Reduced Serum Uric Acid Levels Research Articles

Artemisia selengensis Turcz. leaves extract ameliorates hyperuricemia in mice by inhibiting hepatic xanthine oxidase activity, modulating renal uric acid transporters, and improving metabolic disorders

Artemisia selengensis Turcz. (AST) is a common edible and medicinal herb with multiple health benefits. Our previous research indicated that AST leaves, by-products of AST, possess strong in vitro xanthine oxidase (XOD) inhibitory activity, making them a potential treatment for hyperuricemia (HUA). In this study, we investigated the anti-HUA effect of AST leaves extract (ASTLE) in HUA mice and explore the underlying mechanisms. Chemical analysis showed that ASTLE is rich in caffeoylquinic acids (CQAs), including four mono-CQAs (1-CQA, 3-CQA, 5-CQA, and 4-CQA) and six di-CQAs (1,3-diCQA, 1,4-diCQA, 3,4-diCQA, 1,5-diCQA, 3,5-diCQA, and 4,5-diCQA). In HUA mice, ASTLE reduced serum uric acid level and increased urine uric acid level and fraction excretion of uric acid. ASTLE also protected against liver and kidney damage, as evidenced by decreased serum levels of glutamic oxaloacetic transaminase, glutamic-pyruvic transaminase, creatinine, and blood urea nitrogen. After ASTLE intervention, the hepatic XOD activity was inhibited. Additionally, the mRNA expression of mURAT1 and mGLUT9 was down-regulated, while the mRNA expression of mABCG2, mOAT1, and mOAT3 was up-regulated. Metabolomic analysis further suggested that ASTLE mainly regulated amino acids and their metabolites, which are associated with renal uric acid excretion function. These results demonstrate that ASTLE rich in CQAs, has beneficial effects against HUA in mice by inhibiting hepatic XOD activity, modulating the mRNA expression of renal uric acid transporters, and improving metabolic disorders in HUA mice. Our findings suggest that AST leaves may be a promising natural resource for ameliorating HUA.

#5599 FEBUXOSTAT IN COMBINATION WITH ANAKINRA OR PH NEUTRALIZATION IMPROVE THE OUTCOMES IN HYPERURICEMIA-RELATED URIC ACID CRYSTALLURIA IN MICE

Abstract Background and Aims Currently, it is unknown whether CKD patients with hyperuricemia (HU)-related uric acid (UA) crystalluria, also known as chronic UA nephropathy, would benefit from targeting HU, UA crystallization, and/or inflammation to slow down the progressive decline of kidney function. Although large multi-center RCTs with xanthine oxidase inhibitors (XOIs) such as allopurinol and two Mendelian randomization studies have disproven a causal link between HU and CKD progression, one cannot rule out that XOIs may still represent a viable therapeutic approach for patients with HU-related UA crystalluria in order to prevent CKD progression. This issue requires clarification. To address this, we used our well-established CKD mouse model of HU with UA crystalluria and tested numerous therapeutic approaches including XOI and anakinra. Method Alb-creERT2;Glut9lox/lox (male and female) mice were injected with tamoxifen and placed on an acidogenic diet with the purine inosine to induce HU and crystalluria-related CKD. After chronic UA nephropathy was established on day 14, mice were treated either 1) with the XOIs allopurinol or febuxostat, 2) with sodium bicarbonate supplementation to neutralize urinary pH to prevent UA crystallization, or 3) with anakinra to inhibit IL-1β-driven inflammation, or 4) a combination of the aforementioned therapies for 2 weeks. Saline was used as control. On day 0, 14, and 28, GFR (as primary endpoint) as well as serum UA levels and urinary UA crystals (as secondary endpoints) were determined. At the end of the study, we quantified kidney injury, immune cell infiltration, inflammation, and interstitial fibrosis using histological analysis, ELISA, RT-qPCR, and flow cytometry. Results Therapy with XOIs but not with sodium bicarbonate and anakinra reduced serum UA levels in mice with HU and UA crystalluria. Treating mice with febuxostat improved kidney function (increase in GFR) by preventing kidney injury, UA crystalluria, UA crystal granuloma formation, and interstitial fibrosis compared with the control group, while allopurinol worsened the outcomes of chronic UA nephropathy. On the other hand, sodium bicarbonate supplementation had no effects on serum UA levels, kidney inflammation, immune cell infiltration and interstitial fibrosis but improved kidney function due to less urinary UA crystal deposition (neutralization of urine pH) and granuloma formation as compared with saline-treated mice. As expected, anakinra did not slow down the progression of chronic UA nephropathy as noticed by a similar GFR decline compared with the control group. Although, anakinra reduced the number of infiltrating immune cells and the mRNA expression of inflammatory mediators in the kidney as well as the serum IL-1β concentrations, we observed more interstitial fibrosis. In combination, allopurinol with anakinra did not improve the outcomes of chronic UA nephropathy despite the inhibitory effect of anakinra on the inflammatory response because allopurinol triggered tubulointerstitial nephritis and vasodilation. Interestingly, both combination therapies febuxostat with anakinra and febuxostat with sodium bicarbonate were protective by improving kidney function and preventing UA crystal deposition, kidney injury, inflammation, interstitial fibrosis and UA crystal granuloma formation compared with the single therapies. Conclusion Our interventional study is the first pre-clinical study, which reveals that the XOIs allopurinol and febuxostat have differential effects on the outcomes of HU-related UA crystalluria. While allopurinol contributes to the progression of CKD by causing tubulointerstitial nephritis in mice, febuxostat rather seems to be renoprotective similar to urinary pH neutralization with sodium bicarbonate. We identified both combination therapies febuxostat with anakinra or sodium bicarbonate as most beneficial in order to prevent CKD progression in mice. Thus, febuxostat in combination with IL-1β inhibition or prevention of urinary UA crystallization may represent therapeutic approaches for patients with chronic UA nephropathy.

