Hypertension, its treatment, hyperuricaemia and gout

Associations of oxidative balance score with hyperuricemia and gout among American adults: a population-based study

Objective

The current study aimed to assess the relationships between oxidative balance score (OBS) and OBS subclasses (dietary and lifestyle OBS) with risks of hyperuricemia (HUA) and gout among American adults.

Methods

Participants in the National Health and Nutrition Examination Survey from 2007 to 2018 were initially recruited and then the final sample was restricted to adults without missing values about serum uric acid, gout, OBS, and covariates. Rao-Scott adjusted chi-square test and analysis of variance were utilized to compare the baseline characteristics in adults of different quartiles of OBS, while the weighted stepped logistic regression models were used to explore the associations of overall, dietary, and lifestyle OBS with the risks of HUA and gout. Weighted restricted cubic spline analyses were conducted to explore the nonlinear dose-response associations.

Results

The final sample consisted of 22,705 participants aged 20 years and older, which was representative of approximately 197.3 million non-institutionalized American adults. HUA and gout prevalence decreased with OBS quartiles. Compared with adults in the first quartile of OBS, those in the second (OR: 0.85, 95% CI: 0.72-0.99), third (OR: 0.71, 95% CI: 0.58-0.85), and fourth (OR: 0.48, 95% CI: 0.38-0.61) quartiles of OBS had reduced risks of hyperuricemia. Similarly, adults in the second (OR: 0.70, 95% CI: 0.51-0.97) quartile of OBS was associated with lower gout risk in comparison to adults in the lowest quartile. Regarding OBS subclasses, dietary and lifestyle OBS were both negatively correlated with the risk of HUA, and only higher lifestyle OBS was significantly associated with lower gout risk. Furthermore, the subgroup analyses and interaction effects also substantiated similar effects. Significant nonlinear dose-response relationships were observed between overall, dietary, and lifestyle OBS with HUA risk as well as that of lifestyle OBS with gout risk.

Conclusion

This study strongly suggests the significant negative associations of OBS with HUA and gout in American adults and provides a dietary and lifestyle guideline to reduce the risks.

Diabetes mellitus as a risk factor and comorbidity in gout

INTRODUCTION

Metabolic disorders are a public health issue because of the complications they cause, but they are also a major risk factor for the onset of gout.

Prevalence and risk factors of hyperuricemia and gout: a cross-sectional survey from 31 provinces in mainland China

Background and Objetives

Hyperuricemia (HUA) and gout seriously influence patients’ quality of life. The current study was performed to investigate the prevalence of HUA and gout and the related risk factors in Chinese adults.

Methods

Data were collected from the National Survey of Thyroid Disorders and Diabetes (the Thyroid Disease, Iodine Status, and Diabetes National Epidemiological survey [TIDE]), a cross-sectional investigation conducted during 2015–2017. Using a random, multistage, and stratified sampling strategy, a representative sample (78,130 participants aged 18 years and above) was selected from the general population in 31 provinces of mainland China. The weighted prevalence rates of HUA and gout were calculated, and the related risk factors were analyzed.

Results

The weighted prevalence rates of HUA and gout in Chinese adults were 17.7% and 3.2%, respectively. The prevalence of HUA in males linearly decreased with age, while the prevalence in females showed the opposite trend (both P for trend < 0.01). The prevalence rate of gout exhibited a rising tendency with age in both genders (both P for trend < 0.05). The HUA and gout prevalence rates in males were the highest in Han and Tibetan nationalities, respectively. Logistic regression analysis showed that the morbidities of HUA and gout were differentially associated with age, residence location, nationality, smoking, and other complicating metabolic diseases in the two genders.

Conclusions

There are relatively high prevalence rates of gout and HUA in China, which is currently a developing country. Reducing their burden has become an urgent issue for Chinese people.

