A Mendelian randomization study of serum uric acid with the risk of venous thromboembolism.

BACKGROUND: Observational studies have linked hyperuricemia with venous thromboembolism (VTE). We aimed to investigate whether there are causal relationships between uric acid levels and VTE and its subtypes, including deep venous thrombosis (DVT) of the lower extremities and pulmonary embolism (PE). METHODS: We utilized Mendelian randomization (MR) analysis to estimate the causal association in European individuals. We extracted two sets of polygenic instruments strongly associated (p < 5 × 10-8) with uric acid from the CKDGen consortium and UK biobank, respectively. Genetic associations with the risk of VTE, DVT, and PE were obtained from the FinnGen biobank. We used the inverse-variance weighted method as the preliminary estimate. Additionally, we employed MR-Egger, weighted median, and Mendelian randomization pleiotropy residual sum and outlier method as complementary assessments. Sensitivity analyses were performed to test for pleiotropic bias. RESULTS: The genetically instrumented serum uric acid levels had no causal effects on VTE, DVT, and PE. Two sets of polygenic instruments used for exposure, along with three complementary MR methods, also yielded no significant association. CONCLUSIONS: Our MR analysis provided no compelling evidence for a causal relationship of serum uric acid with the risk of VTE. This suggests that uric acid-lowering therapies in patients with hyperuricemia may not be effective in reducing the likelihood of developing VTE.

The Nephroprotective Effects of Hibiscus sabdariffa Leaf and Ellagic Acid in Vitro and in Vivo Models of Hyperuricemic Nephropathy.

Hyperuricemic nephropathy (HN) is caused by urate crystals that get deposited in the kidney and contribute to renal fibrosis. Uric acid (UA) has been proven to directly cause renal mesangial cell oxidative stress and fibrosis in the pathogenesis of HN. Some antioxidants can be used as chemopreventive agents of HN. Hibiscus sabdariffa leaf extracts (HLE), rich in polyphenol, have been shown to possess hypoglycemic, antioxidant, hypolipidemic, antiatherosclerotic, and anticancer effects. The aim of the study is to examine the inhibitory effect of HLE and its main component ellagic acid (EA) on renal fibrosis. In vitro, mouse renal glomerular mesangial SV40MES13 cells pretreated with UA were demonstrated to trigger obvious morphological changes and viability loss, as well as affect matrix metalloproteinases (MMPs) activities. Noncytotoxic doses of HLE and EA abolished the UA-induced cell injury and MMP-2/9 secretion. In addition, HLE and EA exhibited antioxidant and anti-inflammatory effects on the UA-treated cells with a reduction in transforming growth factor-beta (TGF-ß) production. Next, the UA-activated pro-fibrotic factors, extracellular matrix (ECM) deposition, and epithelial-mesenchymal-transition (EMT) were inhibited by HLE or EA. Mechanistic assays indicated that antifibrotic effects of HLE might be mediated via TGF-ß/Smad signaling, as confirmed by the transfection of Smad7 siRNA. In vivo, HLE and EA supplementations significantly alleviated HN development, which may result from inhibiting adenine-induced TGF-ß production accompanying oxidative stress and inflammation, as well as fibrogenesis. Our data imply that EA-enriched HLE regulates the TGF-ß/Smad signaling, which in turn led to reduced renal mesangial cell injury and fibrosis in HN and provided a new mechanism for its nephroprotective activity.

Multi-omics analysis reveals therapeutic effects of Bacillus subtilis-fermented Astragalus membranaceus in hyperuricemia via modulation of gut microbiota.

At present, uncovering how to preventandcontrol hyperuricemia has become an important public health issue. Fermented traditionalChinesemedicine has exhibited promising applications in the clinical management of hyperuricemia. In this study, we generated a hyperuricemic mouse model to explore the potent therapeutic ability of Bacillus subtilis-fermented Astragalus membranaceus (BFA) on this condition by multi-omics analysis. We found that the serum uric acid level was decreased in hyperuricemic mice after BFA treatment. BFA effectively attenuated renal inflammation and regulated the expression of urate transporters. Additionally, we found that BFA could increase the abundances of butyrate-producing bacteria, including Butyricimonas synergistica, Odoribacter splanchnicus, and Collinsella tanakaei, and probiotics, including Lactobacillus intestinalis and Bacillus mycoides, in hyperuricemic mice. Therefore, we believe that BFA has the potential to become a novel safe and valid functional food for addressing hyperuricemia.

