different levels of hepatic function. SHR4640 is well tolerated in participants with mild or moderate hepatic impairment. Mild and moderate hepatic impairment did not have a clinically relevant impact on PK, PD, and safety of SHR4640. SHR4640 can be used in patients with mild to moderate hepatic impairment without the need for dose adjustment.

Association of Functional Genetic Variations in Uric Acid Transporters with the Risk of Idiopathic Male Infertility: A Genetic Association Study and Bioinformatic Analysis.

Uric acid plays an important role in sustaining and improving sperm morphology, viability, and motility. It is known that SLC2A9 and ABCG2 protein are the main urate transporter and genetic variations in these genes could be associated with the levels of serum uric acid. This study aimed to investigate the association between single-nucleotide polymorphisms (SNPs) SLC2A9-rs16890979, SLC2A9-rs3733591, ABCG2-rs2231142, and ABCG2-rs2231137 with male infertility. Additionally, the correlation of these SNPs with the uric acid level in seminal plasma of infertile men was examined. Subsequently, an in silico analysis was performed. In a case-control study, 193 infertile and 154 healthy controls were recruited. After semen sample collection, the uric acid level of seminal plasma was measured by a commercial kit. After genomic DNA extraction from sperm samples, SNPs genotyping was performed by PCR-RFLP method. Lastly, the effects of SNPs on the SLC2A9 and ABCG2 gene function were evaluated by bioinformatics tools. The genetic association study revealed that there are significant associations between rs16890979, rs3733591, rs2231142, and rs2231137 genetic variations and increased risk of male infertility. Also, these variations were associated with oligozoospermia and teratozoospermia, and sometimes with asthenozoospermia. Also, we found that four studied SNPs could be associated with a decreased level of uric acid of seminal plasma in teratozoospermia and asthenozoospermia. Bioinformatic analysis revealed that the mentioned polymorphisms could affect molecular aspects of SLC2A9 and ABCG2 genes. In this preliminary study, the rs16890979, rs3733591, rs2231142, and rs2231137 genetic variations could be considered as genetic risk factors for male infertility by interfering with the uric acid level of seminal plasma.

Association of rare and common genetic variants in MOCOS with inadequate response to allopurinol.

The minor allele of the common rs2231142 ABCG2 variant predicts inadequate response to allopurinol urate lowering therapy. We hypothesize that additional variants in genes encoding urate transporters and allopurinol-to-oxypurinol metabolic enzymes also predict allopurinol response. This study included a subset of participants with gout from the Long-term Allopurinol Safety Study Evaluating Outcomes in Gout Patients, whose whole genome was sequenced (n = 563). Good responders had a 4:1 or 5:1 ratio of good (serum urate (SU) <0.36 mmol/l on allopurinol ≤300 mg/day) to poor (SU ≥ 0.36 mmol/l despite allopurinol >300 mg/day) responses over 5-6 timepoints, while inadequate responders had a 1:4 or 1:5 ratio of good to poor responses. Adherence to allopurinol was determined by pill counts, and for a subgroup (n = 303), by plasma oxypurinol >20μmol/l. Using the sequence kernel association test (SKAT) we estimated the combined effect of rare and common variants in urate secretory (ABCC4, ABCC5, ABCG2, SLC17A1, SLC17A3, SLC22A6, SLC22A8) and reuptake genes (SLC2A9, SLC22A11) and in allopurinol-to-oxypurinol metabolic genes (AOX1, MOCOS, XDH) on allopurinol response. There was an association of rare and common variants in the allopurinol-to-oxypurinol gene group (PSKAT-C = 0.019), and in MOCOS, encoding molybdenum cofactor sulphurase, with allopurinol response (PSKAT-C = 0.011). Evidence for genetic association with allopurinol response in the allopurinol-to-oxypurinol gene group (PSKAT-C = 0.002) and MOCOS (PSKAT-C < 0.001) was stronger when adherence to allopurinol therapy was confirmed by plasma oxypurinol. We provide evidence for common and rare genetic variation in MOCOS associating with allopurinol response.

Discovery of a Potent and Orally Bioavailable Xanthine Oxidase/Urate Transporter 1 Dual Inhibitor as a Potential Treatment for Hyperuricemia and Gout.

