Role of urate, xanthine oxidase and the effects of allopurinol in vascular oxidative stress

Adenine-induced animal model of chronic kidney disease: current applications and future perspectives

Chronic kidney disease (CKD) with high morbidity and mortality all over the world is characterized by decreased kidney function, a condition which can result from numerous risk factors, including diabetes, hypertension and obesity. Despite significant advances in our understanding of the pathogenesis of CKD, there are still no treatments that can effectively combat CKD, which underscores the urgent need for further study into the pathological mechanisms underlying this condition. In this regard, animal models of CKD are indispensable. This article reviews a widely used animal model of CKD, which is induced by adenine. While a physiologic dose of adenine is beneficial in terms of biological activity, a high dose of adenine is known to induce renal disease in the organism. Following a brief description of the procedure for disease induction by adenine, major mechanisms of adenine-induced CKD are then reviewed, including inflammation, oxidative stress, programmed cell death, metabolic disorders, and fibrillation. Finally, the application and future perspective of this adenine-induced CKD model as a platform for testing the efficacy of a variety of therapeutic approaches is also discussed. Given the simplicity and reproducibility of this animal model, it remains a valuable tool for studying the pathological mechanisms of CKD and identifying therapeutic targets to fight CKD.

Nephroprotective effect of pioglitazone in a Wistar rat model of adenine‑induced chronic kidney disease

Chronic kidney disease (CKD) is a progressive disease with a high mortality rate and a worldwide prevalence of 13.4%, triggered by various diseases with high incidence. The aim of the present study was to investigate the anti-inflammatory and antifibrotic effect of pioglitazone on kidney in an adenine-induced Wistar rats and the mechanisms possibly involved. CKD was induced in 40 rats. Rats were divided into two groups, which were split into the following sub-groups: i) Therapeutic (pioglitazone administered after renal damage) divided into intact (healthy), adenine (CKD) and adenine/pioglitazone (treatment) and ii) prophylactic (adenine and pioglitazone administered at the same time) split into intact (healthy), adenine (CKD), endogenous reversion (recovery without treatment), adenine/pioglitazone (treatment) and pioglitazone sub-groups. Reverse transcription-quantitative PCR (collagen I, α-SMA and TGF-β), and hematoxylin-eosin, Masson's trichrome and Sirius red staining were performed to measure histological markers of kidney damage, also the serum markers (urea, creatinine and uric acid) were performed, for analyze the effects of pioglitazone. In the adenine/pioglitazone rats of the therapeutic group, renal function parameters such as eGFR increased and serum creatinine decreased from those of untreated rats (CKD), however the renal index, serum urea, abnormalities in renal morphology, inflammatory cells and relative gene expression of collagen I, α-SMA and TGF-β did not change relative to the CKD rats. In adenine/pioglitazone rats, extracellular matrix collagen accumulation was significantly lower than the CKD rats. On the other hand, in adenine/pioglitazone rats of the prophylactic group, the renal index, creatinine, urea, uric acid serum and relative gene expression of collagen I, α-SMA, and TGF-β were significantly lower, as well as the presence of 2,8-dihydroxyadenine crystals, and extracellular matrix collagen compared with CKD rats. In addition, the eGFR in the treatment group was similar to healthy rats, renal morphology was restored, and inflammatory cells were significantly lower. In conclusion, pioglitazone has a nephroprotective effect when administered in the early stages of kidney damage, reducing inflammatory and fibrotic processes and improving glomerular filtration rate. Furthermore, in the late phase of treatment, a tendency to decrease creatinine and increase eGFR was observed.

Imperata cylindrica polysaccharide ameliorates intestinal dysbiosis and damage in hyperuricemic nephropathy

In this study, a combination of adenine and potassium oxonate was utilized to establish a hyperuricemic nephropathy (HN) mouse model, aiming to elucidate the effect through which Imperata Cylindrica polysaccharide (ICPC-a) ameliorates HN. In HN mice, an elevation in the abundance of Erysipelatoclostridium, Enterococcus, Prevotella, and Escherichia-Shigella was observed, whereas Lactobacillus and Bifidobacterium declined. Additionally, the systemic reductions in the levels of acetate, propionate, and butyrate, along with a significant increase in indole content, were noted. HN mice demonstrated intestinal barrier impairment, as evidenced by diminished mRNA expression of ZO-1, Occludin, and Claudin-1 and increased Mmp-9 levels. The pro-inflammatory factors IL-6, IL-17, TNF-α, IFN-γ, and COX-2 were overexpressed. Subsequent gavage intervention with ICPC-a markedly mitigated the inflammatory response and ameliorated colon tissue damage. ICPC-a effectively regulated the abundance of gut microbiota and their metabolites, including short-chain fatty acids (SCFAs), bile acids (BAs), and indole, promoting the correction of metabolic and gut microbiota imbalances in HN mice. These findings underscored the capacity of ICPC-a as a prebiotic to modulate gut microbiota and microbial metabolites, thereby exerting a multi-pathway and multi-targeted therapeutic effect on HN.

Mechanism and use strategy of uric acid-lowering drugs on coronary heart disease

Coronary heart disease (CHD) is a serious cardiovascular illness, for which an elevated uric acid (UA) level presents as a considerable risk factor. This can be treated with UA-lowering drugs such as allopurinol and benzbromarone, which can reduce UA levels by the inhibition of UA production or by promoting its excretion. Such drugs can also be beneficial to CHD in other ways, such as reducing the degree of coronary arteriosclerosis, improving myocardial blood supply and alleviating ventricular remodeling. Different UA-lowering drugs are used in different ways: allopurinol is preferred as a single agent in clinical application, but in absence of the desired response, a combination of drugs such as benzbromarone with ACE inhibitors may be used. Patients must be monitored regularly to adjust the medication regimen. Appropriate use of UA-lowering drugs has great significance for the prevention and treatment of CHD. However, the specific mechanisms of the drugs and individualized drug use need further research. This review article expounds the mechanisms of UA-lowering drugs on CHD and their clinical application strategy, thereby providing a reference for further optimization of treatment.

