The Impact of Uric Acid and Hyperuricemia on Cardiovascular and Renal Systems

The relationship between serum uric acid and gastrointestinal bleeding in peritoneal dialysis patients: a propensity score analysis

PURPOSE

Gastrointestinal bleeding is an important gastrointestinal complication among peritoneal dialysis patients and correlated with a higher risk of mortality. Increased uric acid levels are a significant complication for peritoneal dialysis patients and have been associated with an increased risk of hemorrhagic stroke. The objective of the present study was to investigate the relationship between serum uric acid levels and gastrointestinal bleeding in peritoneal dialysis patients.

METHODS

A total of 2498 peritoneal dialysis patients were recruited. Based on the optimal uric acid cutoff value, two groups of patients were divided. We constructed a propensity-score-matched population of 1762 patients by matching sex, age, and body mass index. Survival outcomes between the two groups were compared using adjusted Kaplan-Meier curves. We constructed the restricted cubic splines regression to assess the correlation between levels of uric acid and gastrointestinal bleeding. A multivariate Cox proportional hazards regression was performed to test whether higher levels of uric acid are an independent risk factor for gastrointestinal bleeding. We performed a forest plot to show interaction effects in different subgroups.

RESULTS

According to restricted cubic splines regression, uric acid levels were positively correlated with the risk of gastrointestinal bleeding events. After adjusted different confounding factors, patients with high levels of uric acid were prone to experience gastrointestinal bleeding (HR 1.868, 95%CI 1.001-3.486). In subgroups, the interaction between higher levels of uric acid and utilizing proton pump inhibitors was significant (P for interaction = 0.034). Further research found that taking proton pump inhibitors could decrease the risk of gastrointestinal bleeding in peritoneal dialysis patients accompanied high levels of uric acid.

CONCLUSION

The baseline high levels of uric acid are an independent risk factor for gastrointestinal bleeding in patients undergoing peritoneal dialysis.

Effects of hydrogen-rich water on blood uric acid in patients with hyperuricemia: A randomized placebo-controlled trial

Background

Consumption of hydrogen-rich water (HRW) has been shown to have anti-inflammatory and metabolic-modulatory benefits.

Objective

A randomized, placebo-controlled trial was conducted to assess the potential blood uric acid-lowering effects of HRW consumption with different doses (low and high doses) and duration (4 and 8 weeks) in patients with hyperuricemia.

Methods

The Placebo group consumed three bottles of ordinary drinking water (330 mL per bottle), the Low-HRW group consumed two bottles of HRW (330 mL per bottle, H2 ≥ 4.66 mg/L) and a bottle of ordinary water, and the High-HRW group consumed three bottles of HRW daily for 8 weeks. The primary outcome was the blood uric acid levels following different time points (4 and 8 weeks) compared to baseline.

Results

A total of 100 participants completed the entire trial (32 in Placebo, 35 in Low-HRW, and 33 in High-HRW groups). The high-dose of HRW was more effective than low-dose HRW in controlling blood uric acid. Following an 8-week period, the High-HRW group exhibited a significant reduction in blood uric acid levels compared to the baseline (488.2 ± 54.1 μmol/L to 446.8 ± 57.1 μmol/L, P < 0.05).

Conclusion

As a rather safe agent, the prolonged consumption of HRW may be feasible in the management of hyperuricemia.

Clinical trial registration

chictr.org.cn, identifier ChiCTR2200066369.

Hyperuricemia and its related diseases: mechanisms and advances in therapy

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

Analysis of risk factors for changes of renal artery resistance indexes in gout patients by ultrasound colour Doppler

Objectives

Gout may disturb renal hemodynamics by promoting uric acid deposition; however, this relationship has not been elucidated with adequate clinical evidence. In this study, we measured the renal artery resistance index (ARI) in patients with gout to identify the risk factors and establish predictive models for elevated renal ARI in these patients.

Methods

Renal artery ultrasound examination was performed in 235 primary gout patients and 50 healthy controls (HCs); subsequently, their renal interlobar ARI (RIARI), renal segmental ARI (RSARI) and overall intrarenal ARI (OIARI) were recorded. Each ARI > 0.7 was considered elevated.

