Benzbromarone Attenuates Oxidative Stress in Angiotensin II- and Salt-Induced Hypertensive Model Rats

Management of hypertension addressing hyperuricaemia: introduction of nano-based approaches

Uric acid (UA) levels in blood serum have been associated with hypertension, indicating a potential causal relationship between high serum UA levels and the progression of hypertension. Therefore, the reduction of serum UA level is considered a potential strategy for lowering and mitigating blood pressure. If an individual is at risk of developing or already manifesting elevated blood pressure, this intervention could be an integral part of a comprehensive treatment plan. By addressing hyperuricaemia, practitioners may subsidize the optimization of blood pressure regulation, which illustrates the importance of addressing UA levels as a valuable strategy within the broader context of hypertension management. In this analysis, we outlined the operational principles of effective xanthine oxidase inhibitors for the treatment of hyperuricaemia and hypertension, along with an exploration of the contribution of nanotechnology to this field.

Urate-lowering agents do not have clinically relevant negative effects on sperm quality and reproductive hormones in men with gout: a prospective open-label cohort study

OBJECTIVE

The objective of this study was to analyze and compare the effects of different urate-lowering agents on testicular functions in men with gout in a clinical setting.

METHODS

In this prospective cohort study (Clinical Trial Registration Number: NCT04213534), a total of 49 male patients aged 18-45 years with gout were enrolled. They were divided into three groups and received treatment with either allopurinol, febuxostat or benzbromarone for a duration of 3 months. Semen parameters, reproductive hormones and biochemical assessments were evaluated at baseline, month 1, and month 3.

RESULTS

Overall, 40 individuals (81.6%) completed the follow-up visits. In allopurinol group, there were no significant differences in semen parameters from baseline to month 3. Most of sperm parameters in febuxostat group did not show notable changes, except for a decrease in sperm motility at month 3(33.6%, [22.9-54.3] vs 48.4%, [27.4-67.6], p = 0.033). However, the total motile sperm count did not differ significantly after febuxostat treatment. Surprisingly, administration of benzbromarone resulted in improved sperm concentration (37.19 M/mL, [29.6-69.92] vs 58.5 M/mL, [49.8-116.6], p = 0.001). There were no significant changes observed in sperm DNA integrity and reproductive hormones in the three groups from baseline to month 3. The incidence of adverse events did not differ significantly among the three groups as well.

CONCLUSION

This study is the first to demonstrate that urate-lowering agents, allopurinol and febuxostat, do not have clinically relevant negative effects on sperm quality and reproductive hormones in men with gout, and benzbromarone presents improving sperm concentration. Results provide important preliminary guidance for the development of reproductive health management guidelines for patients RCID with gout.

Drug repurposing and structure-based discovery of new PDE4 and PDE5 inhibitors

Phosphodiesterase-4 (PDE4) and PDE5 responsible for the hydrolysis of intracellular cAMP and cGMP, respectively, are promising targets for therapeutic intervention in a wide variety of diseases. Here, we report the discovery of novel, drug-like PDE4 inhibitors by performing a high-throughput drug repurposing screening of 2560 approved drugs and drug candidates in clinical trial studies. It allowed us to identify eight potent PDE4 inhibitors with IC50 values ranging from 0.41 to 2.46 μM. Crystal structures of PDE4 in complex with four compounds, namely ethaverine hydrochloride (EH), benzbromarone (BBR), CX-4945, and CVT-313, were further solved to elucidate molecular mechanisms of action of these new inhibitors, providing a solid foundation for optimizing the inhibitors to improve their potency as well as selectivity. Unexpectedly, selectivity profiling of other PDE subfamilies followed by crystal structure determination revealed that CVT-313 was also a potent PDE5 inhibitor with a binding mode similar to that of tadalafil, a marketed PDE5 inhibitor, but distinctively different from the binding mode of CVT-313 with PDE4. Structure-guided modification of CVT-313 led to the discovery of a new inhibitor, compound 2, with significantly improved inhibitory activity as well as selectivity towards PDE5 over PDE4. Together, these results highlight the utility of the drug repurposing in combination with structure-based drug design in identifying novel inhibitors of PDE4 and PDE5, which provides a prime example for efficient discovery of drug-like hits towards a given target protein.