The role of oxidative stress in aortic dissection: a potential therapeutic target

The incidence of aortic dissection (AD) is steadily increasing, driven by the rising prevalence of chronic conditions such as hypertension and the global aging of the population. Oxidative stress emerges as a pivotal pathophysiological mechanism contributing to the progression of AD. Oxidative stress triggers apoptosis in vascular smooth muscle cells, reshapes the extracellular matrix (ECM), and governs ECM degradation and remodeling, subsequently impacting aortic compliance. Furthermore, oxidative stress not only facilitates the infiltration of macrophages and mononuclear lymphocytes but also disrupts the integral structure and functionality of endothelial cells, thereby inducing endothelial cell dysfunction and furthering the degeneration of the middle layer of the aortic wall. Investigating antioxidants holds promise as a therapeutic avenue for addressing AD.

The Potential of Hemp Extracts to Modify the Course of Oxidative-Stress Related Conditions

The leaves of industrial hemp, which have long been considered as a waste product, have been proven to contain numerous compounds that possess potential biological activity. One of the most interesting groups of compounds present are polyphenolic compounds, which, due to their specific structure, have a pronounced antioxidant and antihyperglycemic potential. This study aimed to detect biological activity, including antioxidant and antihyperglycemic potential, of water and water-alcoholic extracts of five commercially available hemp teas, followed by phytochemical profiling. Hemp aqueous and ethanolic extracts demonstrate potent antioxidant properties. Ethanol extracts are better scavengers of DPPH• and OH•, while aqueous extracts neutralize NO• better. Both types of extracts exhibit antioxidant potential in the catalase test and moderate XOD inhibition. Furthermore, aqueous extracts are potent α-amylase inhibitors, while ethanolic extracts demonstrate stronger anti-α-glucosidase activity, suggesting therapeutic potential for chronic diseases like insulin resistance or diabetes. Further detailed chemical characterization and in vivo studies are needed to validate these findings.

Serum uric acid, body mass index, and cardiovascular diseases: A multiple two-step Mendelian randomization study

BACKGROUND AND AIMS

A number of health issues, including high serum uric acid (SUA) and cardiovascular disease (CVD), have been linked to obesity based on observational evidence, though it's currently unclear how these issues are causally related. In order to determine whether obesity mediates this association, we set out to investigate the causal relationship between SUA, obesity, and CVD.

METHODS AND RESULTS

From publicly available genome-wide association studies, we acquired instrumental variables that had a strong correlation to SUA and body mass index (BMI). We employed multiple two-step Mendelian randomization (MR) analyses, using genetic and clinical data from various publicly available biological databases. The mediating role of BMI was examined through mediation analysis. SUA was genetically correlated with BMI [OR = 1.080, 95% CI: 1.024-1.139, P = 0.005]. There was a positive causal effect of SUA on AF [OR = 0.892, 95% CI: 0.804-0.990, P = 0.032], CAD [OR = 0.942, 95% CI: 0.890-0.997, P = 0.037], and EHT [OR = 1.080, 95% CI: 1.024-1.139, P = 0.005]. Among them, BMI mediated the effects of SUA on AF (42.2%; 95% CI, 35.3%-51.9%), CAD (76.3%; 95% CI, 63.4%-92.0%), and EHT (10.0%; 95% CI, 0%-20.0%).

CONCLUSION

Our research revealed a causal relationship between high SUA exposure and an increased risk of obesity. Additionally, a high SUA level was linked to an increased risk of various CVDs. Given that individuals with high SUA are more likely to be susceptible to AF, CAD, and EHT, attention must be given to their weight status.

Celebrating Versatility: Febuxostat's Multifaceted Therapeutic Application

Febuxostat, initially developed as a xanthine oxidase inhibitor to address hyperuricemia in gout patients, has evolved into a versatile therapeutic agent with multifaceted applications. This review provides a comprehensive overview of febuxostat's mechanism of action, its effectiveness in gout management, its cardiovascular safety profile, renal and hepatic effects, musculoskeletal applications, safety considerations, and emerging research prospects. Febuxostat's primary mechanism involves selective inhibition of xanthine oxidase, resulting in reduced uric acid production. Its pharmacokinetics require personalized dosing strategies based on individual characteristics. In gout management, febuxostat offers a compelling alternative, effectively lowering uric acid levels, relieving symptoms, and supporting long-term control, especially for patients intolerant to allopurinol. Recent studies have demonstrated its cardiovascular safety, and it exhibits minimal hepatotoxicity, making it suitable for those with liver comorbidities. Febuxostat's potential nephroprotective effects and kidney stone prevention properties are noteworthy, particularly for gout patients with renal concerns. Beyond gout, its anti-inflammatory properties hint at applications in musculoskeletal conditions and a broader spectrum of clinical contexts, including metabolic syndrome. Emerging research explores febuxostat's roles in cardiovascular health, neurological disorders, rheumatoid arthritis, and cancer therapy, driven by its anti-inflammatory and antioxidative properties. Future directions include personalized medicine, combination therapies, mechanistic insights, and ongoing long-term safety monitoring, collectively illuminating the promising landscape of febuxostat's multifaceted therapeutic potential.

Structural analysis and attenuates hyperuricemic nephropathy of dextran from the Imperata cylindrica Beauv. var. major (Nees) C. E. Hubb

ICPC-a was from the Imperata cylindrica with a molecular weight of 45 kDa, which was composed of α-D-1,3-Glcp and α-D-1,6-Glcp. The ICPC-a showed thermal stability, maintaining its structural integrity up to 220°C. X-ray diffraction analysis confirmed its amorphous nature, while scanning electron microscopy revealed a layered morphology. ICPC-a significantly ameliorated uric acid stimulation-induced HK-2 cell injury and apoptosis and reduced uric acid levels in mice with hyperuricemic nephropathy. ICPC-a protected against renal injury by inhibiting lipid peroxidation levels, increasing antioxidant damage and defense levels, inhibiting secretion of pro-inflammatory factors, regulating purine metabolism, PI3K-Akt signaling pathway, NF-κB signaling pathway, inflammatory bowel disease, mTOR signaling pathway, and MAPK signaling pathway. These findings indicate that ICPC-a is a promising natural substance with multiple targets, multiple pathways of action, and without toxicity, making it a valuable subject for further research and development.