Sex distinctive patterns in the association between serum bicarbonate and uric acid levels among healthy adults. Qatar biobank data.

Uric acid is the final product of purine metabolism and is a potent plasma antioxidant but with pro-inflammatory effects. At high levels, it may increase the risk of developing multiple chronic diseases, such as gout, atherosclerosis, hypertension, and renal diseases. The aim of this study was to assess the sex-specific association between serum bicarbonate and uric acid levels among healthy adults. This retrospective cross-sectional study included 2,989 healthy Qatari adults (36.4 ± 11.1 years) from the Qatar Biobank database. Serum uric acid and bicarbonate levels were estimated alongside other serological markers. Participants free from chronic diseases were divided into four quartiles based on serum bicarbonate levels. The sex-specific relationship between serum bicarbonate and uric acid levels was assessed through univariate and multivariate analyses. In men, low serum uric acid levels were significantly associated with higher quartiles of serum bicarbonate levels after adjusting for age. The association remained significant after further adjustment for BMI, smoking, and renal function. The subgroup analysis using the restricted cubic spline method confirmed a significant dose-response association between the variation coefficients of uric acid by serum bicarbonate level in men with adjustments for age, BMI, smoking, and renal function. In women, no significant association was found between quartiles of serum bicarbonate and uric acid levels following the same adjustments. However, using the restricted cubic spline method, a significant bidirectional relation was demonstrated between serum bicarbonate and the variation coefficients of uric acid that were positive for serum bicarbonate levels below 25 mEq/L and negative at higher levels. Serum bicarbonate levels are linearly associated with reduced serum uric acid levels among healthy adult men, which may be a potential protective factor against hyperuricemia-related complications. Further research is needed to determine the underlying mechanisms.

Association Between Serum Uric Acid and Non-Alcoholic Fatty Liver Disease: An Updated Systematic Review and Meta-Analysis.

Recent epidemiological evidence shows that there is an association between serum uric acid (SUA) levels and nonalcoholic fatty liver disease (NAFLD). The purpose of this meta-analysis is to summarize all available evidence and assess the associations between SUA levels and NAFLD. Using two databases, Web of Science and PubMed, observational studies were applied from the establishment of the databases to June 2022. We used a random effect model to construct the pooled odds ratio (OR) and 95% confidence interval (CI) to appraise the association between SUA levels and NAFLD. The Begg's test was conducted to appraise publication bias. A total of 50 studies were included, involving 2,079,710 participants (719,013 NAFLD patients). The prevalence and incidence rates (95% CIs) of NAFLD in the patients with hyperuricemia were 65% (57-73%) and 31% (20-41%), respectively. Compared to participants with lower levels of SUA, the pooled OR (95% CI) of NAFLD in those with higher levels of SUA was 1.88 (95% CI: 1.76-2.00). In the subgroup analyses, we found that SUA levels were positively associated with NAFLD in all subgroups, according to study design, study quality, sample size, sex, comparison, age, or country. This meta-analysis shows that increased SUA levels are positively associated with NAFLD. The results suggested that reducing SUA levels can be a potential strategy for the prevention of NAFLD. PROSPERO-CRD42022358431.

Emodin, a Natural Anthraquinone, Increases Uric Acid Excretion in Rats with Potassium Oxonate-Induced Hyperuricemia.