Berberine Attenuates Hyperuricemia by Regulating Urate Transporters and Gut Microbiota.

Hyperuricemia (HUA) and its associated metabolic diseases seriously threaten human health, and commensal microbiota has been identified as one of the environmental triggers of HUA. The role of berberine (BBR) in the treatment of HUA has begun to receive attention in recent years. However, how BBR modulates the microbiota to slow HUA progression is unclear. In this study, we showed that BBR alleviated potassium oxonate (PO)-induced HUA in mice by suppressing the expression of xanthine oxidase (XOD) in the liver and urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) in the kidney. The BBR also improved renal inflammation by inhibiting the expression of TNF-[Formula: see text], IL-1[Formula: see text], and caspase-1. Subsequently, we evaluated whether the observed anti-HUA effects of BBR were associated with changes in gut microbial structure in mice. 16S rRNA sequencing data showed that BBR significantly altered the community compositional structure of the gut microbiota. Specifically, BBR enriched the abundance of Coprococcus, Bacteroides, Akkermansia, and Prevotella. Antibiotic treatment can reverse the anti-HUA effects of BBR that further supports the role of the gut microbiota. In conclusion, our study provides evidence that BBR ameliorates PO-induced HUA by modulating the gut microbiota.

[Effect of granules made by new-medicinal parts of Crocus sativus on hyperuricemia in rats and its mechanism].

To explore the effect of the granules made by new-medicinal parts of Crocus sativus(NMPCS) on hyperuricemia(HUA) in rats, the rat model of HUA was established by intramuscular injection of 3% potassium oxonate and intraperitoneal injection of 4% pyrazinamide. The content of serum uric acid was monitored every week for 3 consecutive weeks. After the experiment, the levels of serum uric acid, urine uric acid, serum creatinine, blood urea nitrogen(BUN), and xanthine oxidase(XOD) were determined. The protein and gene expressions of XOD were determined by Western blot method and fluorescence quantitative polymerase chain reaction(qPCR), and the morphological changes in the liver tissue were performed by hematoxylin-eosin(HE) staining. The results showed that as compared with the model group, the levels of serum uric acid in the positive drug group and the low, medium, and high-dose NMPCS groups were lower(P<0.05), the levels of urine uric acid in the high-dose NMPCS group were decreased(P<0.01), and there was no statistical difference in the medium and low-dose NMPCS groups. The levels of BUN in the high and low-dose NMPCS groups were decreased(P<0.05), and the levels of serum creatinine did not change in the administration groups. The positive drug group and the low, medium, and high-dose NMPCS groups significantly reduced the liver damage, with only a few hepatocytes vacuolization and a small number of red blood cells in the central venous area. The nephridial tissue structure was slightly abnormal, with a small number of red blood cell infiltration, and no obvious inflammatory cell infiltration was found in the glomerulus in these groups. No degeneration was found in renal tubular epithelial cells, with mild glomerular and tubular lesions and a small amount of sodium urate deposition and crystallization in the positive drug group and the low, medium, and high-dose NMPCS groups. The relative protein expressions of XOD in the positive drug group and the high dose NMPCS group were decreased(P<0.05), and the relative mRNA expressions of XOD in the positive drug group and the high and low-dose NMPCS groups were decreased as well(P<0.05). The above results show that NMPCS reduces uric acid in rats with HUA by regulating XOD, which provides a certain experimental basis for the development of NMPCS as a new medicine for the treatment of HUA.

[Effect of application at Shu-Mu acupoint on serum uric acid in hyperuricemic rats].

