Hyperuricemia: A Biomarker of Renal Hemodynamic Impairment

Evaluating the effectiveness and safety of acupuncture on serum uric acid in asymptomatic hyperuricemia population: a randomized controlled clinical trial study protocol

Background

The clinical dangers of asymptomatic hyperuricemia to human health have become increasingly prominent over the past 20 years. Previous studies have shown the potential benefits of acupuncture on uric acid levels in the body. However, definitive evidence is lacking. Our objective is to evaluate the efficacy and safety of acupuncture on serum uric acid (SUA) in individuals with asymptomatic hyperuricemia.

Methods

This is a randomized, single-blind, sham-controlled trial. A total of 180 eligible patients with asymptomatic hyperuricemia will be recruited at three hospitals in China. Patients will be randomly assigned in a 1:1 ratio to receive 16 sessions of manual acupuncture or sham acupuncture for 8 weeks. Patients will be followed up for 12 weeks. The primary outcome will be the change in SUA levels at week 8 after randomization. Secondary outcomes will include dynamic changes in SUA levels, efficacy rates, proportion of gout flare, body weight, and acute medication intake. The MGH Acupuncture Sensation Scale and adverse events related to acupuncture will be measured after each treatment. A blinding assessment will be performed on patients who receive at least one session of acupuncture. Data analyses will be performed on a full analysis set and a per-protocol set.

Ethics and dissemination

Ethics approval has been obtained from the Clinical Trial Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology (approval no. 2021-S135). Written informed consent will be obtained from enrolled patients. The findings will be disseminated in a peer-reviewed journal.

Clinical trial registration

ClinicalTrials.gov identifier, NCT05406830.

Uric acid en route to gout

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

Design, synthesis and bioactive evaluation of geniposide derivatives for antihyperuricemic and nephroprotective effects

Hyperuricemia is a principal factor mediating gout and kidney damage, and xanthine oxidase (XOD) is a key enzyme in the pathogenesis of hyperuricemia. In this context, a series of geniposide derivatives were designed and synthesized, and antihyperuricemic and nephroprotective effects of all derivatives was evaluated in vitro and in vivo. Compound 2e emerged as the most potent XOD inhibitor, with an IC₅₀ value of 6.67 ± 0.46 µM. Simultaneously, cell viability, ROS generation, and SOD levels assay showed that compound 2e could repair the damage of HKC cells by inhibiting the oxidative stress response. The results of the study indicated compound 2e significantly decreased uric acid levels by inhibiting the XOD activity, and repaired kidney damage by inhibiting the expression of TLR4/TLR2/MyD88/NF-κB and NALP3/ASC/caspase-1 signaling pathways. Enzyme inhibition kinetics suggested that compound 2e functioned via reversible mixed competitive inhibition. Moreover, a molecular docking study was performed to gain insight into the binding mode of compound 2e with XOD. These results suggest that geniposide derivatives were potential to be developed into a novel medicine to reveal healthy benefits in natural prevention and reduction risk of hyperuricemia and kidney damage.

Acupuncture to treat asymptomatic hyperuricemia: A protocol for systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Hyperuricemia (HUA) plays an important role in metabolic syndrome, cardiovascular disease, and kidney disease. HUA without resulting gout is referred to as asymptomatic HUA. The purpose of the present systematic review protocol is to provide methods to assess the effectiveness and safety of acupuncture-based treatment for asymptomatic HUA.

METHODS

To identify randomized controlled trials (RCTs) involving acupuncture-based treatment for asymptomatic HUA, a search will be carried out using the following eight electronic databases: MEDLINE, EMBASE, Cochrane Library, Korea Med, Oriental Medicine Advanced Searching Integrated System, Korean Studies Information Service System, China National Knowledge Infrastructure, and Japanese Institutional Repositories Online. Manual search and email contact with the author will also be conducted if necessary. Studies will be selected based on predefined criteria and summarized data regarding study participants, interventions, control groups, outcome measures, side effects, and risk of bias. No language restrictions will be imposed. Studies that evaluated any type of acupuncture will be eligible for inclusion, and the primary outcome will be the blood uric acid level. The methodological quality of the included RCTs will be assessed using the Cochrane risk of bias tool.

RESULTS

The present study will evaluate the efficacy and safety of acupuncture to treat HUA.