The treatment of hyperuricemia and gout is mostly based on lowering serum uric acid levels using drugs, such as allopurinol, or increasing urinary excretion of uric acid. However, some patients still experience adverse reactions to allopurinol and turn to Chinese medicine as an alternative. Therefore, it is crucial to design a preclinical study to obtain more convincing data on the treatment of hyperuricemia and gout with Chinese medicine. This study aimed to explore the therapeutic effect of emodin, a Chinese herbal extract, in a rat model of hyperuricemia and gout. In this study, we used 36 Sprague-Dawley rats, which were randomly divided into six groups for experimentation. Hyperuricemia was induced in rats by intraperitoneal injections of potassium oxonate. The efficacy of emodin in reducing serum uric acid levels was demonstrated by comparing the positive control group with groups treated with three different concentrations of emodin. The inflammatory profiles, including interleukin (IL)-1β, IL-6, and tumor necrosis factor-α levels, were unaffected by emodin treatment. In the experimental results, it was observed that the serum uric acid concentration in the vehicle control group was 1.80 ± 1.14, while the concentrations in the moderate and high concentration emodin groups were 1.18 ± 0.23 and 1.12 ± 0.57, resulting in no significant difference in uric acid concentration between these treatment groups and the control group, indicating that emodin has a therapeutic effect on hyperuricemia. The increase in the fractional excretion of uric acid (FEUA) demonstrated that emodin promoted urinary uric acid excretion without significantly affecting the inflammatory profile. Thus, emodin reduced the serum uric acid concentration to achieve effective treatment of hyperuricemia and gout by increasing urinary excretion. These results were supported by the measured serum uric acid and FEUA levels. Our data have potential implications for the treatment of gout and other types of hyperuricemia in clinical practice.

The association of serum uric acid with all-cause and cardiovascular mortality among adults with rheumatoid arthritis: a cohort study.

Serum uric acid (SUA) is associated with poor outcomes in patients with numerous types of disease. However, the association between SUA and the outcomes of patients with rheumatoid arthritis (RA) remains to be fully elucidated. Thus, the present study aimed to determine the associations between SUA and all-cause or cardiovascular disease (CVD)-associated mortality in adults with RA. The data of patients with RA were collected from the National Health and Nutrition Examination Survey from 2001 to 2018. All-cause and CVD-associated mortality were identified using national death records through 31 December 2019. Weighted survival curves, Cox proportional hazards regression models, restricted cubic splines (RCS) and stratified analyses were used to assess the association between SUA levels and mortality. Among 2,312 patients with RA, a total of 597 all-cause deaths and 198 CVD-associated deaths were recorded during 19,133 person-years of follow-up. The results of the Kaplan-Meier curves for long-term all-cause and CVD-associated mortality demonstrated that increased levels of SUA were associated with a higher incidence of mortality. In the fully adjusted models, the highest SUA quartile exhibited hazard ratios [(HRs); 95% confidence intervals (CIs)] of 1.53 (1.10, 2.14) for all-cause mortality and 1.93 (1.14, 3.27) for CVD-associated mortality, compared with the lowest SUA quartile. The results of the RCS analysis confirmed a strong linear association between SUA levels and the HR of all-cause mortality, while a U-shaped association was observed between SUA and CVD-associated mortality. The results of the present study demonstrated that high SUA levels were significantly associated with increased risks of all-cause and CVD-associated mortality in patients with RA. Further studies are required to elucidate the potential impact of treatments on reducing SUA levels.

Naringenin Prevents Renal Injury in Experimental Hyperuricemia Through Suppressing Xanthine Oxidase, Inflammation, Apoptotic Pathway, DNA Damage, and Activating Antioxidant System.

Background/Purpose: This research was performed to determine the effect of naringenin (NAR) in experimental hyperuricemia (HU) induced by potassium oxonate (PO) on uric acid levels and xanthine oxidase (XO), inflammation, apoptotic pathway, DNA damage, and antioxidant system in kidney tissue. Study Design: Wistar Albino rats were categorized into four groups: (1) Control group, (2) PO group, (3) [PO+NAR] (2 weeks) group, and (4) PO (2 weeks)+NAR (2 weeks) group. Methods: The first group was not administered any drug. In group 2, PO was administered intraperitoneally 250 mg/kg/day for 2 weeks. In the third group, 100 mg/kg/day NAR was given intraperitoneally 1 hr after PO injection for 2 weeks. In the fourth group, PO was injected for the first 2 weeks, followed by NAR injection for the second 2 weeks. Serum uric acid levels, XO, nuclear factor-kappa B, tumor necrosis factor-alpha, interleukin-17, cytochrome c, 8-Hydroxydeoxyguanosine (8-OHdG), glutathione peroxidase (GPx), and caspase-3 levels in kidney were determined. Results: HU increased the levels of inflammatory and apoptotic parameters, XO, and 8-OHdG levels in kidney. Administration of NAR caused a decrease in these values and an increase in GPx levels. Conclusions: The results of the study show that NAR treatment reduces serum uric acid levels, and apoptosis, inflammation, and DNA damage; increases antioxidant activity in kidney in experimental HU.