Results

RIARI, RSARI and OIARI were higher in patients with gout than in HCs (all P < 0.001). Nineteen (8.1%), 24 (10.2%) and 18 (7.7%) patients had elevated RIARI, RSARI and OIARI scores, respectively. Multivariate logistic regression analyses disclosed that: age ≥ 60 years (P = 0.000), abnormal beta2 microglobulin (β2MG) (P = 0.028), and abnormal high-density lipoprotein cholesterol (HDLC) (P = 0.030) were independently associated with elevated RIARI; age ≥ 60 years (P = 0.000), and abnormal β2MG (P = 0.013) were independently related to elevated RSARI; abnormal total protein (TP) (P = 0.014) were independently linked with elevated OIARI in gout patients. Consequently, predictive models for elevated ARI were established using nomograms based on the aforementioned independent risk factors, which showed a satisfactory value for estimating elevated RIARI [area under the curve (AUC):0.929], RSARI (AUC: 0.926) and OIARI (AUC: 0.660) in patients with gout, as validated by receiver operating characteristic curves.

Conclusion

Renal ARI were elevated in patients with gout, whose independent risk factors included older age and abnormal β2MG, HDLC and TP levels.

Hesperitin-Copper(II) Complex Regulates the NLRP3 Pathway and Attenuates Hyperuricemia and Renal Inflammation

BACKGROUND

Hyperuricaemia (HUA) is a disorder of purine metabolism in the body. We previously synthesized a hesperitin (Hsp)-Cu(II) complex and found that the complex possessed strong uric acid (UA)-reducing activity in vitro. In this study we further explored the complex's UA-lowering and nephroprotective effects in vivo.

METHODS

A mouse with HUA was used to investigate the complex's hypouricemic and nephroprotective effects via biochemical analysis, RT-PCR, and Western blot.

RESULTS

Hsp-Cu(II) complex markedly decreased the serum UA level and restored kidney tissue damage to normal in HUA mice. Meanwhile, the complex inhibited liver adenosine deaminase (ADA) and xanthine oxidase (XO) activities to reduce UA synthesis and modulated the protein expression of urate transporters to promote UA excretion. Hsp-Cu(II) treatment significantly suppressed oxidative stress and inflammatory in the kidney, reduced the contents of cytokines and inhibited the activation of the nucleotide-binding oligomerization domain (NOD)-like receptor thermal protein domain associated protein 3 (NLRP3) inflammatory pathway.

CONCLUSIONS

Hsp-Cu(II) complex reduced serum UA and protected kidneys from renal inflammatory damage and oxidative stress by modulating the NLRP3 pathway. Hsp-Cu(II) complex may be a promising dietary supplement or nutraceutical for the therapy of hyperuricemia.

Prediction of hyperuricemia in people taking low-dose aspirin using a machine learning algorithm: a cross-sectional study of the National Health and Nutrition Examination Survey

Background: Hyperuricemia is a serious health problem related to not only gout but also cardiovascular diseases (CVDs). Low-dose aspirin was reported to inhibit uric acid excretion, which leads to hyperuricemia. To decrease hyperuricemia-related CVD, this study aimed to identify the risk of hyperuricemia in people taking aspirin. Method: The original data of this cross-sectional study were obtained from the National Health and Nutrition Examination Survey between 2011 and 2018. Participants who filled in the "Preventive Aspirin Use" questionnaire with a positive answer were included in the analysis. Six machine learning algorithms were screened, and eXtreme Gradient Boosting (XGBoost) was employed to establish a model to predict the risk of hyperuricemia. Results: A total of 805 participants were enrolled in the final analysis, of which 190 participants had hyperuricemia. The participants were divided into a training set and testing set at a ratio of 8:2. The area under the curve for the training set was 0.864 and for the testing set was 0.811. The SHapley Additive exPlanations (SHAP) method was used to evaluate the performances of the modeling. Based on the SHAP results, the feature ranking interpretation showed that the estimated glomerular filtration rate, body mass index, and waist circumference were the three most important features for hyperuricemia in individuals taking aspirin. In addition, triglyceride, hypertension, total cholesterol, high-density lipoprotein, low-density lipoprotein, age, race, and smoking were also correlated with the development of hyperuricemia. Conclusion: A predictive model established by XGBoost algorithms can potentially help clinicians make an early detection of hyperuricemia risk in people taking low-dose aspirin.