Uric acid-lowering therapy with benzbromarone in hypertension with asymptomatic hyperuricemia: a randomized study focusing left ventricular diastolic function

BACKGROUND

Both hypertension and hyperuricemia are closely associated with the morbidity and mortality of heart failure with preserved ejection fraction (HFpEF). However, there is limited evidence on the effect of uric acid-lowering therapy on left ventricular (LV) diastolic function in this population. In this randomized study, we prescribed benzbromarone, a uric acid-lowering drug, to those with hypertension and asymptomatic hyperuricemia to investigate its clinical benefits by evaluating LV diastolic function, incidence of HFpEF and hospitalization for heart failure and cardiovascular death.

METHODS

230 participants were randomly assigned into two groups: uric acid-lowering group (benzbromarone) and control groups (without uric acid-lowering drug). The primary endpoint was LV diastolic function evaluated by echocardiography. The secondary endpoint of composite endpoints is the combination of new-onset HFpEF, hospitalization for heart failure and cardiovascular death.

RESULTS

After a median of 23.5 months' follow-up (16-30 months), the primary endpoint reflected by E/e' in benzbromarone group reached a significant improvement when compared to control group (p <.001). Composite endpoints occurred in 11 patients of the control group while only 3 patients occurred in the benzbromarone group (p = .027). We also presented the favorable trend of freedom from the composite endpoints or new-onset HFpEF using Kaplan-Meier curve by log-rank test in benzbromarone group (p = .037 and p = .054).

CONCLUSIONS

Our study demonstrated the efficiency of benzbromarone in hypertensive patients with concomitant asymptomatic hyperuricemia, including the benefits on ameliorating LV diastolic dysfunction as well as improving composite endpoints.

Cardiovascular risk associated with allopurinol or benzbromarone treatment in patients with gout

Background:

In previous studies, cardiovascular (CV) risk was increased in patients with gout. The effects of uric acid–lowering therapy on CV risk in gout patients have been investigated in numerous studies; however, allopurinol and benzbromarone have rarely been compared.

Objectives:

To compare CV risk based on allopurinol and benzbromarone treatment in Korean gout patients.

Design:

A nationwide population-based retrospective cohort study.

Methods:

We used South Korea database of the Health Insurance Review and Assessment (HIRA) service to identify gout patients ⩾18 years of age who newly started allopurinol or benzbromarone between 2009 and 2015. The primary outcome of the study was the occurrence of a composite CV endpoint, which included coronary revascularization, hospitalization due to myocardial infarction, ischemic stroke, and transient ischemic attack. Cox proportional hazard regression analysis and Kaplan–Meier curves were used for analysis.

Results:

The study included 257,097 allopurinol initiators and 7868 benzbromarone initiators. Compared with allopurinol initiators, the adjusted hazard ratio (aHR) of the composite CV endpoint of benzbromarone initiators was 1.01 [95% confidence interval (CI): 0.83−1.21], which was not significantly different. The results did not change even when 1:3 propensity score matching was performed for baseline characteristics. In subgroup analysis of high-risk patients with CV disease, significant difference was not observed between allopurinol and benzbromarone initiators.

Conclusion:

In this study, significant difference was not found in CV risk between allopurinol and benzbromarone initiators. In the high-CV-risk group, the incidence of CV events did not differ between allopurinol and benzbromarone initiators.

Research progress on related mechanisms of uric acid activating NLRP3 inflammasome in chronic kidney disease

Hyperuricemia is an independent risk factor for the progression of chronic kidney disease. High levels of uric acid can lead to a series of pathological conditions, such as gout, urinary stones, inflammation, and uric acid nephropathy. There is a close relationship between uric acid and the NLRP3 inflammasome. NLRP3 inflammasome activation can cause cell damage and even death through endoplasmic reticulum stress, lysosome destruction, mitochondrial dysfunction, and the interaction between the Golgi apparatus and extracellular vesicles. In addition, the NLRP3 inflammasome acts as a molecular platform, triggering the activation of caspase-1 and the lysis of IL-1β, IL-18 and Gasdermin D (GSDMD) through different molecular mechanisms. Cleaved NT-GSDMD forms pores in the cell membrane and triggers pyrophosphorylation, thereby inducing cell death and releasing many intracellular proinflammatory molecules. In recent years, studies have found that hyperuricemia or uric acid crystals can activate NLRP3 inflammasomes, and the activation of NLRP3 inflammasomes plays an important role in kidney disease. This article reviews the possible pathophysiological mechanisms by which uric acid activates inflammasomes and induces kidney damage at the cellular and molecular levels.