Amelioration effects of α-viniferin on hyperuricemia and hyperuricemia-induced kidney injury in mice

Backgroundα-Viniferin, the major constituent of the roots of Caragana sinica (Buc'hoz) Rehder with a trimeric resveratrol oligostilbenoid skeleton, was demonstrated to possess a strong inhibitory effect on xanthine oxidase in vitro, suggesting it to be a potential anti-hyperuricemia agent. However, the in vivo anti-hyperuricemia effect and its underlying mechanism were still unknown. PurposeThe current study aimed to evaluate the anti-hyperuricemia effect of α-viniferin in a mouse model and to assess its safety profile with emphasis on its protective effect on hyperuricemia-induced renal injury. MethodsThe effects were assessed in a potassium oxonate (PO)- and hypoxanthine (HX)-induced hyperuricemia mice model by analyzing the levels of serum uric acid (SUA), urine uric acid (UUA), serum creatinine (SCRE), serum urea nitrogen (SBUN), and histological changes. Western blotting and transcriptomic analysis were used to identify the genes, proteins, and signaling pathways involved. Resultsα-Viniferin treatment significantly reduced SUA levels and markedly mitigated hyperuricemia-induced kidney injury in the hyperuricemia mice. Besides, α-viniferin did not show any obvious toxicity in mice. Research into the mechanism of action of α-viniferin revealed that it not only inhibited uric acid formation by acting as an XOD inhibitor, but also reduced uric acid absorption by acting as a GLUT9 and URAT1 dual inhibitor as well as promoted uric acid excretion by acting as a ABCG2 and OAT1 dual activator. Then, 54 differentially expressed (log2 FPKM ≥ 1.5, p ≤ 0.01) genes (DEGs) repressed by the treatment of α-viniferin in the hyperuricemia mice were identified in the kidney. Finally, gene annotation results revealed that downregulation of S100A9 in the IL-17 pathway, of CCR5 and PIK3R5 in the chemokine signaling pathway, and of TLR2, ITGA4, and PIK3R5 in the PI3K-AKT signaling pathway were involved in the protective effect of α-viniferin on the hyperuricemia-induced renal injury. Conclusionsα-Viniferin inhibited the production of uric acid through down-regulation of XOD in hyperuricemia mice. Besides, it also down-regulated the expressions of URAT1 and GLUT9 and up-regulated the expressions of ABCG2 and OAT1 to promote the excretion of uric acid. α-Viniferin could prevent hyperuricemia mice from renal damage by regulating the IL-17, chemokine, and PI3K-AKT signaling pathways. Collectively, α-viniferin was a promising antihyperuricemia agent with desirable safety profile. This is the first report of α-viniferin as an antihyperuricemia agent.

Development of a novel anti-inflammatory recombinant uricase with extended half-life for gout therapy

Gout is a form of inflammatory arthritis that results from elevated serum uric acid levels and the deposition of urate crystals in multiple joints. The inflammatory response during an acute gout attack is mediated by the activation of the NLRP3 inflammasome, leading to the release of IL-1β and inducing a localized tissue inflammatory response. Urate lowering therapies such as Pegloticase effectively reduce serum uric acid levels but are generally associated with an increase in acute gout flares. In this study, we developed a long-acting anti-inflammatory recombinant uricase by sequential fusing interleukin-1 receptor antagonist (IL-1Ra) and albumin-binding domain (ABD) with the N-terminal end of Arthrobacter globiformis uricase (AgUox). The recombinant uricase has longer in vivo half-life, and significantly alleviates monosodium urate (MSU) crystals induced inflammation in mouse model compared with the wild-type AgUox. This long-acting anti-inflammatory recombinant uricase has the potential to be developed as an effective urate lowering therapy with better safety profiles.

The effect of dapagliflozin on uric acid excretion and serum uric acid level in advanced CKD

Sodium–glucose cotransporter 2 inhibitors (SGLT2i) exhibit renoprotective effect in patients with chronic kidney disease (CKD) and reduce serum uric acid (UA) in patients with diabetes mellitus. However, it is not clarified whether SGLT2i reduce serum UA levels in patients with advanced CKD. This study aimed to investigate the impact of SGLT2i on change in serum UA levels in patients with advanced CKD. Data of 121 Japanese patients with CKD who were newly administered 10 mg dapagliflozin in our department between August 2021 and August 2022 were analyzed. Changes in UA and fractional excretion of UA (FEUA) were analyzed using multiple regression analysis. Of 75 patients, 21 (28.0%) patients, 24 (32.0%) patients, 29 (38.7%) patients, and 1 (1.3%) patient were categorized as having CKD stage 3a, 3b, 4, and 5, respectively. The median age was 67 years, and 72.0% were male. 23 (30.7%) of patients had diabetes mellitus. The median estimated glomerular filtration rate, serum UA, and FEUA were 35.7 mL/min/1.73 m2, 6.4 mg/dL, and 6.76%, respectively, at the time of dapagliflozin administration. After administration, serum UA decreased to 5.6 mg/dL and FEUA increased to 9.22%. Dapagliflozin increases FEUA and reduces serum UA levels in patients with advanced CKD.