Discovery and Characterization of Moracin C as an Anti-Gouty Arthritis/Hyperuricemia Candidate by Docking-Based Virtual Screening and Pharmacological Evaluation

In the present study, a natural product database of compounds associated with herbs traditionally verified to treat gout/hyperuricemia/arthritis was constructed. 3D-shape and docking-based virtual screening was conducted. To identify potential xanthine oxidase (XOD) inhibitors in the database, eight compounds with commercial availability were identified as high 3D-shape similarity with febuxostat (1), a known XOD inhibitor. Docking was used to further predict the possible interactions between XOD and these compounds. Moracin C (2), moracin D (3), and isoformononetin (8) exhibited higher docking scores and binding energies than other compounds. In vitro, 2 inhibited XOD with an IC50 value of 0.25 ± 0.14 μM, which is similar to that of 1 (0.16 ± 0.08 μM). In a hyperuricemic mouse model, 5-20 mg/kg 2 exhibited satisfying urate-lowering and XOD inhibitory effects. Compound 2 also exhibited antiarthritis activities. In RAW264.7 cells, 2 at 1-10 μM inhibited the expression of IL-1β and TNF-α induced by MSU. In an acute gouty arthritis model in SD rats, 5-20 mg/kg 2 significantly alleviated the toe swelling, inflammatory response, and dysfunction disorder caused by monosodium urate (MSU). Compound 2 inhibited serum IL-1β and TNF-α cytokines as well as reduced the expression of the NLRP3/ASC/caspase-1 inflammasome in joints. In summary, 2 was an effective compound for the treatment of hyperuricemia/gouty arthritis.

Association between hyperuricemia and hypertension and the mediatory role of obesity: a large cohort study in China

OBJECTIVE

This study aimed to investigate the sex-specific association between hyperuricemia and the risk of hypertension and whether obesity mediates this association.

METHODS

This study included 31,395 (47.0% women) adults without hypertension, cardiovascular disease, or cancer at baseline who completed at least one follow-up annual examination between 2009 and 2016. Cox regression models were performed to calculate hazard ratios and 95% confidence intervals. Mediation analysis was conducted to estimate the effect of body mass index on the association between hyperuricemia and hypertension.

RESULTS

During a median 2.9-year follow-up, hyperuricemia was significantly associated with a higher risk of hypertension (HR 1.15, 95%CI 1.07-1.24 for all participants; HR 1.12, 95%CI 1.03-1.22 for men; and HR 1.23, 95%CI 1.02-1.48 for women) after adjustment for potential confounders. Additional adjustment for body mass index attenuated this association (HR 1.09, 95%CI 1.08-1.10 for all participants; HR 1.07; 95%CI 0.98-1.16 for men; HR 1.18; 95%CI 0.96-1.44 for women). Mediation analysis showed that BMI partially mediated the relationship between hyperuricemia and incident hypertension (indirect effect HR 1.09, 95%CI 1.08-1.10; direct effect: HR 1.08, 95%CI 1.02-1.15). The percentage of the mediation effect was 53.2% (95%CI 37.9-84.5).

CONCLUSION

Hyperuricemia is associated with a risk of hypertension in both sexes, and BMI partially mediates hyperuricemia-related incident hypertension.

Oxidative stress: A target to treat Alzheimer's disease and stroke

Oxidative stress has been established as a well-known pathological condition in several neurovascular diseases. It starts with increased production of highly oxidizing free-radicals (e.g. reactive oxygen species; ROS and reactive nitrogen species; RNS) and becomes too high for the endogenous antioxidant system to neutralize them, which results in a significantly disturbed balance between free-radicals and antioxidants levels and causes cellular damage. A number of studies have evidently shown that oxidative stress plays a critical role in activating multiple cell signaling pathways implicated in both progression as well as initiation of neurological diseases. Therefore, oxidative stress continues to remain a key therapeutic target for neurological diseases. This review discusses the mechanisms involved in reactive oxygen species (ROS) generation in the brain, oxidative stress, and pathogenesis of neurological disorders such as stroke and Alzheimer's disease (AD) and the scope of antioxidant therapies for these disorders.

Lower range of serum uric acid level increases risk of rapid decline of kidney function in young and middle-aged adults: the Yuport Medical Checkup Center Study

BACKGROUND

The effect of low serum uric acid (sUA) levels on kidney function is unclear. This study aimed to clarify the relationship between low sUA levels and the rapid decline in kidney function.

METHODS

We examined the relationship between sUA levels and kidney function decline in health check-up examinees. A total of 10,547 participants were enrolled using data from the Yuport Medical Checkup Center Study between 1998 and 2002 for baseline and data from 2002 to 2006 as the follow-up period in Japan. According to sUA level (mg/dL), we classified the participants into the following six groups: (1) 2.0-2.9 (n = 247), (2) 3.0-3.9 (n = 1457), (3) 4.0-4.9 (n = 2883), (4) 5.0-5.9 (n = 2899), (5) 6.0-6.9 (n = 2010), and (6) 7.0-7.9 (n = 1,051). The relationship between sUA level and rapid decline in estimated glomerular filtration rate (ΔeGFR ≥ 3 mL/min/1.73 m²/year) was examined using a logistic regression model.

RESULTS

During study period (5.4 ± 1.6 years), the incidence of rapid eGFR decline for the respective sUA groups (2.0-2.9, 3.0-3.9, 4.0-4.9, 5.0-5.9, 6.0-6.9, 7.0-7.9) were as follows: 4.5%, 4.0%, 2.4%, 3.3%, 3.1%, 3.4%. The crude and adjusted odds ratios (OR) for rapid eGFR decline were significantly higher in the 2.0-2.9 (OR:1.93 and 1.86) and 3.0-3.9 (OR:1.72 and 1.73) groups than in the 4.0-4.9 groups (reference). Stratified analysis of age differences revealed that the detrimental effect of low sUA was not evident in older adults (age ≥ 65 years).