CONCLUSION

Our findings will establish the evidence for acupuncture-based treatment of HUA and will be informative for patients with HUA, clinicians, policy makers, and researchers.

REGISTRATION NUMBER

reviewregistry1054.

Renal Resistive Index of the Main Renal Arteries and Transmitral Flow in Hypertensive Patients

In hypertensive patients, diastolic dysfunction is related to increased resistive index (RI) of parenchymal renal arteries. To determine the existence of a link between RI of the main renal arteries (RRI) and diastolic dysfunction, a group of 127 hypertensive patients, with glomerular filtration rates >50 mL/min (mean estimated glomerular filtration rate: 88.6 ± 15.2 mL/min) and no comorbidities, was studied. RRI and transmitral flow were evaluated using the deceleration time (DT) and E/A ratio. A statistically significant correlation between RRI and DT (>240 ms) was noted (p < 0.001). The RRI cutoff that best discriminated patients with DT >240 ms was 0.675. For each unitary increment of 10 mm in DT, the log-transformed RRI significantly increased by a mean of 0.006 point (p < 0.001). This study revealed the importance of the link between RRI and transmitral DT in addition to the renowned significance of the increase in RI as a cardiovascular risk factor in hypertensive patients without comorbidities.

Predictors of Hyperuricemia after Kidney Transplantation: Association with Graft Function

Background and objectives: In kidney transplant recipients (KTR), hyperuricemia (HU) is a commonly-observed phenomenon, due to calcineurin inhibitors and reduced kidney graft function. Factors predicting HU, and its association with graft function, remains equivocal. Materials and Methods: We conducted a retrospective longitudinal study to assess factors associated with HU in KTR, and to determine risk factors associated with graft function, measured as glomerular filtration rate (GFR). Moreover, GFR > 60 mL/min/1.73 m² was considered normal. HU was defined as a serum uric acid level of > 416 μmol/L (4.70 mg/dL) in men and >357 μmol/L (4.04 mg/dL) in women, or xanthine-oxidase inhibitor use. We built multiple logistic regression models to assess predictors of HU in KTR, as well as the association of demographic, clinical, and biochemical parameters of patients with normal GFR after a three-year follow-up. We investigated the effect modification of this association with HU. Results: There were 144 patients (mean age 46.6 ± 13.9), with 42.4% of them having HU. Predictors of HU in KTR were the presence of cystic diseases (OR = 9.68 (3.13; 29.9)), the use of diuretics (OR = 4.23 (1.51; 11.9)), and the male gender (OR = 2.45 (1.07; 5.56)). Being a younger age, of female gender, with a normal BMI, and the absence of diuretic medications increased the possibility of normal GFR. HU was the effect modifier of the association between demographic, clinical, and biochemical factors and a normal GFR. Conclusions: Factors associated with HU in KTR: Presence of cystic diseases, diuretic use, and male gender. HU was the effect modifier of the association of demographic, clinical, and biochemical factors to GFR.

Prognostic value of hyperuricemia in patients with acute coronary syndrome: A meta-analysis

BACKGROUND

The prognostic significance of elevated circulating uric acid level in patients with acute coronary syndrome (ACS) is conflicting. This meta-analysis aimed to assess the prognostic value of hyperuricemia in patients with ACS.

METHODS

A comprehensive literature search was performed in Pubmed, Embase, VIP, CNKI and WanFang databases up to 16 June 2018. All observational studies that investigated the prognostic value of hyperuricemia in ACS patients were selected. Outcome of interests was major adverse cardiovascular events (MACEs), all-cause mortality or cardiovascular mortality.

RESULTS

A total of nine studies enrolling 8776 ACS patients were included and analysed. ACS patients with hyperuricemia had an increased risk of MACEs (risk ratio [RR]: 1.86; 95% confidence intervals [CI]: 1.47-2.35), all-cause mortality (RR 1.86; 95% CI: 1.49-2.32) and cardiovascular mortality (RR: 1.74; 95% CI: 1.36-2.22) after adjustment for the conventional risk factors. Stratified analysis showed that the prognostic significance of hyperuricemia was consistently observed in each subgroups.

CONCLUSIONS

This meta-analysis suggests that hyperuricemia independently predicts MACEs and death in ACS patients. Determination of uric acid level has potential to improve risk stratification of adverse outcomes in ACS patients.