Urate Transporter 1 Can Be a Therapeutic Target Molecule for Chronic Kidney Disease and Diabetic Kidney Disease: A Retrospective Longitudinal Study.

Chronic kidney disease (CKD) is a major global health problem for which there are no curative drug treatments. Hyperuricemia is one of risk factors for CKD. The evidence on effects of uric acid (UA)-lowering treatments on the progression of CKD was very limited and previous meta-analyses used only trials which primarily used xanthin oxidase (XO) inhibitors because the reports on fulminant hepatitis due to benzbromarone kept us from using uricosuric agents for hyperuricemia patients. Dotinurad, a novel selective urate reabsorption inhibitor for the treatment of hyperuricemia, reduces serum UA levels by selectively inhibiting urate transporter 1 (URAT1). We retrospectively picked up patients who had taken dotinurad from June 2018 to August 2021 and compared metabolic parameters at baseline with the data at 3 and 6 months after the start of dotinurad. We found 84 patients, and approximately 74% of patients were complicated with CKD. After the start of dotinurad, improvements in serum lipids, systolic blood pressure, body weight, and albuminuria, in addition to reduction in serum UA, were observed. Dotinurad increased urinary UA excretion, and was effective to reduce serum UA in patients with both UA underexcretion type and renal UA overload type. Furthermore, urinary UA excretion was significantly and negatively correlated with serum creatine levels at baseline and at 6 months after the start of dotinurad, and the change in urinary UA excretion after 3 months was significantly and negatively correlated with change in serum creatine levels. The property of dotinurad, which selectively inhibits URAT1, but not other UA transporters, such as ATP-binding cassette, subfamily G, and 2 (ABCG2), which ABCG2 is a UA and uremic toxin exporter, may be beneficially associated with pathology of CKD. URAT1 can be a therapeutic target molecule for CKD and DKD.

The Impact of Obesity Surgery on Serum Uric Acid in People With Severe Obesity: A Retrospective Study.

Studies indicate an association between hyperuricemia (HUA) and metabolic syndrome risk factors. On the other hand, obesity is a major modifiable and independent risk factor for HUA and gout. However, evidence concerning the effects of bariatric surgery on serum uric acid levels is limited and not completely clarified. This retrospective study was carried out with 41 patients who underwent sleeve gastrectomy (n = 26) and Roux-en-Y gastric bypass (n = 15) from September 2019 to October 2021. Anthropometric, clinical, and biochemical data, including uric acid blood urea nitrogen and creatinine fasting blood sugar (FBS), serum triglyceride (TG), and serum cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), were measured preoperatively and postoperative 3, 6 and 12 months. From baseline to 6 and 12 months, bariatric surgery resulted in a significant decrease in serum uric acid of patients with severe obesity (p < 0.001). The decreases in serum FBS, TG, and cholesterol of patients were significant during 6 and 12 months of follow-up (p < 0.05). However, the HDL increase of patients was not statistically significant in 6 and 12 months (p > 0.05). Besides, although patients' serum level of LDL decreased significantly during the 6 months of follow-up (p = 0.007), it was not significant after 12 months (p = 0.092). Bariatric surgery significantly reduces serum uric acid levels. Therefore, it may be an effective supplementary therapy for lowering serum uric acid concentrations in morbidly obese patients.

Effects of a Macroporous Resin Extract of Dendrobium officinale Leaves in Rats with Hyperuricemia Induced by Anthropomorphic Unhealthy Lifestyle.