CONCLUSION

A lower normal sUA level is related to an increased risk for a rapid decline in kidney function.

Investigating a possible causal relationship between maternal serum urate concentrations and offspring birthweight: a Mendelian randomization study

BACKGROUND

Higher urate levels are associated with higher systolic blood pressure (SBP) in adults, and in pregnancy with lower offspring birthweight. Mendelian randomization (MR) analyses suggest a causal effect of higher urate on higher SBP and of higher maternal SBP on lower offspring birthweight. If urate causally reduces birthweight, it might confound the effect of SBP on birthweight. We therefore tested for a causal effect of maternal urate on offspring birthweight.

METHODS

We tested the association between maternal urate levels and offspring birthweight using multivariable linear regression in the Exeter Family Study of Childhood Health (EFSOCH; n = 872) and UK Biobank (UKB; n = 133 187). We conducted two-sample MR to test for a causal effect of maternal urate [114 single-nucleotide polymorphisms (SNPs); n = 288 649 European ancestry] on offspring birthweight (n = 406 063 European ancestry; maternal SNP effect estimates adjusted for fetal effects). We assessed a causal relationship between urate and SBP using one-sample MR in UKB women (n = 199 768).

RESULTS

Higher maternal urate was associated with lower offspring birthweight with similar confounder-adjusted magnitudes in EFSOCH [22 g lower birthweight per 1-SD higher urate (95% CI: -50, 6); P = 0.13] and UKB [-28 g (95% CI: -31, -25); P = 1.8 × 10-75]. The MR causal effect estimate was directionally consistent, but smaller [-11 g (95% CI: -25, 3); PIVW = 0.11]. In women, higher urate was causally associated with higher SBP [1.7 mmHg higher SBP per 1-SD higher urate (95% CI: 1.4, 2.1); P = 7.8 × 10-22], consistent with that previously published in women and men.

CONCLUSION

The marked attenuation of the MR result of maternal urate on offspring birthweight compared with the multivariable regression result suggests previous observational associations may be confounded. The 95% CIs of the MR result included the null but suggest a possible small effect on birthweight. Maternal urate levels are unlikely to be an important contributor to offspring birthweight.

Gender Difference in the Association of Hyperuricemia with Insulin Resistance and beta-cell Function in Nondiabetic Korean Adults: The 2019 Korea National Health and Nutrition Examination Survey

AIMS

This study was conducted to assess the association of uric acid (UA) with the homeostasis model assessment of insulin resistance (HOMA-IR) and beta-cell function (HOMA-B) by gender in nondiabetic Korean adults.

MATERIALS AND METHODS

The study was carried out using data from the 2019 Korean National Health and Nutrition Examination Survey and included nondiabetic Korean men, premenopausal women, and postmenopausal women aged 20 years or older.

RESULTS

First, after adjusted for the related variables (excluding obesity), the prevalence of hyperuricemia (UA ≥ 7.0 mg/dL in men or UA ≥ 6.0 mg/dL in women) was positively associated with the quartiles of HOMA-IR and HOMA-B in men, premenopausal women, and postmenopausal women. Second, when further adjusted for obesity, hyperuricemia was positively associated with the quartiles of HOMA-IR and HOMA-B in men and postmenopausal women but not in premenopausal women. Third, after adjusted for the related variables (including obesity), UA level was positively associated with the quartiles of HOMA-IR and HOMA-B in men and postmenopausal women but not in premenopausal women.

CONCLUSIONS

hyperuricemia is positively associated with insulin resistance and beta-cell function in nondiabetic Korean men and postmenopausal women but not in premenopausal women.

Correlation between Blunted Nocturnal Decrease in Diastolic Blood Pressure and Oxidative Stress: An Observational Study

An impaired nocturnal decrease in diastolic blood pressure (DBP) increases the blood pressure (BP) load, which is a main factor in endothelial dysfunction, atherosclerosis, and arterial stiffness. We aimed to quantify some markers of oxidative stress in hypertensive patients, to compare their levels between individuals with dipper and non-dipper DBP profiles, and to assess their correlation with the nocturnal DBP (nDBP) dipping. It was an observational study that included patients older than 18 years with a diagnosis of essential hypertension who consented to participate. The collected variables were some indices of 24-h ambulatory blood pressure monitoring, demographic, epidemiological, clinical, and laboratory variables. Plasma thiobarbituric acid reactive substances (TBARS) and reduced thiols, together with serum vitamin E, vitamin A, copper (Cu), and zinc (Zn) levels were assessed as oxidative stress markers. We recruited 248 patients with a median age of 56 years (56% women). The percentage of nDBP dipping showed a weak positive correlation with reduced thiol, vitamin E, and vitamin A levels; and a weak negative correlation with Cu levels. We also found a negative correlation between nDBP dipping and the TBARS/Thiol, TBARS/Vitamin E, and TBARS/Vitamin A ratios. After multivariate analysis, we found that increased TBARS/Thiol ratio and serum Cu levels were associated with a higher risk of a non-dipper DBP profile. As in other situations of increased cardiovascular risk, an impaired nDBP decrease may coincide with abnormalities in redox status.