Hyperuricaemia is an important risk factor of the erectile dysfunction: A systematic review and meta-analysis

Serum uric acid can affect endothelial function, and hyperuricaemia-induced endothelial dysfunction is involved in the pathogenesis of cardiovascular diseases. As endothelial dysfunction is also a main pathogenic mechanism of erectile dysfunction (ED), the present study aims to evaluate the relationship between hyperuricaemia and ED via systemic review and meta-analysis. Five cohort studies and six cross-sectional studies on hyperuricaemia and ED, including a total of 454,510 participants, were recruited. Odds ratio (OR) and the 95% confidence intervals (CI) were adopted to estimate the relationship between hyperuricaemia and ED. Overall risk on effects of urate-lowering therapy (ULT) were analysed. In addition, subgroup analyses on study design, populations, age stratification and the object were conducted. In the patients with hyperuricaemia, the risk of ED was 1.59-fold higher than (pooled OR = 1.59, 95% CI [1.29, 1.97]) the non-hyperuricaemia counterparts. Urate-lowing therapy (ULT) in these hyperuricaemia patients reduced the risk of ED by 27% (OR = 1.27, 95% CI [1.14, 1.41]). After subgroup analysis, the association between hyperuricaemia and ED remained significant apart from the >60 years subgroup. Hyperuricaemia is an important risk factor of ED, while ULT can reduce the risk of ED in hyperuricaemia. This study suggests that hyperuricaemia-associated endothelial dysfunction may also underlie the pathogenesis of ED in these patients.

Cardiovascular risk associated with allopurinol vs. benzbromarone in patients with gout

Aims 

With the high prevalence of gout and associated cardiovascular (CV) diseases, information on the comparative CV safety of individual urate-lowering drugs becomes increasingly important. However, few studies examined the CV risk of uricosuric agents. We compared CV risk among patients with gout who initiated allopurinol vs. benzbromarone.

Methods and results 

Using the Korean National Health Insurance claims data (2002–17), we conducted a cohort study of 124 434 gout patients who initiated either allopurinol (n = 103 695) or benzbromarone (n = 20 739), matched on propensity score at a 5:1 ratio. The primary outcome was a composite CV endpoint of myocardial infarction, stroke/transient ischaemic attack, or coronary revascularization. To account for competing risk of death, we used cause-specific hazard models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the outcomes comparing allopurinol initiators with benzbromarone. Over a mean follow-up of 1.16 years, 2258 patients developed a composite CV event. The incidence rate of the composite CV event was higher in allopurinol initiators (1.81 per 100 person-years) than benzbromarone (1.61 per 100 person-years) with a HR of 1.22 (95% CI 1.05–1.41). The HR for all-cause mortality was 1.66 (95% CI 1.43–1.93) among allopurinol initiators compared with benzbromarone.

Conclusion 

In this large population-based cohort of gout patients, allopurinol was associated with an increased risk of composite CV events and all-cause mortality compared to benzbromarone. Benzbromarone may reduce CV risk and mortality in patients with gout, although more studies are necessary to confirm our findings and to advance our understanding of the underlying mechanisms.

The Protective Effects of Benzbromarone Against Propofol-Induced Inflammation and Injury in Human Brain Microvascular Endothelial Cells (HBMVECs)