OBJECTIVE: To observe the effect of application at Back-Shu with Front-Mu acupoints on serum uric acid (SUA) and kidney uric acid transport related proteins in hyperuricemia rats, so as to explore the mechanism of Shu-Mu acupoint application on treatment of hyperuricemia. METHODS: SD rats were randomly divided into blank control, model, vaseline application and medication application groups, with 8 rats in each group. The hyperuricemia rat model was established by gavage of potassium oxonate. Rats in the vaseline application group received application of vaseline at bilateral "Ganshu"(BL18) and "Qimen"(LI14), "Pishu"(BL20) and "Zhangmen"(LR13), "Shenshu" (BL23) and "Jingmen"(GB25). Rats in the medication application group received application of traditional Chinese medicine at the same acupoints. The contents of SUA and creatinine (SCr) were detected by automatic biochemical analyzer. H.E. staining was used to observe the pathological changes of kidney. And the protein expression levels of organic anion transporter 1(OAT1) and adenosine triphosphate binding cassette transporter G2(ABCG2) were detected by immunohistochemistry. RESULTS: Rats in the model group showed symptoms such as polydipsia, polyuria, loose stools, fatigue, weakness, etc. The renal tubules atrophied, and urate crystals can be seen in the lumen. Compared with the control group. the SUA content in the model group increased (P<0.01)and the expressions of OAT1 and ABCG2 protein in kidney decreased (P<0.01). After intervention and in comparison with the model group showed that, the diet, excretion function, and mental state of the rats in the medication application group returned to normal, and the pathological changes of the kidney tissue were alleviated, the SUA content was down-regulated(P<0.01)and the expression levels of OAT1 and ABCG2 in the kidney up-regulated (P<0.01). There was no statistically significant difference in the SCr content among the 4 groups (P＞0.05). CONCLUSION: Medication application at Shu-Mu points can effectively reduce the SUA level of hyperuricemia rats, which may be related to its effects in up-regulating the protein expressions of OAT1 and ABCG2 in the kidney and reducing the damage to the kidneys.

Molecular and Histopathological Study on the Ameliorative Impacts of Petroselinum Crispum and Apium Graveolens against Experimental Hyperuricemia.

Hyperuricemia is an abnormal metabolic condition characterized by an increase in uric acid levels in the blood. It is the cause of gout, manifested by inflammatory arthritis, pain and disability. This study examined the possible ameliorative impacts of parsley (PAR) and celery (CEL) as hypouricemic agents at biochemical, molecular and cellular levels. PAR and CEL alone or in combination were orally administered to hyperuricemic (HU) mice and control mice for 10 consecutive days. Serum levels of uric acid and blood urea nitrogen (BUN), xanthine oxidase activity, antioxidants, inflammatory (IL-1ß and TNF-α) and anti-inflammatory cytokines (IL-10) were measured. mRNA expression of urate transporters and uric acid excretion genes in renal tissues were examined using qRT-PCR (quantitative real time PCR). Normal histology and immunoreactivity of transforming growth factor-beta 1 (TGF-ß1) in kidneys was examined. Administration of PAR and CEL significantly reduced serum BUN and uric acids in HU mice, ameliorated changes in malondialdehyde, catalase, and reduced glutathione, glutathione peroxidase (GPX), IL-1ß, TNF-α and IL-10 in hyperuricemic mice. Both effectively normalized the alterations in mURAT-1, mGLUT-9, mOAT-1 and mOAT-3 expression, as well as changes in TGF-ß1 immunoreactivity. Interestingly, combined administration of PAR and CEL mitigated all examined measurements synergistically, and improved renal dysfunction in the hyperuricemic mice. The study concluded that PAR and CEL can potentially reduce damaging cellular, molecular and biochemical effects of hyperuricemia both individually and in combination.

Identifying mechanisms underlying the amelioration effect of Chrysanthemum morifolium Ramat. 'Boju' extract on hyperuricemia using biochemical characterization and UPLC-ESI-QTOF/MS-based metabolomics.