New perspective on first-trimester serum uric acid level in predicting the risk of gestational diabetes mellitus

This study aimed to investigate the correlation between serum uric acid (UA) and gestational diabetes mellitus (GDM) during the first trimester and provide a new perspective for the prevention and treatment of GDM. Based on the diagnostic criteria of gestational diabetes of the International Association of Diabetes and Pregnancy Study Groups, 1744 and 4256 patients were enrolled in the GDM and normal glucose tolerance (NGT) groups. Four groups were constituted based on the quartile of first-trimester serum UA (UA) level, and the differences in each indicator between groups were compared. Logistic regression was used to analyze the effects of UA level on GDM risk. The rate of GDM in the UA quartile changed from low to high. Significant differences were also observed in fasting plasma glucose level, 1 h post glucose and 2 h post glucose levels, in all the groups (P < 0.05), which increased with the UA level. UA level were independent risk factors for GDM. The best threshold of GDM predicted by the first-trimester UA level was 226.55 μmol/L. The first-trimester UA level in patients with GDM was relatively higher and was an independent risk factor for GDM.

Association Between Serum Uric Acid Levels and Neoatherosclerosis

Neoatherosclerosis is a major cause of stent failure after percutaneous coronary intervention. Metabolism such as hyperuricemia is associated with in-stent restenosis (ISR). However, the association between serum uric acid (sUA) levels and in-stent neoatherosclerosis (ISNA) has never been validated.A total of 216 patients with 220 ISR lesions who had undergone optical coherence tomography (OCT) of culprit stents were included in this study. According to their sUA levels, eligible patients were divided into two groups [normal-sUA group: sUA < 7 mg/dL, n = 126, and high-sUA group: sUA ≥ 7 mg/dL, n = 90]. OCT findings were analyzed and compared between the normal- and high-sUA groups.The incidence of ISNA (63.0% versus 43.0%, P = 0.004) was significantly higher in the high-sUA group than in the normal-sUA group. Lipid plaques (66.3% versus 43.0%, P < 0.001) and thin-cap fibroatheroma (38.0% versus 18.0%, P = 0.001) were observed more frequently in the restenotic tissue structure in patients in the high-sUA group than in those in the normal-sUA group. Meanwhile, univariate (OR: 1.208, 95% CI: 1.037-1.407; P = 0.015) and multivariate (OR: 1.254, 95% CI: 1.048-1.501; P = 0.013) logistic regression analyses indicated that sUA levels were an independent risk factor for ISNA after adjusting for relevant risk factors.The high-sUA levels were an independent risk factor for the occurrence of neoatherosclerosis in patients with ISR via OCT.

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

Background

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.

Methodology

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.

Results

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.

Conclusion

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.

Characterizing the specific mechanism of series processed Coptidis Rhizoma by multi-organ metabolomics combined with network pharmacology and molecular docking

BACKGROUND

After being processed with different excipients, the clinical application of Coptidis Rhizoma (CR) is differentially investigated. However, the underlying mechanism and material basis are not clear, and there is a lack of attention to the collaborative working mode of herbal medicine during exploration.

PURPOSE

To characterize the specific mechanism of wine/zingiberis rhizoma recens/euodiae fructus processed CR (wCR/zCR/eCR) and to investigate the role of excipients during processing.

METHODS

The multi-organ metabolomics approach was employed to explore the target organs of wCR/zCR/eCR and multiple pathways being triggered in each organ. The tissue distribution of CR and wCR/zCR/eCR components was compared to indicate the material basis of efficacy change after processing. Further, the network pharmacology study coupled with experimental validation was conducted to support metabolomic research and predicted active ingredients and core targets, and the molecular docking coupled with binding test was performed to identify the binding between active ingredient and core target.

RESULTS

The multi-organ metabolomics and network pharmacology study elucidated the intervening effect of wCR on heart/lung, zCR on stomach/colon, and eCR on liver/colon/stomach. Combined with molecular docking, binding test and tissue distribution studies, the specific mechanism was as follows: the wine made iso-quinoline alkaloids in CR more likely to accumulate in heart/lung, thus triggering the core targets of PTGS2, NOS2, ESR1 and SLC6A4 in heart/lung, and thereby highlighting the detoxifying and cardiopulmonary protective effect of wCR. The zingiberis rhizoma recens and euodiae fructus made organic acids in CR more likely to accumulate in stomach/colon and liver/colon/stomach respectively, thus triggering the core targets of ACTB, TNF and PRKCA in stomach/colon, the core targets of ACTB, TNF, PRKCA and GPT in stomach/colon/liver, and thereby highlighting the improving effect of zCR/eCR on digestive function.