It has been widely reported that severe neurotoxicity can be induced by the application of propofol, which is closely related to the disruption of the blood-brain barrier (BBB) induced by inflammation and injury in the human brain microvascular endothelial cells (HBMVECs). Benzbromarone is a classic anti-gout agent that has been recently reported to exert anti-inflammatory and anti-oxidative stress effects. In the present study, we aim to investigate the protective property of Benzbromarone against propofol-induced injury on HBMVECs and the underlying mechanism. CCK8 assay was used to detect the cell viability of treated HBMVECs. Oxidative stress in HBMVECs was evaluated by measuring the levels of MDA and mitochondrial ROS. ELISA and qRT-PCR assay were used to determine the production of IL-1β, IL-8, MCP-1, ICAM-1, and VCAM-1 by treated HBMVECs. Calcein-AM staining was utilized to evaluate the attachment of U937 monocytes to HBMVECs. The expression level of Egr-1 was determined by qRT-PCR and Western blot assay. Firstly, the decreased cell viability of HBMVECs induced by propofol was significantly elevated by treatment with Benzbromarone. The increased levels of MDA and mitochondrial ROS induced by propofol were dramatically suppressed by Benzbromarone. Secondly, the excessive production of inflammatory factors (IL-1β, IL-8, and MCP-1) and adhesion molecules (ICAM-1 and VCAM-1) triggered by propofol was pronouncedly inhibited by Benzbromarone. Benzbromarone ameliorated propofol-induced attachment of U937 monocytes to HBMVECs. Lastly, Benzbromarone downregulated propofol-induced expression of the transcriptional factor Egr-1 in HBMVECs. Benzbromarone protected against propofol-induced inflammation and injury through suppressing Egr-1 in human brain vascular endothelial cells.

Interaction of Benzbromarone with Subdomains IIIA and IB/IIA on Human Serum Albumin as the Primary and Secondary Binding Regions

Benzbromarone has been used for the treatment of gout for more than 30 years. Although it shows a high level of binding to plasma proteins (>99%), our knowledge of this binding is not sufficiently extensive to permit us to understand its pharmacokinetics and pharmacodynamics. To address this issue in more detail, we characterized the binding of benzbromarone to human serum albumin (HSA), the most abundant protein in plasma. Equilibrium dialysis and circular dichroism findings indicated that benzbromarone binds strongly to one primary as well as to multiple secondary sites on HSA and that the bromine atoms of benzbromarone play important roles in this high affinity binding. An X-ray crystallographic study revealed that benzbromarone molecules bind to hydrophobic pockets within subdomains IB, IIA, and IIIA. Inhibition experiments using site specific ligands (subdomain IB; fusidic acid, IIA; warfarin, IIIA; diazepam) indicated that the primary and secondary binding sites that benzbromarone binds to are within subdomains IIIA and IB/IIA, respectively. Lastly, a study of the effect of fatty acids on the benzbromarone-HSA interaction suggested that benzbromarone, when displaced from subdomain IIIA by sodium oleate, could transfer to subdomains IB or IIA. Thus, these data will permit more relevant assessments of the displacement interactions of benzbromarone especially in cases of co-administered drugs or endogenous compounds that also bind to subdomain IIIA. In addition, the findings presented herein will also be useful for designing drug combination therapy in which pharmacokinetic and pharmacodynamic performance need to be controlled.

Association Between Use of Anti-gout Preparations and Dementia: Nested Case-Control Nationwide Population-Based Cohort Study

Objectives: Gout is the most common form of inflammatory arthritis and was found to be independently associated with incident dementia in the elderly. However, the associations between anti-gout preparations and dementia were not well-studied.

Methods: Data were collected from Taiwan's National Health Insurance Research Database (NHIRD). A 2005–2013 retrospective cohort study was conducted, and all investigated subjects were identified by International Statistical Classification of Diseases and Related Health Problems, 9th Revision, Clinical Modification. Conditional logistic regression was used to evaluate the odds ratio of dementia in relation to different gout preparations (benzbromarone, allopurinol, sulfinpyrazone, probenecid) and number of days of anti-gout preparation use, after adjustment for potential confounding variables.

Results: A total of 3,242 gout patients with and without dementia were selected from the NHIRD and included in the final analysis after 1:1 matching for age, gender, and diagnosis year of gout. In the anti-gout preparations, only use of Benzbromarone decreased the risk of dementia (adjusted OR, 0.81; 95% CI, 0.68–0.97). The result of the subgroup analysis revealed a trend toward a lower risk of dementia with longer use of benzbromarone. Use of benzbromarone for ≥180 days showed a significantly lower risk of dementia (adjusted OR, 0.72; 95% CI, 0.58–0.89). Moreover, the protective effect was more pronounced in males compared with females.