This study was aimed at evaluating the prospect of edible chrysanthemum extract as a potential substance for the prevention and treatment of hyperuricemia. Chrysanthemum morifolium Ramat. 'Boju' extract (CBE), which had the strongest xanthine oxidase inhibitory activity, showed a significant hypouricemic effect on potassium oxonate-induced hyperuricemic rats through inhibiting serum xanthine oxidase activity, regulating renal uric acid transport-related protein (ABCG2, URAT1 and GLUT9) expression and blood lipid levels, and protecting renal function. Serum metabolomics based on UPLC-ESI-QTOF/MS was used to illustrate mechanisms underlying the amelioration effect of CBE on hyperuricemia. A total of 35 potential biomarkers were identified. CBE prevented the pathological process of hyperuricemia by regulating 16/17 biomarkers associated with tryptophan, sphingolipid, glycerophospholipid and arachidonic acid metabolisms. CBE could alleviate hyperuricemia-related diseases including chronic kidney disease, hyperlipidemia and inflammation via reducing indoxyl sulfate, lysophosphatidylcholines and arachidonic acid levels, exhibiting its applicability and superiority in the treatment of hyperuricemia.

The Effects of Ginsenosides and Anserine on the Up-Regulation of Renal Aquaporins 1-4 in Hyperuricemic Mice.

Hyperuricemia is a metabolic disease of the kidney that results in decreased uric acid excretion. Here, we aimed to investigate the effects of ginsenosides and anserine on hyperuricemia and the expression of aquaporin (AQP) 1-4, which are indicators of renal excretion. Ginsenosides and anserine were administered separately or together after the establishment of hyperuricemia with adenine in BALB/c mice. Renal function indexes such as serum uric acid, creatinine, and urea nitrogen were measured in each group of mice, and the expression of AQP1-4 in renal tissues was detected. Serum uric acid and urea nitrogen were decreased in the ginsenoside and the anserine +UA groups. Meanwhile, the uric acid excretion and clearance rate were clearly increased in the co-treatment +UA group (p<0.05). Moreover, ginsenosides or anserine ginsenosides or anserine alone and treatment with both increased the expression of AQP1-4; however, the synergistic effects were more significantly enhanced (p<0.01). We provide the first reported evidence that ginsenosides and anserine have synergistic effects on uric acid excretion. The improvement in renal function in hyperuricemic mice after treatment with ginsenosides and anserine may result from up-regulation of AQP1-4 expressions.

Modified Chuanhu anti-gout mixture, a traditional Chinese medicine, protects against potassium oxonate-induced hyperuricemia and renal dysfunction in mice.

OBJECTIVE: Acute gout is a painful, inflammatory arthritis that features a rapidly escalating inflammatory response resulting from the formation of monosodium urate crystals in the affected joint space. Previously, we found that Chuanhu anti-gout mixture (CAGM) had similar effects as colchicine against gout in the clinic. Subsequently, to improve its effectiveness and efficacy, we modified the original formulation of CAGM. The current study evaluated the effectiveness of the modified formulation in mice. METHODS: Potassium oxonate (PO) was used to establish a mouse model of hyperuricemia. Plasma levels of uric acid and creatine were determined using the respective test kits. Hepatic xanthine oxidase (XOD) expression was examined by enzyme-linked immunosorbent assay. To explore the underlying mechanism, renal urate transporter 1 (URAT1) mRNA levels were evaluated by quantitative real-time PCR. Allopurinol and benzbromarone were used as reference drugs. RESULTS: The original CAGM and its modified high-dose formulation significantly reduced serum uric acid and creatine levels in hyperuricemic mice. In addition, the CAGM-treated groups displayed lower mRNA levels of hepatic XOD and renal URAT1. CONCLUSIONS: CAGM and its modified formulation significantly ameliorated PO-induced hyperuricemia in mice, which might be partially attributable to reductions of hepatic XOD and renal URAT1 levels.

Effects of ChondroT on potassium Oxonate-induced Hyperuricemic mice: downregulation of xanthine oxidase and urate transporter 1.