CONCLUSION

Iso-quinoline alkaloids were the material basis of CR for anti-inflammation, and organic acids were mainly responsible for regulating gastrointestinal function. Due to the influence of excipients on the accumulation tendency of CR components, the differentially highlighted application of wCR/zCR/eCR was achieved. These findings propose a novel strategy for processing mechanism research.

U-shaped association of serum uric acid with cardiovascular disease risk scores and the modifying role of sex among Chinese adults

BACKGROUND AND AIMS

Serum uric acid (SUA) is involved in the development of cardiovascular disease (CVD). However, information on the dose-response relationship between SUA and CVD is limited in the Chinese population. This study aimed to investigate the potential nonlinear dose-response association of SUA with CVD risk in a Chinese population and to explore the effect of sex on these associations.

METHODS AND RESULTS

Cross-sectional data, from 6252 Chinese adults aged 30-74 years who participated in the China Health and Nutrition Survey 2009, were stratified by SUA deciles. The 10-year risk of CVD was determined using the Framingham risk score. A restricted cubic spline (RCS) was incorporated into the logistic models to assess the nonlinear relationship between SUA and CVD. Among the participants, 65%, 20%, and 15% had low, moderate, and high 10-year CVD risks, respectively. Compared with the reference SUA strata of 225 to <249 μmol/L, CVD risk was significantly increased at SUA ≥294 μmol/L, with adjusted ORs ranging from 2.39 (1.33-4.33) to 4.25 (2.37-7.65). An increasingly higher nonsignificant CVD risk was found at SUA <225 μmol/L and showed a nonlinear U-shaped association. In the fitted RCS model, an approximate U-shaped association between SUA and CVD risk scores was found in women, but this significant nonlinear relationship was not found in men.

CONCLUSION

This study showed that both lower and higher SUA levels were associated with a higher 10-year CVD risk among Chinese adults, forming a U-shaped relationship, and this pattern was particularly pronounced for women.

Purine Metabolism Dysfunctions: Experimental Methods of Detection and Diagnostic Potential

Purines, such as adenine and guanine, perform several important functions in the cell. They are found in nucleic acids; are structural components of some coenzymes, including NADH and coenzyme A; and have a crucial role in the modulation of energy metabolism and signal transduction. Moreover, purines have been shown to play an important role in the physiology of platelets, muscles, and neurotransmission. All cells require a balanced number of purines for growth, proliferation, and survival. Under physiological conditions, enzymes involved in purines metabolism maintain a balanced ratio between their synthesis and degradation in the cell. In humans, the final product of purine catabolism is uric acid, while most other mammals possess the enzyme uricase that converts uric acid to allantoin, which can be easily eliminated with urine. During the last decades, hyperuricemia has been associated with a number of human extra-articular diseases (in particular, the cardiovascular ones) and their clinical severity. In this review, we go through the methods of investigation of purine metabolism dysfunctions, looking at the functionality of xanthine oxidoreductase and the formation of catabolites in urine and saliva. Finally, we discuss how these molecules can be used as markers of oxidative stress.

Potential anti-gout properties of Wuwei Shexiang pills based on network pharmacology and pharmacological verification

ETHNOPHARMACOLOGICAL RELEVANCE

Wuwei Shexiang Pills (WWSX), a classic Tibetan medicine, consists of Chebulae Fructus (removed pit), Aucklandiae Radix, Moschus, Aconiti Fiavi Radix, and Acori Calami Rhizoma. It is used clinically in China to treat joint pain, swelling and other symptoms, and has the function of dispelling wind and relieving pain. However, to date, the mechanism of how it works against gout is still unclear.

AIMS OF THE STUDY

Using network pharmacology, molecular docking and pharmacological verification to explore the potential anti-gout properties of WWSX.

MATERIALS AND METHODS

With the use of UPLC-Q/TOF-MS, the main components of WWSX were obtained and screened for potential anti-inflammatory components by network pharmacology and molecular docking. The anti-inflammatory activity of the components screened from WWSX was also tested by in vitro assays. The anti-gout mechanism of WWSX was predicted by network pharmacology, and the pharmacological validation experiments using gouty arthritis model and mouse air pouch model were used to explore the multifaceted mechanism of WWSX to modify gout.