Assessment of the relationship between serum xanthine oxidase levels and type 2 diabetes: a cross-sectional study

Xanthine oxidase (XO) is an enzyme associated with purine metabolism. The relationship between XO levels and type 2 diabetes (T2D) is not clear yet or little is known so far. Therefore, we conducted a cross-sectional study to determine the association of XO levels with T2D in a Bangladeshi adult cohort. A total of 325 participants (234 males and 91 females) were enrolled in the study. The participants were divided into three groups; diabetic (n = 173), prediabetic (n = 35), and non-diabetic control (n = 117). Serum levels of XO were measured by enzyme-linked immunosorbent assay (ELISA) and other biochemical parameters including fasting blood glucose (FBG), serum uric acid (SUA), and lipid profile markers measured by colorimetric methods. Participants with T2D were confirmed according to the definition of the American Diabetic Association. The association between serum XO levels and T2D was determined by logistic regression models. The mean level of serum XO was significantly higher in females (6.0 ± 3.7 U/L) compared to male (4.0 ± 2.8 U/L) participants (p < 0.001). In contrast, males had a higher mean level of SUA (6.1 ± 1.9 mg/dL) than female (4.4 ± 1.9 mg/dL) participants (p < 0.001). The mean level of XO was significantly higher in the diabetic group (5.8 ± 3.6 U/L) compared to the prediabetic (3.7 ± 1.9 U/L) and control (2.9 ± 1.8 U/L) groups (p < 0.001). On the other hand, the mean SUA concentration was significantly lower in the diabetic group than in the other two groups (p < 0.001). A significant increasing trend was observed for FBG levels across the XO quartiles (p < 0.001). A decreasing trend was found for SUA levels in the XO quartiles (p < 0.001). Serum levels of XO and SUA showed a positive and negative correlation with FBG, respectively. In regression analysis, serum XO levels showed an independent association with T2D. In conclusion, this study reports a positive and independent association between XO levels and T2D in Bangladeshi adults. Monitoring serum levels of XO may be useful in reducing the risk of T2D. Further research is needed to determine the underlying mechanisms of the association between elevated XO levels and T2D.

Allopurinol blocks aortic aneurysm in a mouse model of Marfan syndrome via reducing aortic oxidative stress

BACKGROUND

Increasing evidence indicates that redox stress participates in MFS aortopathy, though its mechanistic contribution is little known. We reported elevated reactive oxygen species (ROS) formation and NADPH oxidase NOX4 upregulation in MFS patients and mouse aortae. Here we address the contribution of xanthine oxidoreductase (XOR), which catabolizes purines into uric acid and ROS in MFS aortopathy.

METHODS AND RESULTS

In aortic samples from MFS patients, XOR protein expression, revealed by immunohistochemistry, increased in both the tunicae intima and media of the dilated zone. In MFS mice (Fbn1^C1041G/+), aortic XOR mRNA transcripts and enzymatic activity of the oxidase form (XO) were augmented in the aorta of 3-month-old mice but not in older animals. The administration of the XOR inhibitor allopurinol (ALO) halted the progression of aortic root aneurysm in MFS mice. ALO administrated before the onset of the aneurysm prevented its subsequent development. ALO also inhibited MFS-associated endothelial dysfunction as well as elastic fiber fragmentation, nuclear translocation of pNRF2 and increased 3'-nitrotyrosine levels, and collagen maturation remodeling, all occurring in the tunica media. ALO reduced the MFS-associated large aortic production of H₂O₂, and NOX4 and MMP2 transcriptional overexpression.

CONCLUSIONS

Allopurinol interferes in aortic aneurysm progression acting as a potent antioxidant. This study strengthens the concept that redox stress is an important determinant of aortic aneurysm formation and progression in MFS and warrants the evaluation of ALO therapy in MFS patients.

ROS: Basic Concepts, Sources, Cellular Signaling, and its Implications in Aging Pathways

Reactive oxygen species (ROS) are bioproducts of cellular metabolism. There is a range of molecules with oxidizing properties known as ROS. Despite those molecules being implied negatively in aging and numerous diseases, their key role in cellular signaling is evident. ROS control several biological processes such as inflammation, proliferation, and cell death. The redox signaling underlying these cellular events is one characteristic of the new generation of scientists aimed at defining the role of ROS in the cellular environment. The control of redox potential, which includes the balance of the sources of ROS and the antioxidant system, implies an important target for understanding the cells' fate derived from redox signaling. In this review, we summarized the chemical, the redox balance, the signaling, and the implications of ROS in biological aging.

Allopurinol treatment reduced vascular remodeling and improved vascular functions in monocrotaline-induced pulmonary hypertensive rats

Increased oxidative stress and high uric acid are implicated in the pathogenesis of pulmonary hypertension (PH). This provides opportunity to benefit from drugs like allopurinol which suppresses both contributing factors. Therefore, we aimed to investigate the effects of allopurinol in preventing as well as reversing the pathological changes occurring in monocrotaline (MCT)-induced rat model of PH. Male rats were assigned into three groups based on the follow-up time: 7, 21 and 35 days. Time-matched controls of each group received single injections of MCT (60 mg/kg) intraperitoneally. Test groups consisted of rats who were treated with MCT on day 0 plus oral allopurinol (60 mg/kg) daily for 7 or 21 days. 35-day group received allopurinol for two weeks starting on the 22nd day following MCT injection. At the end of all-time points, rats were killed and basal pulmonary perfusion pressure, Fulton index, pulmonary arterial wall thickness and pulmonary arterial relaxations along with oxidative stress markers (MDA, SOD, XO), NO and uric acid levels were measured in all groups. MCT-injected rats had evidence of raised oxidative stress (high MDA and XO, low SOD levels) which was reversed by allopurinol co-treatment in all-time groups. Marked elevation of uric acid seen in 21- and 35 day-groups was also reversed by allopurinol. Reduced NO levels of 21 and 35 days were unchanged in allopurinol treated groups. Apart from an increase in arterial wall thickening which was maintained in all-time groups, no alterations in other cardiovascular parameters were observed in 7-day group. However, basal lung perfusion pressure and Fulton index significantly increased, while arterial relaxations decreased in 21- and 35-day groups. Co-treatment with allopurinol for 21 days improved these functional alterations, whereas late allopurinol treatment failed to affect them. Our results indicate that early treatment of MCT-induced PH with allopurinol ameliorated the impaired functional characteristics via suppressing the increased oxidative stress and uric acid, while treatment started after progression of the disease had no significant effect.