BACKGROUND: ChondroT, a new herbal medication, consists of the water extracts of Osterici Radix, Lonicerae Folium, Angelicae Gigantis Radix, Clematidis Radix, and Phellodendri Cortex (6:4:4:4:3). We previously reported that ChondroT showed significant anti-arthritis and anti-inflammatory effects. METHODS: This study was designed to evaluate the effect of ChondroT on hyperuricemia. First, the effect of ChondroT was evaluated on xanthine oxidase (XOD) activity in vitro. The anti-hyperuricemic effect of ChondroT was also studied in potassium oxonate (PO)-induced hyperuricemic model mice. Uric acid (UA) and XOD were evaluated in the serum, urine, and liver of the mice. In addition, we measured serum creatinine (Cr) and blood urea nitrogen (BUN) levels as well as mRNA expression of the mouse urate transporter 1 (mURAT1) to evaluate kidney function and urate excretion in hyperuricemic mice. RESULTS: ChondroT showed in vitro XOD inhibitory activity in a dose-dependent manner (P < 0.05). We demonstrated that ChondroT (37.5, 75 and 150 mg/kg) significantly reduced serum UA (P < 0.01 and P < 0.001, respectively), and upregulated urinary UA (P < 0.001, respectively) in PO-induced hyperuricemic mice. In addition, ChondroT (75 and 150 mg/kg) significantly reduced Cr (P < 0.05 and P < 0.01, respectively), BUN (P < 0.05 and P < 0.001, respectively), GOT (P < 0.05 and P < 0.01, respectively), and GPT (P > 0.05 and P < 0.05, respectively) levels in PO-induced hyperuricemic mice. ChondroT (75 and 150 mg/kg) also significantly downregulated serum (P < 0.05) and liver (P < 0.05) XOD activity. Compared to the hyperuricemic mice, the ChondroT (37.5, 75, and 150 mg/kg)-treated mice showed decreased mURAT1 protein expression level. CONCLUSION: ChondroT displayed anti-hyperuricemic effects by regulating XOD activity and kidney mURAT1.

New Rice-Derived Short Peptide Potently Alleviated Hyperuricemia Induced by Potassium Oxonate in Rats.

Gout that caused by hyperuricemia affects human health seriously and more efficient drugs are urgently required clinically. In this study, a novel peptide named RDP1 (AAAAGAKAR, 785.91 Da) was identified from the extract of shelled fruits of Oryza sativa. Our results demonstrated that RDP1 (the minimum effective concentration is 10 µg/kg) could significantly reduce the serum uric acid and creatinine and alleviate hyperuricemic nephropathy in rats by intragastric administration. RDP1 inhibited xanthine oxidase, which also was verified at the animal level. Results from molecular docking indicated that RDP1 can inhibit uric acid formation by occupying the binding site of xanthine oxidase to xanthine. Besides, RDP1 showed no toxicity on rats and was stable in several temperatures, demonstrating its advantages for transportation. This research was the first discovery of antihyperuricemic peptide from the shelled fruits of O. Sativa and provided a new candidate for the development of hypouricemic drugs.

Antihyperuricemic and xanthine oxidase inhibitory activities of Tribulus arabicus and its isolated compound, ursolic acid: In vitro and in vivo investigation and docking simulations.

BACKGROUND: Hyperurecemia is usually associated with gout and various metabolic arthritis disorders. Limited medications are available to manage such conditions. This study aimed to isolate the triterpenes constituent of the plant and to assess xanthine oxidase (XO) inhibitory and antihyperuricemic activities of Tribulus arabicus ethanolic extract, its fractions and the isolated compound using in vitro and in vivo approaches. METHODS: The ethanolic extract, fractions; n-hexane, chloroform and n-butanol and the isolated compound (ursolic acid) were evaluated in vitro for their XO inhibitory activity. Those that demonstrated significant activity were further evaluated for their antihyperuricemic activity on potassium oxonate-induced hyperuricemia in mice. RESULTS: The ethanolic extract was found to be safe up to 5000 mg/kg. The extract and its n-hexane fraction exhibited significant inhibitory activity on XO, whilst only a modest reduction in the enzymatic activity was noticed with n-butanol and chloroform fractions. Furthermore, administration of the ethanolic extract at low and high doses significantly reduced serum urate levels in mice by 31.1 and 64.6% respectively. The isolated active constituent, ursolic acid, showed potent XO inhibition activity (Half maximal inhibitory concentration, IC50 = 10.3 µg/mL), and significantly reduced uric acid level in vivo by 79.9%. Virtually, the binding mode of ursolic acid with XO was determined using molecular docking simulations. CONCLUSIONS: The activity of the ethanolic extract of T. arabicus and its n-hexane fraction can be attributed to the isolated compound, ursolic acid. Ursolic acid has good hypouricemic activity and therefore has high potential to be used for the treatment of gout and hyperuricemia-related diseases.