The main uric acid-lowering agents in clinical use for hyperuricemia and gout are xanthine oxidase (XO) inhibitors or urate transporter 1 (URAT1) inhibitors. While these therapies can partially control the disease, they have various limitations. The development of XO/URAT1 dual inhibitors offers the potential to enhance therapeutic potency and reduce toxicity compared with single-target inhibitors. Through scaffold hopping from the XO inhibitor febuxostat (2) and the URAT1 inhibitor probenecid (3), followed by structure-activity relationship (SAR) studies, we identified compound 27 as a potent dual inhibitor of XO and URAT1. Compound 27 demonstrated significant dual inhibition in vitro (XO IC50 = 35 nM; URAT1 IC50 = 31 nM) and exhibited favorable pharmacology and pharmacokinetic (PK) profiles in multiple species including monkeys. Furthermore, toxicity studies in rats and monkeys revealed general safety profiles, supporting that compound 27 emerges as a promising novel drug candidate with potent XO/URAT1 dual inhibition for the treatment of gout.

The pathogenesis of gout: molecular insights from genetic, epigenomic and transcriptomic studies.

The pathogenesis of gout involves a series of steps beginning with hyperuricaemia, followed by the deposition ofmonosodium urate crystal in articular structures and culminating in an innate immune response, mediated by the NLRP3 inflammasome, to the deposited crystals. Large genome-wide association studies (GWAS) of serum urate levels initially identified the genetic variants with thestrongest effects, mapping mainlyto genes that encode urate transporters in the kidney and gut. Other GWAS highlighted the importance of uncommon genetic variants. More recently, genetic and epigenetic genome-wide studies have revealed new pathways in the inflammatory process of gout, including genetic associations with epigenomic modifiers. Epigenome-wide association studies are also implicating epigenomic remodelling in gout, which perhaps regulates the responsiveness of the innate immune system to monosodium urate crystals. Notably, genes implicated in gout GWAS do not include those encodingcomponents of the NLRP3 inflammasome itself, but instead include genes encoding moleculesinvolved in its regulation. Knowledge of the molecular mechanisms underlying gout has advanced through the translation of genetic associations into specific molecular mechanisms. Notable examples include ABCG2, HNF4A, PDZK1, MAF and IL37. Current genetic studies are dominated by participants of European ancestry; however, studies focusing on other population groups are discovering informative population-specific variants associated with gout.

Ilex cornuta leaves extracts ameliorate hyperuricemia by modulating uric acid transporters

Ethnopharmacological relevanceIlex cornuta is a valuable species of the Holly genus (Aquifoliaceae), and mainly distributed in eastern China. It is not only made into tea, namely Kudingcha, but also used as traditional medicine to relieve cough, headache, gout, and nourish liver and kidney. Aim of the studyThe purpose of this study was to explore the exact efficacy of different extracts from Ilex cornuta in the treatment of hyperuricemia in vitro and in vivo, and to explore its pharmacological mechanism, so as to bring new ideas for the development of new drugs for reducing uric acid (UA) and anti-gout. Materials and methodsFive crude extracts from Ilex cornuta leaves were extracted by different methods. Then, the xanthine oxidase inhibitory activity and antioxidant capacity of 5 extracts in vitro were compared to screen the extract with the most UA regulating potential. In vivo experiment, hyperuricemia model of mice was established by intragastric administration of potassium oxonate and feeding high yeast diet. Biochemical indexes such as serum UA level, xanthine oxidase activity, liver and kidney index of mice in each group were detected. The pathological sections of kidney and liver tissues were also observed and compared. The mechanism of Ilex cornuta leaves (western blotting, and RT-qPCR) in the treatment of hyperuricemia was further explored by targeting UA transporters ABCG2, GLUT9, and URAT1. ResultsThe in vitro results of inhibitory activity of xanthine oxidase showed that the crude saponin extract was the best, followed by crude flavonoids extract. Then, the in vivo results reflected that both crude saponins and crude flavonoids extracts could significantly reduce the serum UA level, inhibit the activity of xanthine oxidase in serum and liver, and maintain serum urea nitrogen and creatinine at normal level. Meanwhile, there was no liver and kidney injury in mice. Through the comparison of the mechanism results, it was found that both extracts could up-regulate the expression of ABCG2 protein and mRNA related to UA excretion, and down-regulate the expression of GLUT9 and URAT1 protein and mRNA. ConclusionThe crude flavonoids and saponins of Ilex cornuta leaves not only inhibited XOD activity in vitro, but also significantly controlled XOD activity and reduced UA level in hyperuricemia mice in vivo. One of the potential mechanisms was to regulate UA level in vivo by regulating ABCG2, GLUT9, and URAT1 transporters directly related to UA transport, thus achieving the effect of intervening hyperuricemia. This study provided a preliminary experimental basis for the development of new drugs of Ilex cornuta leaves for treating hyperuricemia.