Hyperuricemia (HUA) has received increased attention in the last few decades due to its global prevalence. Our previous study found that administration of a macroporous resin extract of Dendrobium officinale leaves (DoMRE) to rats with HUA that was induced by exposure to potassium oxazine combined with fructose and a high-purine diet led to a significant reduction in serum uric acid (SUA) levels. The aim of this study was to explore the effects of DoMRE on hyperuricemia induced by anthropomorphic unhealthy lifestyle and to elucidate its possible mechanisms of action. Dosages (5.0 and 10.0 g/kg/day) of DoMRE were administered to rats daily after induction of HUA by anthropomorphic unhealthy lifestyle for 12 weeks. The levels of UA in the serum, urine, and feces; the levels of creatinine (Cr) in the serum and urine; and the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum were all measured using an automatic biochemical analyzer. The activities of xanthine oxidase (XOD) and adenosine deaminase (ADA) in the serum, liver, and intestine tissue supernatant were measured using appropriate kits for each biological target. The expressions levels of UA transporters (ABCG2 and GLUT9), tight junction (TJ) proteins (ZO-1 and occludin), and inflammatory factors (IL-6, IL-8, and TNF-α) in the intestine were assayed by immunohistochemical (IHC) staining. Hematoxylin and eosin (H&E) staining was used to assess histological changes in the renal and intestinal tissues. DoMRE treatment significantly reduced SUA levels and concomitantly increased fecal UA (FUA) levels and the fractional excretion of UA (FEUA) in HUA rats. Furthermore, DoMRE significantly reduced both the XOD activity in the serum, liver, and intestine and the ADA activity in the liver and intestine. DoMRE also effectively regulated the expression of GLUT9 and ABCG2 in the intestine, and it significantly upregulated the expression of the intestinal TJ proteins ZO-1 and occludin. Therefore, DoMRE reduced the damage to the intestinal barrier function caused by the increased production of inflammatory factors due to HUA to ensure normal intestinal UA excretion. DoMRE demonstrated anti-HUA effects in the HUA rat model induced by an anthropomorphic unhealthy lifestyle, and the molecular mechanism appeared to involve the regulation of urate transport-related transporters (ABCG2 and GLUT9) in the intestine, protection of the intestinal barrier function to promote UA excretion, and inhibition of XOD and ADA activity in the liver and intestine to inhibit UA production in the HUA-induced rats.

Bioactivity and Component Analysis of Water Extract of Sophora japonica against Hyperuricemia by Inhibiting Xanthine Oxidase Activity.

Hyperuricemia (HUA) is a metabolic condition caused by excessive production or low excretion of uric acid (UA) in the body. Xanthine oxidase (XOD) is the key enzyme in the process of metabolism purines to generate UA. In this study, the in vitro inhibitory effect of water extract of the flower bud of Sophora japonica (WESJ) on XOD was investigated by ultraviolet spectrophotometry. A mice model of HUA was constructed to explore the effect of WESJ on UA levels and the mechanism of action on renal function. Based on Box-Behnken design, the optimal extraction process of WESJ was determined to extract Sophora japonica twice with 8 times of water, 0.5 h each time. Pharmacological results showed that low, medium, and high doses of WESJ (200, 400, 600 mg/kg) could significantly reduce serum UA level, inhibit the activity of XOD in blood and liver, and have a protective effect on kidney damage caused by high UA. Through UPLC-Q-TOF-MS/MS analysis, 214 compounds were identified in WESJ, including flavonoids, polyphenols, triterpenoids, organic acids, and others. The rat serum of WESJ was analyzed, and 23 prototype components entering the blood were identified, including 15 flavonoids and polyphenols, which may be the main bioactive components. In conclusion, flavonoids and polyphenols in WESJ may reduce the level of UA and alleviate kidney damage by inhibiting the activity of XOD. WESJ is expected to be used as a plant-based food and dietary supplement for the treatment of HUA.

Exercise serum regulates uric acid transporters in normal rat kidney cells

Hyperuricemia (HUA) refers to a physiological condition of high serum uric acid (SUA) level in the body, which may cause an increased risk of several chronic diseases. The kidney’s impaired uric acid (UA) metabolism is an important reason for HUA. In this study, we tested the hypothesis that circulating factors produced during exercise regulate the expression of ABCC4, ABCG2, URAT1, and GLUT9 in normal rat kidneys and normal rat kidney cells (NRK-52E) and their relationship with NF-κB and NRF-2. NRK-52E cells were separately cultured by serum from 10 healthy SD rats who did not exercise (CON) and 10 healthy SD rats who did aerobic treadmill exercise for 6 weeks. Cells cultured by serum from rats who did aerobic treadmill exercise for 6 weeks were separated by without NRF-2 inhibitor (EXE) and with NRF-2 inhibitor (EXE + ML). SUA level of rats was tested by using dry chemical assays, xanthine oxidase (XOD) activity in serum and liver were tested by using enzyme colorimetry assays, protein expression in kidney and NRK-52E cells were tested by using Western-blot, and UA levels in the upper or lower chamber were tested by colorimetry assays. Aerobic exercise reduced SUA levels in rats but did not significantly affect on liver xanthine oxidase. It also increased the expression of some UA transporters in the kidney and NRK-52E cells and increased the cells’ ability in UA excretion. When the NRF-2 was inhibited, the NF-κB and ABCG2 increased, and the expression of ABCC4, URAT1, and GLUT9 decreased. In conclusion, this study suggested that 6 weeks of aerobic treadmill exercise intervention may help to improve the excretion of UA in renal cells, suggesting that long-term aerobic exercise may be a means to prevent hyperuricemia.