Production Inhibition and Excretion Promotion of Urate by Fucoidan from Laminaria japonica in Adenine-Induced Hyperuricemic Mice

This work aims to explore the amelioration of fucoidan on adenine-induced hyperuricemia and hepatorental damage. Adenine-induced hyperuricemic mice were administered with fucoidan, allopurinol and vehicle control respectively to compare the effects of the drugs. Serum uric acid, urea nitrogen, hepatorenal functions, activities of hepatic adenosine deaminase (ADA), xanthine oxidase (XOD), renal urate transporter 1 (URAT1) and NF-κB p65 were assessed. As the serum uric acid, urea nitrogen, creatinine, glutamic oxalacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) data demonstrated, the adenine not only mediated hepatorenal function disorders, but also induced hyperuricemia in mice. Meanwhile, activities of hepatic ADA and XOD were markedly augmented by adenine, and the expression of URAT1 was promoted, which was conducive to the reabsorption of urate. However, exposure to fucoidan completely reversed those adenine-induced negative alternations in mice, and the activities of hepatic ADA and XOD were recovered to the normal level. It was obvious that hepatic and renal functions were protected by fucoidan treatment. The expression of URAT1 was returned to normal, resulting in an increase of renal urate excretion and consequent healing of adenine-induced hyperuricemia in mice. Expression and activation of NF-κB p65 was promoted in kidneys of adenine treated mice, but suppressed in kidneys of mice exposed to fucoidan from Laminaria japonica or allopurinol. In conclusion, the fucoidan is a potential therapeutic agent for the treatment of hyperuricemia through dual regulatory roles on inhibition of hepatic metabolism and promotion of renal excretion of urate.

Insulin Resistance in Kidney Disease: Is There a Distinct Role Separate from That of Diabetes or Obesity?

Insulin resistance is a central component of the metabolic dysregulation observed in obesity, which puts one at risk for the development of type 2 diabetes and complications related to diabetes such as chronic kidney disease. Insulin resistance and compensatory hyperinsulinemia place one at risk for other risk factors such as dyslipidemia, hypertension, and proteinuria, e.g., development of kidney disease. Our traditional view of insulin actions focuses on insulin-sensitive tissues such as skeletal muscle, liver, adipose tissue, and the pancreas. However, insulin also has distinct actions in kidney tissue that regulate growth, hypertrophy, as well as microcirculatory and fibrotic pathways which, in turn, impact glomerular filtration, including that governed by tubuloglomerular feedback. However, it is often difficult to discern the distinct effects of excess circulating insulin and impaired insulin actions, as exist in the insulin resistance individual, from the associated effects of obesity or elevated systolic blood pressure on the development and progression of kidney disease over time. Therefore, we review the experimental and clinical evidence for the distinct impact of insulin resistance on kidney function and disease.

Prevalence of hyperuricemia and its related risk factors among preschool children from China

To estimate the prevalence of hyperuricemia and its major risk factors among Chinese preschool children. A cross-sectional survey was carried out in six central urban districts of Tianjin from March to June 2015. A cluster sampling was employed to obtain a random sample of preschool children. A total of 4073 children aged from 3 to 6 years participated in this survey. Logistic regression was used to obtain odds ratios and 95% confidence intervals. The overall mean serum uric acid concentrations was 243.0 ± 53.2 μmol/L, corresponding to a mean concentrations of 247.3 ± 53.7 μmol/L among boys and 238.3 ± 52.4 μmol/L among girls. The overall prevalence of serum uric acid ≥ 310 μmol/L among children was 10.1%. Boys, obesity, diastolic blood pressure, and serum triglyceride concentrations were associated with the increased risk of hyperuricemia in univariable models, although the statistically significant association between diastolic blood pressure, serum triglyceride concentrations and hyperuricemia disappeared in multivariable models. The prevalence of hyperuricemia among children aged from 3 to 6 years was relatively high. Several metabolic syndrome components were associated with the risk of hyperuricemia.

Hyperuricemia increases the risk of acute kidney injury: a systematic review and meta-analysis

Background

Mounting evidence indicated that the elevated serum uric acid level was associated with an increased risk of acute kidney injury (AKI). Our goal was to systematically evaluate the correlation of serum uric acid (SUA) level and incidence of AKI by longitudinal cohort studies.