Exercise Training Ameliorates Renal Oxidative Stress in Rats with Chronic Renal Failure

In patients with chronic kidney disease, exercise training with moderate intensity protects renal function and improves mortality. However, the mechanisms of the renal protective effects of exercise training in chronic kidney disease have not been clarified. This study investigated the effects of exercise training on renal NADPH oxidative and xanthine oxidase, which are major sources of reactive oxygen species, in rats with chronic renal failure. Six-week-old, male Sprague–Dawley rats were divided into the sham operation, 5/6 nephrectomy (Nx)+ sedentary, and Nx+ exercise training groups. The Nx+ exercise training group underwent treadmill running. After 12 weeks, systolic blood pressure, renal function, malondialdehyde, renal NADPH oxidase, and xanthine oxidase were examined. Nx induced hypertension, proteinuria, and renal dysfunction, and exercise training attenuated these disorders. Although the plasma levels of malondialdehyde were not different among the group, urinary levels were increased by Nx and decreased by exercise training. Renal activity and expression of NADPH oxidase and xanthine oxidase were increased by Nx and decreased by exercise training. These results indicate that exercise training attenuates hypertension and renal dysfunction and ameliorates NADPH oxidase and xanthine oxidase in rats with chronic renal failure, suggesting that the reduction of reactive oxygen species generation may be involved in the renal protective effects of exercise training.

Synergistic neuroprotective effect of saikosaponin A and albiflorin on corticosterone-induced apoptosis in PC12 cells via regulation of metabolic disorders and neuroinflammation

BACKGROUND

Saikosaponin A (SSA) and albiflorin (AF) are major bioactive compounds of Radix Bupleuri and Radix Paeoniae alba respectively, which possess antidepressant effects in pharmacological experiments. However, whether SSA and AF have synergistic neuroprotective effects and the synergistic mechanisms are still unknown.

METHODS AND RESULTS

The corticosterone-induced PC12 cells apoptosis model was employed to assess the neuroprotective effects of SSA and AF, and the synergistic effect was analyzed using three mathematical models. Meanwhile, cell metabolomics was used to detect the effects on metabolite regulation of SSA and AF. Furthermore, the key metabolites, metabolic enzymes, and cellular markers were verified by ELISA and Western blotting. The results showed that the combination of SSA and AF has a synergistic neuroprotective effect. Besides, the combination could regulate more metabolites than a single agent and possessed a stronger adjustment effect on metabolites. The TCA cycle was regulated by SSA and AF via improving mitochondrial function. The purine metabolism was regulated by SSA via inhibition xanthine oxidase activity and the glutamate metabolism was regulated by AF via inhibition glutaminase activity. Moreover, the oxidative stress induced by the purine metabolism was attenuated by SSA via a reduction in the ROS level. Additionally, the inflammation induced by the oxidative stress was attenuated by the SSA and AF via inhibition of the NLRP3 protein expression.

CONCLUSIONS

This study for the first time demonstrated the synergistic neuroprotective effects of SSA and AF, and the synergistic mechanisms were involved in metabolic disorders regulation and neuroinflammation inhibition.

A retrospective observational study of serum uric acid and in-hospital mortality in acute type A aortic dissection

There is currently insufficient evidence of correlation between on-admission serum uric acid and in-hospital mortality of patients with acute type A aortic dissection. Thus, this study analysed the relation between serum uric acid and in-hospital deaths in patients with acute type A aortic dissection. A total of 1048 patients with acute type A aortic dissection participated in this study between January 2010 and December 2018. The independent variable was on-admission serum uric acid, whilst the dependent variable was in-hospital deaths. The covariates of the study included patient age, gender, body mass index, smoking status, hypertension, diabetes, Marfan syndrome, bicuspid aortic valve, chronic renal insufficiency, stroke, atherosclerosis, time to presentation, systolic blood pressure, diastolic blood pressure, aortic diameter, aortic regurgitation, abdominal vessel involvement, arch vessel involvement, ejection fraction value, laboratory parameters, symptom, coronary malperfusion, mesenteric malperfusion, cerebral malperfusion, hypotension/shock, cardiac tamponade and operation status. The mean age of the sample was 50.17 ± 11.47 years, with approximately 24.24% of the participants being female. After analysis, it was found that the admission serum uric acid of patients with acute type A aortic dissection was positively correlated with in-hospital death (OR = 1.04, 95% CI 1.02–1.06). Subsequently, a non-linear relationship was determined between admission serum uric acid (point 260 µmol/L) and in-hospital mortality for patients with acute type A aortic dissection. The effect sizes and confidence intervals of the right (serum uric acid > 260 µmol/L) and left (serum uric acid ≤ 260 µmol/L) aspects of the inflection point were 1.04 (1.02–1.05) and 1.00 (0.99–1.02), respectively. Furthermore, subgroup analysis indicated a stable relationship between serum uric acid and in-hospital mortality, whilst an insignificant difference was found for the interactions between different subgroups. Overall, a non-linear correlation was determined between admission serum uric acid and in-hospital mortality of patients with acute type A aortic dissection. When serum uric acid > 260 µmol/L, it showed a positive correlation with in-hospital mortality.

Metabolomics of Arterial Stiffness

Arterial stiffness (AS) is one of the earliest detectable signs of structural and functional alterations of the vessel wall and an independent predictor of cardiovascular events and death. The emerging field of metabolomics can be utilized to detect a wide spectrum of intermediates and products of metabolism in body fluids that can be involved in the pathogenesis of AS. Research over the past decade has reinforced this idea by linking AS to circulating acylcarnitines, glycerophospholipids, sphingolipids, and amino acids, among other metabolite species. Some of these metabolites influence AS through traditional cardiovascular risk factors (e.g., high blood pressure, high blood cholesterol, diabetes, smoking), while others seem to act independently through both known and unknown pathophysiological mechanisms. We propose the term 'arteriometabolomics' to indicate the research that applies metabolomics methods to study AS. The 'arteriometabolomics' approach has the potential to allow more personalized cardiovascular risk stratification, disease monitoring, and treatment selection. One of its major goals is to uncover the causal metabolic pathways of AS. Such pathways could represent valuable treatment targets in vascular ageing.