Preparation of an isorhamnetin phospholipid complex for improving solubility and anti-hyperuricemia activity

To improve the solubility and anti-hyperuricemia activity of the insoluble natural flavonoid isorhamnetin (ISO), an isorhamnetin phospholipid complex (ISO-PC) was prepared. ISO-PC was prepared through solvent evaporation and its prescription process was optimized. The formation of ISO-PC was verified via multiple characterization methods. Parameters such as drug loading, solubility, octanol-water partition coefficient, stability, and in vivo anti-hyperuricemia activity of ISO-PC were investigated. The complexation efficiency of ISO-PC was 95.1% ± 0.56%. The characterization results confirmed that ISO-PC was bound by intermolecular interactions between ISO and phospholipids. Compared with ISO, the solubility of ISO-PC in water and 1-octanol increased by 122 and 16.5 times, respectively. In addition, the octanol-water partition coefficient decreased to 1.08. Pharmacodynamic studies have reported that ISO-PC has a more significant effect on reducing serum uric acid levels and renal protection. In conclusion, the findings of this study suggested that ISO-PC could be used as a promising formulation to improve the solubility and the anti-hyperuricemia activity of ISO.

Effects of allopurinol on renal function in patients with diabetes: a systematic review and meta-analysis

Background/Objective Diabetes mellitus is a common “non-gout” disease with high incidence. Several studies have shown that serum uric acid level in patients with diabetes is higher than that in healthy individuals, and is accompanied by severe albuminuria and high serum creatinine (Scr). Recent clinical studies have found that uric acid-lowering therapy (such as allopurinol) could reduce urinary albumin excretion rates (UAER) and Scr, increase eGFR, and thus reduce kidney damage in patients with diabetes. Therefore, this meta-analysis [PROSPERO CRD42021274465] intended to evaluate the efficacy and safety of allopurinol in patients with diabetes mellitus. Methods We thoroughly searched five electronic resource databases for randomized controlled trials (RCTs) that compared the efficacy and safety of allopurinol versus conventional treatment or placebo for the treatment of patients with diabetes mellitus. Predetermined outcomes were considered continuous variables, mean difference (MD) was used for the determination of effect size (standardized mean difference [SMD] was used to determine the effect size when there were different evaluation criteria in different articles), and the corresponding 95% confidence interval (CI) was calculated. All outcome measures were analyzed using a random-effects model for data analysis. Results Ten eligible trials with a total of 866 participants were included in the meta-analysis. Allopurinol was more effective in decreasing serum uric acid (SUA) levels compared with conventional treatment (p = 0.0001) or placebo (p < 0.00001). Moreover, the levels of 24-hour urine protein were significantly lower in the allopurinol group (p < 0.00001). The subgroup analysis of Scr showed that the Scr of patients with an allopurinol treatment duration of fewer than six months was significantly lower than that of the control group (p = 0.03). No significant difference in adverse events (AEs) was identified between the treatment and control groups. Conclusions Our meta-analysis of RCTs showed that oral administration of allopurinol effectively reduced SUA levels in patients with diabetes, and patients’ renal function was protected. More RCTs with larger sample sizes and higher quality are needed to clarify the role of allopurinol use in decreasing blood pressure, maintaining blood glucose levels, and improving renal function in patients with diabetes.

An integrated study of Shenling Baizhu San against hyperuricemia: Efficacy evaluation, core target identification and active component discovery

Ethnopharmacological relevanceShenling Baizhu San (SLBZ) is a famous Traditional Chinese Medicine (TCM) formula that strengthens the spleen for replenishing qi, removing dampness, and inducing diuresis to relieve diarrhea. Combining the TCM interpretation that dampness is a vital pathogenesis factor in hyperuricemia occurrence and development, SLBZ has excellent potential against hyperuricemia from the perspective of TCM theories. Aim of the studyThis study aimed to investigate the efficacy of SLBZ against hyperuricemia and its possible mechanism with emphasis on the active components and the core targets. Materials and methodsIn the present study, we employed meta-analysis and a hyperuricemia quail model to evaluate the uric acid-lowering effect of SLBZ. Bodyweight, serum uric acid, and excreta uric acid levels in quails were assessed. Subsequently, we analyzed the potential active components and core targets of SLBZ against hyperuricemia by network pharmacology and calculated their interaction using molecular docking. Furthermore, the hyperuricemia rats treated with interfering agents of core targets were established to determine the central role of selected targets in hyperuricemia progression. Besides, we isolated and characterized the primary renal tubular epithelial cells of quails to verify the active components and core targets of SLBZ against hyperuricemia. Western blotting was used to observe the expression of core targets treated with active components under the stimulation of interfering agents. ResultsData from meta-analysis and animal experiments showed that SLBZ could work effectively against hyperuricemia. Hyperuricemia quails treated with SLBZ displayed significantly reduced serum uric acid levels accompanied by increased excretion of uric acid. According to network pharmacology and molecular docking results, 34 potential active components and the core target peroxisome proliferator-activated receptor gamma (PPARγ) for SLBZ against hyperuricemia were identified. The decreased serum uric acid levels in hyperuricemia rats treated with rosiglitazone, an agonist of PPARγ, confirms the essential role of PPARγ in the pathological process of hyperuricemia. Moreover, we first successfully isolated and characterized the primary renal tubular epithelial cells of quails and observed enhanced phosphorylation of PPARγ at Ser273 in cells handled with high-level uric acid. Whereas, the enhanced expression of p-PPARγ Ser273 could be down-regulated by luteolin and naringenin, two active components of SLBZ against hyperuricemia. ConclusionIn summary, SLBZ is a promising anti-hyperuricemia agent, and luteolin and naringenin are the active components for SLBZ against hyperuricemia by down-regulating phosphorylation of PPARγ at Ser273.