Methods

We searched electronic databases and the reference lists of relevant articles. 18 cohort studies with 75,200 patients were analyzed in this random-effect meta-analysis. Hyperuricemia was defined as SUA levels greater than 360-420 μmol/L (6–7 mg/dl), which was various according to different studies. Data including serum uric acid, serum creatinine, and incidence of AKI and hospital mortality were summarized using random-effects meta-analysis.

Results

The hyperuricemia group significantly exerted a higher risk of AKI compared to the controls (odds ratio OR 2.24, 95% CI 1.76-2.86, p < 0.01). Furthermore, there is less difference of the pooled rate of AKI after cardiac surgery between hyperuricemia and control group (34.3% vs 29.7%, OR 1.24, 95% CI 0.96-1.60, p = 0.10), while the rates after PCI were much higher in hyperuricemia group than that in control group (16.0% vs 5.3%, OR 3.24, 95% CI 1.93-5.45, p < 0.01). In addition, there were significant differences in baseline renal function at admission between hyperuricemia and control groups in most of the included studies. The relationship between hyperuricemia and hospital mortality was not significant. The pooled pre-operative SUA levels were higher in AKI group than that in the non-AKI group.

Conclusions

Elevated SUA level showed an increased risk for AKI in patients and measurements of SUA may help identify risks for AKI in these patients.

Acupuncture for serum uric acid in patients with asymptomatic hyperuricemia: A randomized, double-blind, placebo-controlled trial

BACKGROUND

Hyperuricemia (HUA) is the most common disease associated with cardiovascular disease, metabolic syndrome, hypertension, and kidney disease. The objective of the current study was to evaluate the preliminary efficacy, mechanism, and safety of acupuncture on serum uric acid in patients with asymptomatic HUA.

METHODS

A randomized, placebo-controlled trial among 123 patients with asymptomatic HUA was conducted. The acupoints used in the acupuncture group were bilateral Five Shu in Spleen Meridian. Each participant received the intervention once daily for 10 consecutive days. The sham group received the same treatment duration on the same acupoints by the Park Sham Device. All patients underwent measurements of serum or urine creatinine, uric acid, serum lipid profiles, fasting plasma glucose, HbA1c, xanthine oxidase (XOD) and urate-anion exchanger (URAT-1).

RESULTS

At the end of the intervention, the individuals in the acupuncture group were found to have significantly less levels of serum uric acid than those in the sham group [(453±65 vs. 528±81) μmol/L, p<0.01]. Acupuncture was effective on increasing the urine uric acid level, urine pH value and 24-hour urine volume than the sham treatment (p<0.05 for all). Interestingly, acupuncture significantly decreased the level of URAT-1 (p<0.01) but not XOD than that of the sham intervention. The adverse events were that 3 patients experienced severe pain.

CONCLUSIONS

Acupuncture on Five Shu in Spleen Meridian appeared to be safe and efficacious for decreasing serum uric acid in a Chinese HUA patient population. The mechanism might be associated with the decrease level of enzyme URAT-1.

CHINESE CLINICAL TRIAL REGISTRATION

ChiCTR-TRC-13004122.

Uric acid transporters hiding in the intestine

CONTEXT

Hyperuricaemia is known as an abnormally increased uric acid level in the blood. Although it was observed many years ago, since uric acid excretion via the intestine pathway accounted for approximately one-third of total elimination of uric acid, the molecular mechanism of 'extra-renal excretion' was poorly understood until the finding of uric acid transporters.

OBJECTIVE

The objective of this study was to gather all information related to uric acid transporters in the intestine and present this information as a comprehensive and systematic review article.

METHODS

A literature search was performed from various databases (e.g., Medline, Science Direct, Springer Link, etc.). The key terms included uric acid, transporter and intestine. The period for the search is from the 1950s to the present. The bibliographies of papers relating to the review subject were also searched for further relevant references.

RESULTS

The uric acid transporters identified in the intestine are discussed in this review. The solute carrier (SLC) transporters include GLUT9, MCT9, NPT4, NPT homolog (NPT5) and OAT10. The ATP binding cassette (ABC) transporters include ABCG2 (BCRP), MRP2 and MRP4. Bacterial transporter YgfU is a low-affinity and high-capacity transporter for uric acid.

CONCLUSION

The present review may be helpful for further our understanding of hyperuricaemia and be of value in designing future studies on novel therapeutic pathways.