RESULT

Thirty-eight active ingredients were obtained from the UPLC-Q/TOF-MS detection. The network pharmacology and molecular docking analysis showed that 104 co-targets were participated in the treatment of gout, and the main signaling pathways involved were NOD-like receptor pathway, NF-κB pathway and MAPK pathway. Pharmacological evaluation showed that WWSX could significantly improve gout in gouty arthritis models and mouse air pouch models by modulating the above pathways.

CONCLUSION

This work has predicted and validated the anti-inflammatory material basis and predicted the anti-gout mechanism of WWSX which was verified by network pharmacology, molecular docking and in vitro cellular studies. The results reveal the mechanism of WWSX in the treatment of gout and provide a theoretical basis for its clinical application.

Lactobacillus acidophilus Fermented Dandelion Improves Hyperuricemia and Regulates Gut Microbiota

Foodborne prevention and treatment of hyperuricemia (HUA) has received widespread attention. Lactic acid bacteria (LAB) can improve intestinal function, while traditional medicine dandelion has the functions of detoxification and detumescence. Whether LAB fermented dandelion has any effects on HUA and the underlying mechanism is not clear. To address these questions, Lactobacillus acidophilus was selected or maximal xanthine oxidase activity. The effect of Lactobacillus acidophilus fermented dandelion (LAFD) on uric acid metabolism was evaluated by the HUA mouse model. Expression levels of UA, BUN, CRE, XOD, and inflammatory factors in serum were detected. Paraffin sections and staining were used to observe the kidney and small intestine, and mRNA expression of GLUT9, URAT1, OAT1, and ABCG2 related to uric acid metabolism were investigated. Furthermore, the intestinal flora was studied by contents of the cecum and high throughput 16S rRNA sequencing. The results showed that LAFD had a significant inhibitory effect on XOD in vitro (p < 0.01). LAFD could reduce the levels of UA, BUN, CRE, XOD, IL-1 β, IL-6, and TNF- α in serum (p < 0.05), thus inhibiting inflammatory reaction, and reducing UA by decreasing the mRNA expression of GLUT9, URAT1 in kidney and increasing the mRNA expression of OAT1 and ABCG2 in kidney and small intestine (p < 0.05). In addition, the 16S rRNA gene sequencing analysis demonstrated that LAFD treatment can help restore the imbalance of the intestinal microbial ecosystem and reverse the changes in Bacterodietes/Firmicutes, Muribaculaceae, Lachnospiraceae in mice with HUA. It is suggested that the mechanism of LAFD in treating HUA may be related to the regulation of the mRNA expressions of GLUT9, URAT1, OAT1, and ABCG2 in the kidney and small intestine, as well as the regulation of intestinal flora, which provides the experimental basis for the development of new plant fermented products.

Associations between long-term exposure to ambient fine particulate pollution with the decline of kidney function and hyperuricemia: a longitudinal cohort study

Evidence of associations between ambient fine particulate matter (PM_2.5) and risks of decline of kidney function and hyperuricemia is limited. We aimed to investigate the associations between long-term exposure to PM_2.5 with decline of kidney function and hyperuricemia in China. We conducted a two-stage study based on China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2015. Cox proportional hazard regression models and restricted cubic splines were used to evaluate the associations of PM_2.5 with risks of decline of kidney function and hyperuricemia. Latent class trajectory models (LCTM) were used to identify trajectories of PM_2.5 from 2011 to 2015 in the sensitivity analysis. A total of 9760 participants were included in baseline analysis, and 5902 participants were in follow-up analysis. PM_2.5 was associated with the risks of decline of kidney function [hazard ratio (HR): 2.14; 95% confidence interval (CI): (1.03, 4.44)] and hyperuricemia [HR 1.40 (95% CI: 1.10, 1.79)] in the second quartile group versus the lowest quartile group of PM_2.5. We also observed nonlinear relationships between PM_2.5 and the risks of the decline of kidney function and hyperuricemia (P_non-linear < 0.001). In sensitivity analysis, four trajectory groups were identified. "Maintaining a high PM_2.5" [odds ratio (OR): 2.20; 95%CI: (1.78, 2.73)] and "moderately high starting PM_2.5 then steadily decreased" [OR (95%CI): 5.15 (1.55, 16.13)] were associated with hyperuricemia risk, using "low starting PM_2.5 then steadily decreased" trajectory as reference. In conclusion, improved air quality is essential for prevention of decline of kidney function and hyperuricemia.