Pegloticase treatment of chronic refractory gout: Update on efficacy and safety

Gout is currently the most frequent cause of inflammatory arthritis worldwide. It results from elevated serum urate and subsequent deposition of monosodium urate crystals in joints and other tissues. While many patients with gout can be managed with conventional agents (e.g., allopurinol, febuxostat), those with chronic refractory gout often fail to achieve treatment goals with these agents. Pegloticase is a recombinant, pegylated mammalian uricase developed for treatment of chronic refractory gout. Pegloticase is different than other urate lowering therapies in that it enzymatically degrades urate. Pegloticase has been evaluated in multiple studies, most importantly in two randomized controlled trials and a follow-up open-label extension. Extensive analysis of results from these studies has shown that pegloticase profoundly lowers serum urate, resolves tophi, reduces tender and swollen joint counts, decreases pain, and improves both patients' global assessments and quality of life. Pegloticase also significantly decreases blood pressure in patients with chronic refractory gout, but has no significant effect on renal function. Post hoc analyses of clinical results also indicated that chronic refractory gout patients not achieving sustained urate lowering still have significant clinical benefits with pegloticase treatment. The major limitation of pegloticase is immunogenicity and the emergence of anti-drug antibodies that result in increased drug clearance, loss of efficacy, and infusion reactions. However, these reactions can be avoided by stopping pegloticase when there is a loss of serum urate lowering. New dosing regimens and co-administration of immunosuppressive agents are also being employed to overcome this limitation and extend the benefits of pegloticase to a larger number of patients.

Hyperuricemia is associated with decreased renal function and occurrence of end-stage renal disease in patients with microscopic polyangiitis and granulomatosis with polyangiitis: a retrospective study

Current evidence suggests that high uric acid levels are associated with accelerated renal damage. However, the clinical impact of serum uric acid level on patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) is unknown. We aimed to evaluate the impact of hyperuricemia on such patients. A retrospective study was performed to obtain patients' demographic, clinical, and laboratory data from when they were diagnosed with MPA and GPA. Multivariable logistic regression and Cox hazard model analyses were performed to evaluate factors associated with hyperuricemia at diagnosis and predictive factors of end-stage renal disease (ESRD) development. Among 156 patients, 35 (22.4%) had hyperuricemia at baseline. Hyperuricemic patients had renal manifestation and impaired renal function more frequently than non-hyperuricemic patients. Logistic regression analysis revealed that serum creatinine was significantly associated with hyperuricemia at diagnosis [odds ratio 1.995; 95% confidence interval (CI), 1.503-2.648; P < 0.001]. Cox hazard model analysis revealed that body mass index and serum creatinine were significantly associated with ESRD when all variables were included, but hyperuricemia was independently associated with ESRD [hazard ratio (HR), 3.799; 95% CI 1.719-8.222; P < 0.001) when serum creatinine was excluded. Additionally, in a subgroup analysis of patients with decreased glomerular filtration rates (GFRs), serum uric acid was the sole predictor of ESRD (HR, 1.243; 95% CI 1.048-1.475; P = 0.013). Hyperuricemia is associated with renal damage and ESRD occurrence in MPA and GPA patients. Serum uric acid level is associated with ESRD occurrence in patients with decreased GFRs.

Effects of Uric Acid on Diabetes Mellitus and Its Chronic Complications

With the deepening of the researches on uric acid, especially in the study of metabolic diseases, uric acid has been found to be closely related to obesity, metabolic syndrome, nonalcoholic fatty liver disease, diabetes, and other metabolic diseases. Uric acid causes a series of pathophysiological changes through inflammation, oxidative stress, vascular endothelial injury, and so on and thus subsequently promotes the occurrence and development of diseases. This review confirmed the positive correlation between uric acid and diabetes mellitus and its chronic complications through the pathogenesis and clinical studies aspects.

Pegloticase Treatment Significantly Decreases Blood Pressure in Patients With Chronic Gout

Serum urate is correlated with blood pressure (BP), and lowering urate may decrease BP, but a consistent effect has not been observed. Here, we evaluated whether pegloticase, a recombinant uricase conjugated to polyethylene glycol, which can lead to persistently low serum urate levels (<1 mg/dL), can modulate BP in subjects with chronic refractory gout. This post hoc analysis used results from two 6-month randomized clinical trials in which subjects were treated with 8 mg pegloticase every 2 or 4 weeks (q2w or q4w) or placebo. Responders in this study were defined as those individuals in whom a persistently low urate level (<6 mg/dL and usually <1 mg/dL) was maintained. Serial sitting BP was measured in 173 subjects, and estimated glomerular filtration rate was determined at baseline and after 3 and 6 months. Significant reductions in mean arterial pressure (MAP) from baseline to 6 months were noted in q2w responders ( P=0.0028), whereas reductions in MAP in other groups were not significant. Significant decreases in both systolic and diastolic BP paralleled the change in MAP. Of the 62% of q2w responders exhibiting persistent decreases in MAP, there were no significant differences in baseline age, sex, race, weight, body mass index, history of hypertension, hyperlipidemia, history of coronary artery disease, gout duration, MAP, serum urate, estimated glomerular filtration rate or urinary uric acid/creatinine ratio compared with those who did not lower MAP. No significant changes in estimated glomerular filtration rate occurred in any of the groups during the study. Responders to biweekly pegloticase who maintained a persistently lower serum urate level throughout the trial experienced significant reductions in both systolic and diastolic BP that were independent of changes in renal function. Clinical Trial Registration- URL: http://www.clinicaltrials.gov . Unique identifier: NCT00325195.