Conclusion: This cohort study reveals that gout patients taking benzbromarone are at a decreased risk of developing incident dementia, especially with longer use and in male. Further prospective trials are warranted to confirm our findings.

Sodium Thiosulfate Ameliorates Renovascular Hypertension-Induced Renal Dysfunction and Injury in Rats

BACKGROUND/AIMS

Arterial stenosis activates the renin-angiotensin-aldosterone system subsequently resulting in renovascular hypertension (RVHT) and renal oxidative injury. We explored the effect of sodium thiosulfate (STS, Na2S2O3), a developed antioxidant in clinical trial, on RVHT-induced hypertension and renal oxidative injury in rats.

METHODS

We induced RVHT in male Wistar rats with bilaterally partial ligation of renal arteries in the 2-kidney 2-clip model. We evaluated the STS effect on RVHT-induced oxidative injury and apoptosis by a chemiluminescence amplification method, Western blot, and immunohistochemistry.

RESULTS

We found STS displayed a dose-dependent antioxidant H2O2 activity and adapted the maximal scavenging H2O2 activity of STS at the dosage of 0.1 g/kg intraperitoneally 3 times/week for 4 weeks in RVHT rats. RVHT induced a significant elevation of arterial blood pressure, blood reactive oxygen species amount, neutrophil infiltration, 4-HNE and NADPH oxidase gp91 expression, Bax/Bcl-2/poly(ADP-ribose) polymerase (PARP)-mediated apoptosis formation, blue Masson-stained fibrosis, and urinary protein level. STS treatment significantly reduced hypertension, oxidative stress, neutrophil infiltration, fibrosis, and Bax/Bcl-2/PARP-mediated apoptosis formation and depressed the urinary protein level in the RVHT models.

CONCLUSION

Our results suggest that STS treatment could ameliorate RVHT hypertension and renal oxidative injury through antioxidant, antifibrotic, and antiapoptotic mechanisms.

FNDC5 Attenuates Oxidative Stress and NLRP3 Inflammasome Activation in Vascular Smooth Muscle Cells via Activating the AMPK-SIRT1 Signal Pathway

Vascular oxidative stress and inflammation play a major role in vascular diseases. This study was aimed at determining the protective roles of fibronectin type III domain-containing 5 (FNDC5) in angiotensin II- (Ang II-) induced vascular oxidative stress and inflammation and underlying mechanisms. Wild-type (WT) and FNDC5^−/− mice, primary mouse vascular smooth muscle cells (VSMCs), and the rat aortic smooth muscle cell line (A7R5) were used in the present study. Subcutaneous infusion of Ang II caused more serious hypertension, vascular remodeling, oxidative stress, NLRP3 inflammasome activation, AMPK phosphorylation inhibition, and SIRT1 downregulation in the aorta of FNDC5^−/− mice than those of WT mice. Exogenous FNDC5 attenuated Ang II-induced superoxide generation, NADPH oxidase 2 (NOX2) and NLRP3 upregulation, mature caspase-1, and interleukin-1β (IL-1β) production in A7R5 cells. The protective roles of FNDC5 were prevented by SIRT-1 inhibitor EX527, AMPK inhibitor compound C, or integrin receptor inhibitor GLPG0187. FNDC5 attenuated the Ang II-induced inhibition in SIRT1 activity, SIRT1 protein expression, and AMPKα phosphorylation in A7R5 cells, which were prevented by compound C, EX527, and GLPG0187. FNDC5 deficiency deteriorated Ang II-induced oxidative stress, NLRP3 inflammasome activation, AMPK phosphorylation inhibition, and SIRT1 downregulation in primary aortic VSMCs of mice, which were prevented by exogenous FNDC5. These results indicate that FNDC5 deficiency aggravates while exogenous FNDC5 alleviates the Ang II-induced vascular oxidative stress and NLRP3 inflammasome activation via the AMPK-SIRT1 signal pathway in VSMCs.

Targeting the ensemble of heterogeneous tau oligomers in cells: A novel small molecule screening platform for tauopathies

OBJECTIVE

Understanding the heterogeneous pathology in Alzheimer's disease and related tauopathies is one of the most urgent and fundamental challenges facing the discovery of novel disease-modifying therapies. Through monitoring ensembles of toxic and nontoxic tau oligomers spontaneously formed in cells, our biosensor technology can identify tool compounds that modulate tau oligomer structure and toxicity, providing much needed insight into the nature and properties of toxic tau oligomers.