Reactive Oxygen Species and Oxidative Stress in Vascular-Related Diseases

Oxidative stress (OS) refers to the enhancement of oxidation and the decreased of related antioxidant enzymes activity under pathological conditions, resulting in relatively excess reactive oxygen species (ROS), causing cytotoxicity, which leads to tissue damage and is linked to neurodegenerative diseases, cardiovascular diseases, diabetes, cancers, and many other pathologies. As an important intracellular signaling molecule, ROS can regulate numerous physiological actions, such as vascular reactivity and neuronal function. According to several studies, the uncontrolled production of ROS is related to vascular injury. The growing evidence revealing how traditional risk factors translate into ROS and lead to vasculitis and other vascular diseases. In this review, we sought to mainly discuss the role of ROS and antioxidant mechanisms in vascular-related diseases, especially cardiovascular and common macrovascular diseases.

The chemistry, processing, and preclinical anti-hyperuricemia potential of tea: a comprehensive review

Hyperuricemia is an abnormal purine metabolic disease that occurs when there is an excess of uric acid in the blood, associated with cardiovascular diseases, hypertension, gout, and renal disease. Dietary intervention is one of the most promising strategies for preventing hyperuricemia and controlling uric acid concentrations. Tea (Camellia sinensis) is known as one of the most common beverages and the source of dietary polyphenols. However, the effect of tea on hyperuricemia is unclear. Recent evidence shows that a lower risk of hyperuricemia is associated with tea intake. To better understand the anti-hyperuricemia effect of tea, this review first briefly describes the pathogenesis of hyperuricemia and the processing techniques of different types of tea. Next, the epidemiological and experimental studies of tea and its bioactive compounds on hyperuricemia in recent years were reviewed. Particular attention was paid to the anti-hyperuricemia mechanisms targeting the hepatic uric acid synthase, renal uric acid transporters, and intestinal microbiota. Additionally, the desirable intake of tea for preventing hyperuricemia is provided. Understanding the anti-hyperuricemia effect and mechanisms of tea can better utilize it as a preventive dietary strategy.HighlightsHigh purine diet, excessive alcohol/fructose consumption, and less exercise/sleep are the induction factors of hyperuricemia.Tea and tea compounds showed alleviated effects for hyperuricemia, especially polyphenols.Tea (containing caffeine or not) is not associated with a higher risk of hyperuricemia.Xanthine oxidase inhibition (reduce uric acid production), Nrf2 activation, and urate transporters regulation (increase uric acid excretion) are the potential molecular targets of anti-hyperuricemic effect of tea.About 5 g tea intake per day may be beneficial for hyperuricemia prevention.

Discovery of novel verinurad analogs as dual inhibitors of URAT1 and GLUT9 with improved Druggability for the treatment of hyperuricemia

Verinurad (RDEA3170) is a selective URAT1 inhibitor under investigation for the treatment of gout and hyperuricemia. In an effort to further improve the pharmacodynamics/pharmacokinetics of verinurad and to increase the structural diversity, we designed novel verinurad analogs by introducing a linker (e.g. aminomethyl, amino or oxygen) between the naphthalene and the pyridine ring to increase the flexibility. These compounds were synthesized and tested for their in vitro URAT1-inhibitory activity. Most compounds exhibited potent inhibitory activities against URAT1 with IC₅₀ values ranging from 0.24 μM to 16.35 μM. Among them, compound KPH2f exhibited the highest URAT1-inhibitory activity with IC₅₀ of 0.24 μM, comparable to that of verinurad (IC₅₀ = 0.17 μM). KPH2f also inhibited GLUT9 with an IC₅₀ value of 9.37 ± 7.10 μM, indicating the dual URAT1/GLUT9 targeting capability. In addition, KPH2f showed little effects on OAT1 and ABCG2, and thus was unlikely to cause OAT1/ABCG2-mediated drug-drug interactions and/or to neutralize the uricosuric effects of URAT1/GLUT9 inhibitors. Importantly, KPH2f (10 mg/kg) was equally effective in reducing serum uric acid levels and exhibited higher uricosuric effects in a mice hyperuricemia model, as compared to verinurad (10 mg/kg). Furthermore, KPH2f demonstrated favorable pharmacokinetic properties with an oral bioavailability of 30.13%, clearly better than that of verinurad (21.47%). Moreover, KPH2f presented benign safety profiles without causing hERG toxicity, cytotoxicity in vitro (lower than verinurad), and renal damage in vivo. Collectively, these results suggest that KPH2f represents a novel, safe and effective dual URAT1/GLUT9 inhibitor with improved druggabilities and is worthy of further investigation as an anti-hyperuricemic drug candidate.

Biomarkers of iron status in allopurinol-treated renal stone patients

Limited evidence exists on the effect of xanthine oxidase inhibitors in nephrolithiasis patients on iron status markers, beyond their effects on urate. The aim of this study was to investigate whether allopurinol therapy was associated with a significant impact on parameters related to iron status, in patients with renal stones. Allopurinol treatment was associated with a nonsignificant decline in serum uric acid. There were no significant differences in serum levels of transferrin and ferritin after treatment with allopurinol compared to pre-treatment levels. A non-significant fall in serum levels of haptoglobin was registered. The drug was associated with a significant rise in serum iron levels. Serum uric acid and iron did not show a significant correlation with any parameter in the study. Allopurinol exerted an overall non-significant effect on iron metabolism in nephrolithiasis patients, save for serum iron, this entails lack of untoward effects in populations with-iron related conditions.

Upregulation of hemeoxygenase enzymes HO-1 and HO-2 following ischemia-reperfusion injury in connection with experimental cardiac arrest and cardiopulmonary resuscitation: Neuroprotective effects of methylene blue

Oxidative stress plays an important role in neuronal injuries after cardiac arrest. Increased production of carbon monoxide (CO) by the enzyme hemeoxygenase (HO) in the brain is induced by the oxidative stress. HO is present in the CNS in two isoforms, namely the inducible HO-1 and the constitutive HO-2. Elevated levels of serum HO-1 occurs in cardiac arrest patients and upregulation of HO-1 in cardiac arrest is seen in the neurons. However, the role of HO-2 in cardiac arrest is not well known. In this review involvement of HO-1 and HO-2 enzymes in the porcine brain following cardiac arrest and resuscitation is discussed based on our own observations. In addition, neuroprotective role of methylene blue- an antioxidant dye on alterations in HO under in cardiac arrest is also presented. The biochemical findings of HO-1 and HO-2 enzymes using ELISA were further confirmed by immunocytochemical approach to localize selective regional alterations in cardiac arrest. Our observations are the first to show that cardiac arrest followed by successful cardiopulmonary resuscitation results in significant alteration in cerebral concentrations of HO-1 and HO-2 levels indicating a prominent role of CO in brain pathology and methylene blue during CPR followed by induced hypothermia leading to superior neuroprotection after return of spontaneous circulation (ROSC), not reported earlier.