Citrus Bergamia and Cynara Cardunculus Reduce Serum Uric Acid in Individuals with Non-Alcoholic Fatty Liver Disease

Background and Objectives: Hyperuricemia and liver steatosis are risk factors for cardiovascular diseases and mortality. The use of natural compounds could be a safe and effective alternative to drugs for the treatment of fatty liver and hyperuricemia. Polyphenolic fraction of Citrus Bergamia in association with the extract of Cynara Cardunculus, as nutraceutical, is able to reduce body weight, hepatic steatosis and markers of oxidative stress. Then, we performed a secondary analysis of a double-blind placebo-controlled trial to examine the effects of this nutraceutical on serum uric acid levels in adults with fatty liver. Materials and Methods: The study included 94 individuals with hepatic steatosis. For six weeks, the intervention group was given a nutraceutical (300 mg/day) comprising a Bergamot polyphenol fraction and Cynara Cardunculus extract. The control group received a daily pill of placebo. Serum uric acid, lipids, glucose and anthropometric parameters were assessed at baseline and after 6 weeks. Results: We found a greater reduction in serum uric acid in the participants taking the nutraceutical rather than placebo (−0.1 ± 0.7 mg/dL vs. 0.3 ± 0.7 mg/dL, p = 0.004), and especially in those with moderate/severe hepatic steatosis also after adjustment for confounding variables. In addition, we analysed the two groups according to tertiles of uric acid concentration. Among participants taking the nutraceutical, we found in those with the highest baseline serum uric acid (>5.4 mg/dL) the greater reduction compared to the lowest baseline uric acid (−7.8% vs. +4.9%; adjusted p = 0.04). The stepwise multivariable analysis confirmed the association between the absolute serum uric acid change and nutraceutical treatment (B = −0.43; p = 0.004). Conclusions: A nutraceutical containing bioactive components from bergamot and wild cardoon reduced serum uric acid during 6 weeks in adults with fatty liver. Future investigations are needed to evaluate the efficacy of this nutraceutical in the treatment of hyperuricaemia.

Correlation Between Serum Uric Acid Levels and Coronary Plaque Characteristics on Optical Coherence Tomography

Elevated serum uric acid (sUA) is associated with increasing risk of coronary heart disease (CHD). However, existing research is limited by potential confounders. Herein, our study aims to probe the association between sUA levels and the morphological characteristics of coronary plaque by a propensity score matching (PSM) analysis.All 420 patients with CHD who had undergone optical coherence tomography of culprit lesions were included. Eligible patients were assigned into 2 groups according to sUA level: high-sUA group (sUA ≥ 6.0 mg/dL) and low-sUA group (sUA < 6.0 mg/dL). PSM was applied to control the balance of baseline characteristics.After PSM, a total of 112 patients were included in our study (56 in each group). The high-sUA group showed a higher prevalence of TCFA (35.7% versus 16.1%, P = 0.03) and macrophage infiltration (33.9% versus 14.3%, P = 0.026) compared with the low-sUA group. Plaques in the high-sUA group had a wider maximum lipid arc (166.51° (115.77°, 224.14°) versus 142.29° (93.95°, 169.06°), P = 0.048), longer calcification length (6.77 (3.90, 20.55) mm versus 4.20 (1.95, 7.45) mm, P = 0.040), and thinner minimum fibrous cap thickness (43.81 (28.17, 62.26) μm versus 92.57 (46.25, 135.37) μm, P = 0.003). Correlation analysis indicated that the sUA value was inversely associated with the minimum fibrous cap thickness (r = -0.332, P = 0.015) and positively associated with the maximum lipid arc (r = 0.399, P = 0.003), average lipid arc (r = 0.347, P = 0.011), and calcification length (r = 0.386, P = 0.006).The relationship between high-sUA levels and typical vulnerable features of plaques persisted after balancing the traditional risk factors.