BACKGROUND

Tauopathies are a group of neurodegenerative disorders characterized by pathologic aggregation of the microtubule binding protein tau. Recent studies suggest that tau oligomers are the primary toxic species in tauopathies.

NEW/UPDATED HYPOTHESIS

We hypothesize that tau biosensors capable of monitoring tau oligomer conformation are able to identify tool compounds that modulate the structure and conformation of these tau assemblies, providing key insight into the unique structural fingerprints of toxic tau oligomers. These fingerprints will provide gravely needed biomarker profiles to improve staging of early tauopathy pathology and generate lead compounds for potential new therapeutics. Our time-resolved fluorescence resonance energy transfer biosensors provide us an exquisitely sensitive technique to monitor minute structural changes in monomer and oligomer conformation. In this proof-of-concept study, we identified a novel tool compound, MK-886, which directly binds tau, perturbs the conformation of toxic tau oligomers, and rescues tau-induced cytotoxicity. Furthermore, we show that MK-886 alters the conformation of tau monomer at the proline-rich and microtubule binding regions, stabilizing an on-pathway oligomer.

MAJOR CHALLENGES FOR THE HYPOTHESIS

Our approach monitors changes in the ensemble of assemblies that are spontaneously formed in cells but does not specifically isolate or enrich unique toxic tau species. However, time-resolved fluorescence resonance energy transfer does not provide high-resolution, atomic scale information, requiring additional experimental techniques to resolve the structural features stabilized by different tool compounds.

LINKAGE TO OTHER MAJOR THEORIES

Our biosensor technology is broadly applicable to other areas of tauopathy therapeutic development. These biosensors can be readily modified for different isoforms of tau, specific post-translational modifications, and familial Alzheimer's disease-associated mutations. We are eager to explore tau interactions with chaperone proteins, monitor cross-reactivity with other intrinsically disordered proteins, and target seeded oligomer pathology.

Relationship between carotid-femoral pulse wave velocity and uric acid in subjects with hypertension and hyperuricemia

Increasing of arterial stiffness is the pathophysiological characteristic of hypertension. Carotid-femoral pulse wave velocity (CF-PWV) is an index of arterial stiffness. Serum uric acid has been found to be involved the development of hypertension. We investigated the relationship between CF-PWV and serum uric acid in subjects with hypertension and hyperuricemia. 651 subjects (M/F 271/380) were divided into four groups, group 1: subjects without hypertension and hyperuricemia; group 2: hypertension subjects without hyperuricemia; group 3: hyperuricemia subjects without hypertension; group 4: subjects with hypertension and hyperuricemia. CF-PWV was measured by Complior apparatus. Results showed that levels of CF-PWV (10.75 ± 2.03 vs. 10.06 ± 1.98 m/s, p < 0.001) and serum uric acid (319.33 ± 80.12 vs. 298.78 ± 74.88 umol/L, p = 0.001) were significantly higher in hypertensive (groups 2 + 4) group than in normotensive (groups 1 + 3) group. CF-PWV was significantly higher in group 4 than group 1, group 2 and group 3 (ANOVA analysis: F = 13.348, p < 0.001; 11.78 ± 2.10 vs. 9.98 ± 1.98, 10.52 ± 1.93, 10.56 ± 1.99 m/s, all p < 0.05, respectively). There was positive correlation between CF-PWV and serum uric acid in entire study group (r = 0.187, p < 0.001), even after adjusting for gender, body mass index, systolic blood pressure (SBP) and diastolic blood pressure (r = 0.100, p = 0.015). Multiple linear regressions showed that SBP, age, benzbromarone, statin and serum uric acid were independent associating factors of CFPWV in all subjects (β = 0.310, p < 0.001; β = 0.330, p < 0.001; β = 0.172, p = 0.002; β = -0.143, p = 0.006; β = 0.126, p = 0.027; respectively). In conclusions, CF-PWV was significantly higher in hypertension subjects with hyperuricemia compared to hypertension without hyperuricemia subjects, and serum uric acid was an independent associating factor of CF-PWV.