The association between gout and cardiovascular disease in patients with atrial fibrillation

Objective

Gout is a sign of a disturbed metabolism and associated with atrial fibrillation (AF) and other cardio-vascular diseases. Our aim was to study associations between gout and cardiovascular co-morbidities in patients with AF.

Methods

The study population included all adults (n=12,283) ≥45 years diagnosed with AF visiting 75 primary care centers in Sweden 2001-2007. Logistic regression was used to calculate odds ratios with 95% confidence intervals (CIs) for the associations between prevalent gout and cardiovascular co-morbidities. In subsamples we studied incident congestive heart failure (CHF) and ischemic stroke (IS), excluding patients with earlier registered specific diagnosis, using Cox regression (to estimate hazard ratios (HR) with 95% CIs).

Results

Gout was significantly and positively associated with CHF, obesity and diabetes among men and women, and among men also with hypertension and coronary heart disease. Prevalent gout was negatively associated with incident IS (HR and 95% CI: 0.64, 0.49-0.82; 0.50, 0.39-0.64) in both full model (adjusted for sex, age, socio-economic factors and comorbidities) and CHA₂DS₂-VASc model (adjusted for CHA₂DS₂-VASc, sex and age). Adding gout to full model increased Harrell's C by 1% in CHA₂DS₂-VASc model.

Conclusions

In this clinical setting we found gout to be associated with most cardiometabolic diseases except cerebrovascular diseases, and with decreased risk of IS, with gout adding significantly to the predictive value compared to CHA₂DS₂-VASc without gout included.

Impact of long-term potassium supplementation on thiazide diuretic-induced abnormalities of glucose and uric acid metabolisms

Treatment of hypertension with thiazide diuretics may trigger hypokalemia, hyperglycemia, and hyperuricemia. Some studies suggest simultaneous potassium supplementation in hypertensive patients using thiazide diuretics. However, few clinical studies have reported the impact of long-term potassium supplementation on thiazide diuretic-induced abnormalities in blood glucose and uric acid (UA) metabolisms. One hundred hypertensive patients meeting the inclusion criteria were equally randomized to two groups: IND group receiving indapamide (1.25-2.5 mg daily) alone, and IND/KCI group receiving IND (1.25-2.5 mg daily) plus potassium chloride (40 mmol daily), both for 24 weeks. At the end of 24-week follow-up, serum K⁺ level in IND group decreased from 4.27 ± 0.28 to 3.98 ± 0.46 mmol/L (P < 0.001), and fasting plasma glucose (FPG) and UA increased from 5.11 ± 0.52 to 5.31 ± 0.57 mmol/L (P < 0.05), and from 0.404 ± 0.078 to 0.433 ± 0.072 mmol/L (P < 0.05), respectively. Serum K⁺ level in IND/KCl group decreased from 4.27 ± 0.36 to 3.89 ± 0.28 mmol/L (P < 0.001), and FPB and UA increased from 5.10 ± 0.41 to 5.35 ± 0.55 mmol/L (P < 0.01), and from 0.391 ± 0.073 to 0.457 ± 0.128 mmol/L (P < 0.001), respectively. The difference value between the serum K⁺ level and FPG before and after treatment was not statistically significant between the two groups. However, the difference value in UA in IND/KCl group was significantly higher than that in IND group (0.066 (95% confidence interval (CI): 0.041-0.090)  mmol/L vs. 0.029 (95% CI: 0.006-0.058) mmol/L, P < 0.05). The results showed that long-term routine potassium supplementation could not prevent or attenuate thiazide diuretic-induced abnormalities of glucose metabolism in hypertensive patients; rather, it may aggravate the UA metabolic abnormality.