Folic acid and zinc improve hyperuricemia by altering the gut microbiota of rats with high-purine diet-induced hyperuricemia

A high-purine diet can cause hyperuricemia and destroy the microbial composition of the gut microbiota. Both folic acid and zinc significantly reduce uric acid levels and alleviate hyperuricemia. However, whether the underlying mechanisms are associated with the regulation of the gut microbiota remain unknown. To explore alterations of the gut microbiota related to folic acid and zinc treatment in rats with hyperuricemia in our study. A hyperuricemic rat model was established with a high-purine diet. The effects of folic acid and zinc on uric acid levels were evaluated. Alterations of the gut microbiota related to hyperuricemia and the treatments were evaluated by sequencing using the Illumina MiSeq system. The results demonstrated that uric acid levels dropped observably, and the activities of adenosine deaminase (ADA) and xanthine oxidase (XOD) were downregulated after folic acid or zinc intervention. 16S rRNA gene sequencing-based gut microbiota analysis revealed that folic acid and zinc enhanced the abundance of probiotic bacteria and reduced that of pathogenic bacteria, thus improving intestinal barrier function. PICRUST analysis indicated that folic acid and zinc restored gut microbiota metabolism. These findings indicate that folic acid and zinc ameliorate hyperuricemia by inhibiting uric acid biosynthesis and stimulating uric acid excretion by modulating the gut microbiota. Thus, folic acid and zinc may be new and safe therapeutic agents to improve hyperuricemia.

Are the levels of uric acid associated with biometeorological conditions?

Hyperuricemia is an independent risk factor for renal and cardiovascular diseases and is closely associated with gout episodes. It is caused, inter alia, by nutritional habits and genetic factors, and also displays seasonal variability conditioned by meteorological factors. The impact of meteorological factors, including both cold and heat stress, on the human physiology is presented based on the Universal Thermal Climate Index (UTCI) - a biometeorological index derived from an analysis of human thermal balance. The aim of our study was to establish whether seasonal variations significantly affect routinely measured urine acid (UA) levels and could eventually support the clinical decision making process, as well as assessing whether UTCI values are correlated with UA levels in blood serum. This work presents a retrospective epidemiological study of data collected in Olsztyn (Poland). Study material comprised 54,536 results of ambulatory tests measuring UA levels, performed during the period 2016-2019. The analysis concerned correlations between UA and the ages of female and male subjects as well as existing biometeorological conditions as represented by UTCI values in an annual cycle. UA levels in females were found to be lower (4.94 ± 1.37 SD) as compared to those of males (6.13 ± 1.43 SD) and demonstrated a strong positive correlation with age. UA values differed significantly (p < 0.05) on days characterized by cold stress and heat stress, for the oldest age group. UA levels were found to differ depending on the season, but these relationships were not statistically significant, except for significantly higher UA levels in females in autumn (p < 0.001). However, there was an evident difference in population UA levels under cold stress conditions (lower) and heat stress conditions (higher) in the elderly. The UTCI is an adequate predictor of population variations in UA levels since it takes into account the variability of local meteorological conditions.

Serum uric acid levels threshold for mortality in diabetic individuals: The URic acid Right for heArt Health (URRAH) project

BACKGROUND AND AIM

The URRAH (URic acid Right for heArt Health) Study has identified cut-off values of serum uric acid (SUA) predictive of total mortality at 4.7 mg/dl, and cardiovascular (CV) mortality at 5.6 mg/dl. Our aim was to validate these SUA thresholds in people with diabetes.

METHODS AND RESULTS

The URRAH subpopulation of people with diabetes was studied. All-cause and CV deaths were evaluated at the end of follow-up. A total of 2570 diabetic subjects were studied. During a median follow-up of 107 months, 744 deaths occurred. In the multivariate Cox regression analyses adjusted for several confounders, subjects with SUA ≥5.6 mg/dl had higher risk of total (HR: 1.23, 95%CI: 1.04-1.47) and CV mortality (HR:1.31, 95%CI:1.03-1.66), than those with SUA <5.6 mg/dl. Increased all-cause mortality risk was shown in participants with SUA ≥4.7 mg/dl vs SUA below 4.7 mg/dl, but not statistically significant after adjustment for all confounders.

CONCLUSIONS

SUA thresholds previously proposed by the URRAH study group are predictive of total and CV mortality also in people with diabetes. The threshold of 5.6 mg/dl can predict both total and CV mortality, and so is candidate to be a clinical cut-off for the definition of hyperuricemia in patients with diabetes.