Research on the pharmacodynamics and mechanism of Fraxini Cortex on hyperuricemia based on the regulation of URAT1 and GLUT9.

Fraxini Cortex (also known as Qinpi, QP) has been used for the treatment of hyperuricemia with a significant difference on efficacy of QP from different regions. However, it`s still unknown whether proportion of components is the key and why same kind of herbs have different therapeutic effects. In this study, different sources of QP were collected from Shaanxi Qinpi extracts (SQPE), Henan Qinpi extracts (HQPE), Hebei Qinpi extracts (GQPE) provinces in China. Rat model of hyperuricemia with hypoxanthine combined with potassium oxonate were established to determine the levels of blood urea nitrogen (BUN), serum uric acid (SUA), urine uric acid (UUA) and creatinine (Cr). Hematoxylin-eosin staining (H&E) and Periodic Acid-Schiff staining (PAS) were performed for renal pathology while Western blot analysis and real-time PCR analysis for proteins and mRNA expression levels. High-performance liquid chromatograph (HPLC) was used for components and composition analysis. Our results demonstrated that QPE from different regions could alleviate hyperuricemia via increasing significantly the SCr and BUN levels whereas decreasing markedly UCr, SUA and UUA levels. Additionally, QPE could also improve the pathological changes of the kidneys. The protein and mRNA levels of urate reabsorption transporter 1 (URAT1) and glucose transporter 9 (GLUT9) were down-regulated by QPE treatment. SQPE hold a better activity on improving hyperuricemia and regulating URAT1 and GLUT9. HPLC analysis showed that the proportion of four components aesculin, aesculetin, fraxin, fraxetin were 9.002: 0.350: 8.980: 0.154 (SQPE); 0.526: 0.164: 7.938: 0.102 (HQPE); 12.022: 1.65: 0.878: 1.064 (GQPE). These data indicate that this proportion of effective components may be an important factor for efficacy of QP and had implications for the treatment of hyperuricemia.

Genetically high plasma vitamin C and urate: a Mendelian randomization study in 106 147 individuals from the general population.

Objective: Gout is the most common form of inflammatory arthritis and is caused by hyperuricaemia. Some studies have found a reduction in plasma urate with vitamin C supplementation. We tested the hypothesis that high plasma vitamin C is causally associated with low plasma urate and low risk of hyperuricaemia, using a Mendelian randomization approach. Methods: We measured plasma urate and genotyped for the SLC23A1 rs33972313 vitamin C variant in 106 147 individuals from the Copenhagen General Population Study, of which 24 099 had hyperuricaemia. We measured plasma vitamin C in 9234 individuals and genotyped for the SLC2A9 rs7442295 urate variant in 102 345 individuals. Results: Each 10 µmol/l higher plasma vitamin C was associated with a -2.3(95%CI: -0.69 to -3.9) µmol/l lower plasma urate after multivariable adjustments. The SLC23A1 rs33972313 GG genotype was associated with a 9% (5.6%, 11.9%) higher plasma vitamin C compared with AA and AG combined but was not associated with plasma urate (P = 0.31). Likewise, for each 10 µmol/l higher plasma vitamin C the odds ratios for hyperuricaemia were 0.92 (0.86, 0.98) observationally after multivariable adjustments, but 1.01 (0.84, 1.23) genetically. Conclusion: High plasma vitamin C was associated with low plasma urate and with low risk of hyperuricaemia. However, the SLC23A1 genetic variant causing lifelong high plasma vitamin C was not associated with plasma urate levels or with risk of hyperuricaemia. Thus, our data do not support a causal relationship between high plasma vitamin C and low plasma urate.