Identification of Metabolite Biomarkers for Gout Using Capillary Ion Chromatography with Mass Spectrometry

Gout is a common form of inflammatory arthritis, and the detailed pathogenic mechanisms for this metabolic disorder remain largely unknown. In this study, we first profiled the salivary metabolites in 8 patients with gout, 15 patients with hyperuricaemia (HUA), and 15 healthy individuals using capillary ion chromatography (CIC) with tandem mass spectrometry (MS/MS). Forty-nine salivary metabolites were found to be significantly changed between gout patient and healthy control groups, and 26 salivary metabolites were significantly different between gout and HUA patient groups. Three metabolite biomarkers, uric acid, oxalic acid, and l-homocysteic acid (HCA), were selected for validation in the saliva samples of 30 patients with gout, 30 patients with HUA, and 30 healthy control subjects. By using commercial assay kits for the measurements, salivary uric acid and oxalic acid levels were found to be significantly higher in gout patients than healthy controls, whereas salivary HCA level was significantly higher in gout patients than both HUA patients and healthy controls. These assay measurements were in line with those obtained by CIC-MS/MS. In conclusion, we have demonstrated a new application of CIC-MS/MS for the discovery of novel metabolite biomarkers of gout. Validated biomarkers may be used for noninvasive, diagnostic and prognostic applications in gout. Future studies are warranted to investigate the clinical utility of these identified biomarkers for monitoring gout flare and/or treatment efficacy.

Gout in immigrant groups: a cohort study in Sweden

Our aim was to study the association between country of birth and incidence of gout in different immigrant groups in Sweden. The study population included the whole population of Sweden. Gout was defined as having at least one registered diagnosis in the National Patient Register. The association between incidence of gout and country of birth was assessed by Cox regression, with hazard ratios (HRs) and 95% confidence intervals (95% CI), using Swedish-born individuals as referents. All models were conducted in both men and women, and the full model was adjusted for age, place of residence in Sweden, educational level, marital status, neighbourhood socio-economic status and co-morbidities. The risk of gout varied by country of origin, with highest estimates, compared to Swedish born, in fully adjusted models among men from Iraq (HR 1.82, 95% CI 1.54-2.16), and Russia (HR 1.69, 95% CI 1.26-2.27), and also high among men from Austria, Poland, Africa and Asian countries outside the Middle East; and among women from Africa (HR 2.23, 95% CI 1.50-3.31), Hungary (HR 1.98, 95% CI 1.45-2.71), Iraq (HR 1.76, 95% CI 1.13-2.74) and Austria (HR 1.70, 95% CI 1.07-2.70), and also high among women from Poland. The risk of gout was lower among men from Greece, Spain, Nordic countries (except Finland) and Latin America and among women from Southern Europe, compared to their Swedish counterparts. The increased risk of gout among several immigrant groups is likely explained by a high cardio-metabolic risk factor pattern needing attention.

Evaluation of cardiovascular risk in stages of gout by a complex multimodal ultrasonography

The aim of our work was to assess ultrasound features of cardiovascular (CV) risk in stages of gout. Cross-sectional complex multimodal ultrasound study of 169 age-matched patients, with similar distribution of arterial hypertension, diabetes mellitus, obesity and chronic renal failure, was divided into four groups: 41 with asymptomatic hyperuricemia, 52 gout without tophi, 42 gouty tophi and 34 controls with osteoarthritis. Parameters independently associated with CV risk were measured: renal resistive index (RRI), left ventricular mass index (LVMi), mitral annulus early diastolic velocity (e'), intima-media thickness (IMT) and common carotid artery resistive index (CCARI). Multivariate analyses were performed to evaluate the impact of gout stages and CV risk factors on ultrasound alterations. Gouty tophi increased the risk of having IMT >0.90 mm with an OR 11.51 (95 % CI 2.32-57.21, p = 0.003), gout without tophi raised the risk with an OR 6.25 (95 % CI 1.37-28.44, p = 0.018), while asymptomatic hyperuricemia had no effect on IMT. The category of CCARI >0.70 was influenced by tophi with an OR 11.18 (95 % CI 2.61-47.83, p = 0.001) and by arterial hypertension with an OR 3.22 (95 % CI 1.11-9.36, p = 0.032). Neither asymptomatic hyperuricemia nor gout without tophi modified the development of abnormally high CCARI. Gout stages had no impact on LVMi, e' and RRI. Tophi are related to worsened ultrasonographic parameters evaluating target organs in gout, relative to earlier stages of the disease. They create a strong risk of carotid arteries' changes even beyond arterial hypertension.

Gout and its comorbidities in the total population of Stockholm

OBJECTIVE

Study of prevalence of gout with concomitant diseases.