TIME-VARYING SERUM URIC ACID PREDICTS NEW-ONSET ATRIAL FIBRILLATION IN TREATED HYPERTENSIVE PATIENTS

Objective: The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study was the first clinical outcome trial to suggest that lowering of serum uric acid by a uricosuric drug such as losartan has a beneficial effect on cardiovascular outcome independently of changes in renal function or blood pressure. LIFE also showed less new-onset atrial fibrillation in hypertensive patients receiving losartan vs. atenolol based treatment. Because losartan reduces serum uric acid levels, we investigated relations of serum uric acid with new-onset atrial fibrillation in the study. Design and method: Hypertensive patients with electrocardiographic left ventricular hypertrophy and no prior atrial fibrillation (n = 8243) were treated for 5.0 ± 0.4 years with losartan or atenolol based therapy. Associations of serum uric acid with new-onset atrial fibrillation documented by Minnesota coding were assessed by Cox models using serum uric acid and systolic blood pressure as time-varying covariates to take into account changes of serum uric acid related to losartan or diuretic treatment, changes in renal function, and aging. Results: Time-varying serum uric acid was associated with new atrial fibrillation defined by Minnesota code (HR = 1.19 per 16.8 umol/L [1 mg/dL] [95% CIs, 1.12–1.26], P &lt; 0.0001), independent of losartan treatment (HR = 0.75 [95% CIs, 0.61–0.93], P = 0.007), older age (HR = 1.95 per 7.0 years [95% CIs, 1.73–2.20], P &lt; 0.0001), male sex (HR = 1.46 [95% CIs, 1.09–1.94], P = 0.010) and higher Cornell voltage duration product (HR = 1.10 per 1023 msec x mm [95% CIs, 1.01–1.21], P = 0.034). Similar results were obtained in Cox models with serum uric acid levels partitioned according to baseline quartiles and in which atrial fibrillation was defined by physician reports or by both Minnesota coding and physician reports. Conclusions: Thus, we found a strong relationship between time-varying serum uric acid levels during antihypertensive treatment and new-onset atrial fibrillation in elderly patients with left ventricular hypertrophy. Our data suggest that in-treatment serum uric acid is a strong predictor for new onset atrial fibrillation in hypertensive patients, independent of effects of antihypertensive treatment, age, sex, and electrocardiographic left ventricular hypertrophy. Further research is needed to clarify how serum uric acid may provoke atrial fibrillation.

Factors Affecting Patient Adherence to Pharmacological Therapy in Gout Arthritis and Hyperuricemia

Abstract Background: Pharmacological therapy to reduce serum uric acid levels in gouty arthritis and hyperuricemia patients is essential to prevent gout flare and other hyperuricemia-related morbidities. However, only about 50% of gout arthritis patients adhered to their treatment. Knowing the factors influencing adherence to therapy can be used as a reference for health services to improve adherence.Objective: This study aimed to analyze the factors that influenced the patient's adherence to gouty arthritis and hyperuricemia pharmacological therapy.Methods: This was an observational study with a cross-sectional approach. Subjects were the patients in Wuryantoro Community Health Center, Wonogiri Regency, diagnosed with gouty arthritis or hyperuricemia due to a disorder in purine metabolism. Sampling was done by a consecutive sampling method. Questionnaires with the related medical record were used to collect the necessary data. Research variables were knowledge, attitudes and behavior, gender, age, occupation, insurance, distance from residence to health care facilities, and adherence to therapy which was in binary.Results: Sixty-one percent from a total of 41 respondents were found to be non-adherence to pharmacological therapy. Knowledge, attitudes, and behavior towards therapy, educational level, availability of health insurance, and distance to health facilities were significantly correlated to treatment adherence (p &lt; 0.05). Sex, age, and occupation were not correlated to adherence.Conclusion: Factors influencing adherence were knowledge, attitudes and behavior, academic background, insurance, and the distance from residence to health care facilities.