Hypouricemic Effects of Armillaria mellea on Hyperuricemic Mice Regulated through OAT1 and CNT2.

Ethanol and water extracts of Armillaria mellea were prepared by directly soaking A. mellea in ethanol (AME) at 65[Formula: see text]C, followed by decocting the remains in water (AMW) at 85[Formula: see text]C. Significantly, AME and AMW at 30, 60 and 120[Formula: see text]mg/kg exhibited excellent hypouricemic actions, causing remarkable declines from hyperuricemic control (351[Formula: see text][Formula: see text]mol/L, [Formula: see text]) to 136, 130 and 115[Formula: see text][Formula: see text]mol/L and 250, 188 and 152[Formula: see text][Formula: see text]mol/L in serum uric acid, correspondingly. In contrast to the evident renal toxicity of allopurinol, these preparations showed little impacts. Moreover, they showed some inhibitory effect on XOD (xanthine oxidase) activity. Compared with hyperuricemic control, protein expressions of OAT1 (organic anion transporter 1) were significantly elevated in AME- and AMW-treated mice. The levels of GLUT9 (glucose transporter 9) expression were significantly decreased by AMW. CNT2 (concentrative nucleoside transporter 2), a key target for purine absorption in gastrointestinal tract was involved in this study, and was verified for its innovative role. Both AME and AMW down-regulated CNT2 proteins in the gastrointestinal tract in hyperuricemic mice. As they exhibited considerable inhibitory effects on XOD, we selected XOD as the target for virtual screening by using molecular docking, and four compounds were hit with high ranks. From the analysis, we concluded that hydrogen bond, Pi-Pi and Pi-sigma interactions might play important roles for their orientations and locations in XOD inhibition.

Uric Acid Renal Lithiasis: New Concepts.

BACKGROUND: Uric acid (UA) stones are responsible for 5-10% of the formation of all kidney stones. Recently, an association between UA stones and insulin resistance, diabetes mellitus, and obesity has been demonstrated and so the incidence has increased. The development of UA stones is dependent on several risk factors, including genetic predisposition, geographical location, dietary indiscretion, and various metabolic characteristics. SUMMARY: UA nephrolithiasis can arise from diverse etiologies, all with distinct underlying defects converging to one or more of 3 defects of hyperuricosuria, acidic urine pH, and low urinary volume. Low urinary pH is the commonest and by far the most important factor in UA nephrolithiasis, but the reason for this defect is unknown. Patients with UA nephrolithiasis have normal acid-base parameters assessed according to conventional clinical tests. Studies have revealed that there could be an insufficient production of urinary ammonium buffer. Many transport proteins are candidate participants in urate handling, with URAT1 and GLUT9 being the best characterized to date. Because low urine pH is the most important pathogenic factor of UA stone formation, urine alkalinization is an effective intervention to reduce UA crystallization and dissolve UA stones. Key Messages: Epidemiological and metabolic studies have indicated an association between UA nephrolithiasis and insulin resistance. Some potential mechanisms include impaired ammoniagenesis caused by resistance to insulin action in the renal proximal tubule or due to substrate competition by free fatty acids. The identification of novel complementary DNA has provided an interesting insight into the renal handling of UA, including one genetic cause of renal UA wasting.

Caffeoylquinic acid derivatives rich extract from Gnaphalium pensylvanicum willd. Ameliorates hyperuricemia and acute gouty arthritis in animal model.