METHODS

Study population included all living persons in Stockholm County, Sweden, on January 1st 2013 (N=2,124,959). A diagnosis of gout was identified during 2013-2014, with information of diabetes mellitus and insulin resistance, hypertension, chronic heart failure, chronic kidney disease, alcohol abuse, and malignancies. Age-adjusted odds ratios (ORs) with 95% confidence intervals (95% CI) for women and men with gout, using individuals without gout as referents, were calculated.

RESULTS

Age-adjusted odds of co-morbidities among individuals with gout vs. those without gout were: diabetes mellitus and insulin resistance 3.97 (95% CI 3.65-4.31) in women and 1.88 (95% CI 1.78-1.99) in men; hypertension 4.02 (95% CI 3.69-4.37) in women and 3.21 (95% CI 3.06-3.37) in men; chronic heart failure 4.72 (95% CI 4.31-5.19) in women and 2.84 (95% CI 2.66-3.04) in men; chronic kidney disease 2.08 (95% CI 1.50-2.87) in women and 2.39 (95% CI 2.15-2.66) in men; alcohol abuse 8.98 (95% CI 8.15-9.80) in women and 4.38 (95% CI 4.10-4.69) in men; and malignancies 1.32 (95% CI 1.17-1.48) in women and 1.13 (95% CI 1.06-1.21) men.

CONCLUSION

Gout is a warning sign for concomitant diseases, e.g. alcoholism, diabetes, cardiovascular diseases, and cancer. KEY MESSAGES.

Bidirectional Association between Self-Reported Hypertension and Gout: The Singapore Chinese Health Study

It has been hypothesized that the association between hypertension and gout is bidirectional, however, few studies have examined this in a prospective cohort. We analyzed data from the Singapore Chinese Health Study (SCHS) follow-up I (1999–2004) and II (2006–2010) interviews, when both physician-diagnosed hypertension and gout were self-reported. We included participants with data for both follow-up interviews and who were free of heart disease, stroke and cancer at follow-up I. The analysis of hypertension and risk of gout included 31,137 participants when prevalent gout cases were excluded, while the analysis of gout and risk of hypertension included 20,369 participants when prevalent hypertension cases were excluded. Cox proportional hazards models were used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). The mean age at follow-up I was 60.1 (SD 7.3) years, and the average follow-up was 6.8 (SD 1.4) years. In the analysis of hypertension and risk of gout, 682 incident cases were identified. Compared to normotensive participants, hypertensive patients had an88% increased risk of developing gout (HR 1.88; 95% CI 1.61–2.21). In the parallel analysis, 5,450 participants reported to have newly diagnosed hypertension during follow-up. Compared to participants without gout, those with gout had an18% increased risk of developing hypertension (HR 1.18; 95% CI 1.02–1.37). The bidirectional association was stronger in normal weight adults compared to overweight/obese individuals (P_interaction = 0.06 and 0.04, respectively). The hypertension to gout association was stronger in women compared to men (P_interaction = 0.04), while the gout to hypertension association was evident in women but not in men (P_interaction = 0.02). In conclusion, our results suggest that the hypertension-gout association is bidirectional in this cohort of Singapore Chinese adults. The potential interactions of the bidirectional association with obesity and sex deserve further investigations.

Effects of combined enalapril and folic acid therapy on the serum uric acid levels in hypertensive patients: a multicenter, randomized, double-blind, parallel-controlled clinical trial

Objective The efficacy of combined treatment consisting of enalapril and folic acid (FA) was compared to that of enalapril alone in reducing the serum uric acid (UA) levels in adult hypertensive patients in China. Methods Patients with mild to moderate hypertension (n=480) were randomly assigned to one of three treatment groups: (1) 10 mg enalapril (control group), (2) 10 mg enalapril plus 0.4 mg FA (low-FA group) or (3) 10 mg enalapril plus 0.8 mg FA (high-FA group) daily for eight weeks. The primary outcome was the UA ratio (week 8 UA: baseline UA). Results The final analysis included 450 patients (43.1% men, 27-75 years of age). An adjusted multivariable regression analysis revealed no significant differences in the UA ratio between the three groups after eight weeks of treatment. In the subgroup analysis stratified according to the baseline UA level, the high-FA group demonstrated a significantly greater UA-lowering response among the patients with an elevated baseline UA concentration (UA ≥310 μmol/L) [median UA ratio (25th percentile, 75th percentile): 0.94 (0.83, 1.01)], compared with that observed in the control group [0.97 (0.90, 1.00), p=0.025]. Similar results were found in the participants with baseline hyperuricemia (HUA; UA: men >420 μmol/L, women >350 μmol/L). Conclusion In this sample of adult hypertensive patients, the administration of a daily dose of 10 mg of enalapril combined with 0.8 mg of FA had a greater beneficial effect on the serum UA levels than did that of 10 mg of enalapril alone in patients with either an elevated UA concentration or HUA.