Serum uric acid as a marker of microvascular damage in systemic sclerosis patients

BACKGROUND

Microvascular damage of skin and internal organs is a hallmark of systemic sclerosis (SSc). Serum uric acid (UA) represents a marker of inflammation and endothelial dysfunction. The aims of this study were to evaluate the correlation between serum UA and intrarenal arterial stiffness evaluated by Doppler ultrasound in SSc patients with normal renal function. We also evaluated the correlation between serum UA and other clinical variables of the disease.

METHODS

Forty-five SSc patients underwent clinical assessment, Doppler ultrasound of intrarenal arteries with evaluation of resistive index (RI), pulsatile index (PI), and systolic/diastolic ratio (S/D), echocardiography with systolic pulmonary artery pressure (PAPs), baseline pulmonary function tests, and nailfold videocapillaroscopy (NVC). In all patients serum UA was measured.

RESULTS

The serum UA showed a significant positive correlation with sCr (r=0.33, p<0.0001) and PAPs (r=0.38, p<0.01) >and negative correlation with CKD-EPI (r=-0.35, p<0.01). The mean value of serum UA increased with severity of NVC damage. Using this cut-off value of 4.7mg/dl, the mean value of Doppler indices of intrarenal stiffness is significantly different (p<0.05) in SSc patients with low normal or high normal serum UA.

CONCLUSIONS

Serum UA concentration is higher in patients with high microvascular damage than in patients with low microvascular damage. These preliminary data must be confirmed in large prospective studies.

Uric Acid for Cardiovascular Risk: Dr. Jekyll or Mr. Hide?

Uric acid (UA) is a potent endogenous antioxidant. However, high concentrations of this molecule have been associated with cardiovascular disease (CVD) and renal dysfunction, involving mechanisms that include oxidative stress, inflammatory processes, and endothelial injury. Experimental and in vitro results suggest that this biomarker behaves like other antioxidants, which can shift from the physiological antioxidant action to a pro-oxidizing effect according to their level and to microenvironment conditions. However, data on patients (general population or CAD cohorts) are controversial, so the debate on the role of hyperuricemia as a causative factor for CVD is still ongoing. Increasing evidence indicates UA as more meaningful to assess CVD in women, even though this aspect needs deeper investigation. It will be important to identify thresholds responsible for UA “biological shift” from protective to harmful effects in different pathological conditions, and according to possible gender-related differences. In any case, UA is a low-tech and inexpensive biomarker, generally performed at patient’s hospitalization and, therefore, easily accessible information for clinicians. For these reasons, UA might represent a useful additive tool as much as a CV risk marker. Thus, in view of available evidence, progressive UA elevation with levels higher than 6 mg/dL could be considered an “alarm” for increased CV risk.

The Association Between Hyperuricemia and Hematological Indicators in a Chinese Adult Population

The aim of this study was to explore the relationship between hyperuricemia and hematological indicators. Five hundred twenty-two male and 255 female subjects (18-90 years old) were recruited in the study. The level of serum uric acid (SUA), total white blood cell (WBC) count, red blood cell (RBC) count, hemoglobin, hematocrit, and platelet count was measured, computed, and analyzed. Pearson correlation coefficients, Student t-tests, multivariate linear regression models, and multivariate logistic regression models were performed to analyze the results.For men, WBC count (r = 0.13, P < 0.01), RBC count (r = 0.15, P < 0.001), and hemoglobin (r = 0.11, P < 0.05) were significantly correlated with SUA. For women, WBC count (r = 0.24, P < 0.001), RBC count (r = 0.31, P < 0.001), hemoglobin (r = 0.31, P < 0.001), and hematocrit (r = 0.29, P < 0.001) were significantly correlated with SUA. For men, WBC (P < 0.01) and RBC (P < 0.05) counts were significantly higher in patients with hyperuricemia than in normal subjects. For men, after adjustment for confounding factors, those in the fourth quartiles of WBC counts had 1.66-fold increased odds of hyperuricemia as compared with those in the reference group. For women, after adjustment, those in the second to fourth quartiles of WBC count, RBC count, hemoglobin, and hematocrit had increased the odds of hyperuricemia as compared with those in the reference groups. Our study showed significant relations between the level of SUA and WBC count, RBC count, hemoglobin, and hematocrit, which could be important biological markers of hyperuricemia.