BACKGROUND: The Gnaphalium pensylvanicum willd. is used in China as a folk medicine to treat anti-inflammatory, cough and rheumatism arthritis. The aim of this study was to evaluate the potential of the extract of G. pensylvanicum to treat hyperuricemia and acute gouty arthritis in animal model. METHODS: G. pensylvanicum extract was evaluated in an experimental model with potassium oxonate (PO) induced hyperuricemia in mice which was used to evaluate anti-hyperuricemia activity and xanthine oxidase (XO) inhibition. Therapies for acute gouty arthritis was also investigated on monosodium urate (MSU) crystal induced paw edema model. RESULTS: G. pensylvanicum extract showed activity in reducing serum uric acid (Sur) through effect renal glucose transporter 9 (GLUT9), organic anion transporter 1 (OAT1) and urate transporter 1 (URAT1) mainly and inhibited XO activity in vivo of mice with PO induced hyperuricemia. The extract of G. pensylvanicum also showed significant anti-inflammatory activity and reduced the paw swelling on MSU crystal-induced paw edema model. Meanwhile, 13 caffeoylquinic acid derivatives and 1 flavone were identified by UPLC-ESI-MS/MS as the main active component of G. pensylvanicum. CONCLUSIONS: The extract of G. pensylvanicum showed significant effect on evaluated models and therefore may be active agents for the treatment of hyperuricemia and acute gouty arthritis.

Effects of Xie-Zhuo-Chu-Bi-Fang on miR-34a and URAT1 and their relationship in hyperuricemic mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Xie-Zhuo-Chu-Bi-Fang (XZCBF) is an empirical formula that was developed based on the principles of traditional Chinese medicine, for the therapeutic purpose of treating hyperuricemia. XZCBF has been clinically utilized in the Department of Traditional Chinese Medicine at General Hospital of Guangzhou Military Command of PLA for many years and has exhibited favorable efficacy. The aim of the study is to evaluate the effects of XZCBF on the expression of uric acid transporter 1 (URAT1) and miR-34a in hyperuricemic mice and to determine, the correlation between the two expression levels. MATERIALS AND METHODS: A hyperuricemic animal model was created by administering adenine and allantoxanic acid potassium salt to mice. The blood uric acid levels were measured in these model mice after treatment with XZCBF for 15 days. The potential targets of miR-34a were screened. The expression levels of miR-34a and URAT1 in the renal tissues collected from the model mice were determined by quantitative real-time polymerase chain reaction (qRT-PCR) analysis, and their correlation was further established by immunohistochemistry and in situ hybridization. RESULTS: The uric acid levels in the model mice were significantly higher than those in the blank controls (P<0.05). These levels were significantly lower in the three groups receiving different doses of XZCBF (P<0.05), which was, in agreement with the downregulation of URAT1 and the upregulation of miR-34a in each group. The mRNA expression level of URAT1 was positively correlated with the concentration of uric acid but, negatively correlated with the expression level of miR-34a. CONCLUSIONS: The ability of XZCBF to facilitate the excretion of uric acid and to lower its level in the model group was mediated by the upregulation of miR-34a and the inhibition of URAT1 mRNA expression, which suggests that XZCBF could be an option for the treatment of hyperuricemia in mice.

Administered chrysanthemum flower oil attenuates hyperuricemia: mechanism of action as revealed by DNA microarray analysis.

We applied Chrysanthemum flower oil (CFO) to a hyperuricemia model by feeding rats a hyperuricemia-inducing diet (HID) and investigated its effect on serum uric acid (SUA) levels and its mode of action. CFO is the oily fraction that contains polyphenols derived from chrysanthemum flowers. Oral administration of CFO to HID-fed rats significantly decreased their SUA levels. It also inhibited xanthine oxidase activities in the liver and increased urine uric acid levels. The effects of CFO on the renal gene expressions that accompanied the induction of hyperuricemia were comprehensively confirmed by DNA microarray analysis. The analysis showed up-regulation of those genes for uric acid excretion by CFO administration. These results suggest that CFO suppresses the increase in SUA levels via two mechanisms: suppression of uric acid production by inhibition of xanthine oxidase in the liver and acceleration of its excretion by up-regulation of uric acid transporter genes in the kidney.