Improving cardiovascular and renal outcomes in gout: what should we target?

Epidemiological and experimental studies have shown that hyperuricaemia and gout are intricately linked with hypertension, metabolic syndrome, chronic kidney disease and cardiovascular disease. A number of studies suggest that hyperuricaemia and gout are independent risk factors for the development of these conditions and that these conditions account, in part, for the increased mortality rate of patients with gout. In this Review, we first discuss the links between hyperuricaemia, gout and these comorbidities, and present the mechanisms by which uric acid production and gout might favour the development of cardiovascular and renal diseases. We then emphasize the potential benefit of urate-lowering therapies on cardiovascular and renal outcomes in patients with hyperuricaemia. The mechanisms that link elevated serum uric acid levels and gout with these comorbidities seem to be multifactorial, implicating low-grade systemic inflammation and xanthine oxidase (XO) activity, as well as the deleterious effects of hyperuricaemia itself. Patients with asymptomatic hyperuricaemia should be treated by nonpharmacological means to lower their SUA levels. In patients with gout, long-term pharmacological inhibition of XO is a treatment strategy that might also reduce cardiovascular and renal comorbidities, because of its dual effect of lowering SUA levels as well as reducing free-radical production during uric acid formation.

Potential role of uric acid in metabolic syndrome, hypertension, kidney injury, and cardiovascular diseases: is it time for reappraisal?

Elevated serum uric acid concentration is a common laboratory finding in subjects with metabolic syndrome/obesity, hypertension, kidney disease and cardiovascular events. Hyperuricemia has been attributed to hyperinsulinemia in metabolic syndrome and to decreased uric acid excretion in kidney dysfunction, and is not acknowledged as a main mediator of metabolic syndrome, renal disease, and cardiovascular disorder development. However, more recent investigations have altered this traditional view and shown, by providing compelling evidence, to support an independent link between hyperuricemia and increased risk of metabolic syndrome, diabetes, hypertension, kidney disease and cardiovascular disorders. However, despite these new findings, controversy regarding the exact role of uric acid in inducing these diseases remains to be unfolded. Furthermore, recent data suggest that the high-fructose diet in the United State, as a major cause of hyperuricemia, may be contributing to the metabolic syndrome/obesity epidemic, diabetes, hypertension, kidney disease and cardiovascular disorder. Our focus in this review is to discuss the available evidence supporting a role for uric acid in the development of metabolic syndrome, hypertension, renal disease, and cardiovascular disorder; and the potential pathophysiology mechanisms involved.

Protective effect of iridoid glycosides from Paederia scandens (LOUR.) MERRILL (Rubiaceae) on uric acid nephropathy rats induced by yeast and potassium oxonate

Iridoid glycosides of Paederia scandens (IGPS) are an active component isolated from Chinese herb P. scandens (LOUR.) MERRILL (Rubiaceae). Uric acid nephropathy (UAN) is caused by excessive uric acid, which results in damage of kidney tissue via urate crystals deposition in the kidneys. This study aimed to investigate the protective effects of IGPS on UAN in rats induced by yeast and potassium oxonate. Treatment groups received different doses of IGPS and allopurinol (AP) daily for 35 days respectively. The results showed that treatment with IGPS significantly prevented the increases of uric acid in serum and the elevation of systolic blood pressure (SBP), attenuated renal tissue injury, improved renal function and reserved the biological activity of NOS-1. IGPS also inhibited the biological activity of TNF-α and TGF-β1, and suppressed the mRNA expressions of TNF-α and TGF-β1 in renal tissue. Taken together, the present and our previous findings suggest that IGPS exerts protective effects against kidney damage in UAN rats through its uric acid-lowering, anti-inflammatory and immunomodulatory properties. Furthermore, decreasing SBP by up regulation of NOS-1 expression and down regulation of TNF-α and TGF-β1 expression are involved in the effect of IGPS on high uric acid-induced nephropathy.