Relationship between uric acid and lipid accumulation product index by gender in Korean adults: The 2016 Korean National Health and Nutrition Examination Survey

AIMS

The present study assesses the relationship between uric acid (UA) and lipid accumulation product index (LAP) by gender among Korean adults.

METHODS

Data from 5670 subjects (2463 men and 3207 women) in the Korean National Health and Nutrition Examination Survey (KNHANES VII-1) 2016 were analyzed. LAP was divided into four quartiles (Q1-Q4).

RESULTS

There were several key findings. Compared with Q1, in the overall population, the odds ratios (ORs) of hyperuricemia (UA ≥ 7.0 mg/dL in men or UA ≥ 6.0 mg/dL in women) were significantly higher in Q2 [1.847 (95% confidence interval [CI], 1.325-2.575)], Q3 [3.050 (95% CI, 2.216-4.198)], and Q4 of LAP [6.367 (95% CI, 4.658-8.704)]. In men, the ORs of hyperuricemia were significantly higher in Q2 [1.658 (95% CI, 1.162-2.367)], Q3 [2.341 (95% CI, 1.656-3.308)], and Q4 [4.633 (95% CI, 3.290-6.525)] than Q1. In women, the ORs of hyperuricemia were significantly higher in Q2 [2.254 (95% CI, 1.085-4.680)], Q3 [5.402 (95% CI, 2.735-10.668)], and Q4 [11.025 (95% CI, 5.620-21.628)] than Q1. In addition, UA levels were positively associated with LAP level in men (r = 0.218; p < 0.001), women (r = 0.261; p < 0.001), and the overall population (r = 0.260; p < 0.001).

CONCLUSIONS

Hyperuricemia was positively associated with LAP in Korean men and women.

Emerging medical therapies in crush syndrome - progress report from basic sciences and potential future avenues

Crush injury is a disease that is commonly found in victims of earthquakes, debris flows, mine disasters, explosions, terrorist attacks, local wars, and other accidents. The complications that arise due to the crush injury inflicted on victims give rise to crush syndrome (CS). If not treated in time, the mortality rate of CS is very high. The most important measure that can be taken to reduce mortality in such situations is to immediately start treatment. However, the traditional treatment methods such as fluid resuscitation, diuresis, and hemodialysis are not feasible enough to be carried out at the disaster scene. So there is a need for developing new treatments that are efficient and convenient. Because it is difficult to diagnose in the disaster area and reach the treatment equipment and treat on time. It has become a new research needs to be directed into identifying new medical treatment targets and methods using the etiology and pathophysiological mechanisms of CS. In recent years, a large number of new anti-oxidant and anti-inflammatory drug therapies have been shown to be highly efficacious in CS rat/mouse models. Some of them are expected to become specific drugs for the emergency treatment of a large number of patients who may develop CS in the aftermath of earthquakes, wars, and other disasters in the future. Hence, we have reviewed the latest research on the medical therapy of CS as a source for anyone wishing to pursue research in this direction.

Targeting Xanthine Oxidase by Natural Products as a Therapeutic Approach for Mental Disorders

Mental disorders comprise diverse human pathologies, including depression, bipolar affective disorder, schizophrenia, and dementia that affect millions of people around the world. The causes of mental disorders are unclear, but growing evidence suggests that oxidative stress and the purine/adenosine system play a key role in their development and progression. Xanthine oxidase (XO) is a flavoprotein enzyme essential for the catalysis of the oxidative hydroxylation of purines -hypoxanthine and xanthine- to generate uric acid. As a consequence of the oxidative reaction of XO, reactive oxygen species (ROS) such as superoxide and hydrogen peroxide are produced and, further, contribute to the pathogenesis of mental disorders. Altered XO activity has been associated with free radical-mediated neurotoxicity inducing cell damage and inflammation. Diverse studies reported a direct association between an increased activity of XO and diverse mental diseases including depression or schizophrenia. Small-molecule inhibitors, such as the well-known allopurinol, and dietary flavonoids, can modulate the XO activity and subsequent ROS production. In the present work, we review the available literature on XO inhibition by small molecules and their potential therapeutic application in mental disorders. In addition, we discuss the chemistry and molecular mechanism of XO inhibitors, as well as the use of structure-based and computational methods to design specific inhibitors with the capability of modulating XO activity.

Oxidative stress in vascular calcification

Vascular calcification (VC), which is closely associated with significant mortality in cardiovascular disease, chronic kidney disease (CKD), and/or diabetes mellitus, is characterized by abnormal deposits of hydroxyapatite minerals in the arterial wall. The impact of oxidative stress (OS) on the onset and progression of VC has not been well described. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, xanthine oxidases, myeloperoxidase (MPO), nitric oxide synthases (NOSs), superoxide dismutase (SOD) and paraoxonases (PONs) are relevant factors that influence the production of reactive oxygen species (ROS). Furthermore, excess ROS-induced OS has emerged as a critical mediator promoting VC through several mechanisms, including phosphate balance, differentiation of vascular smooth muscle cells (VSMCs), inflammation, DNA damage, and extracellular matrix remodeling. Because OS is a significant regulator of VC, antioxidants may be considered as novel treatment options.

Synthesis, inhibition properties against xanthine oxidase and molecular docking studies of dimethyl N-benzyl-1H-1,2,3-triazole-4,5-dicarboxylate and (N-benzyl-1H-1,2,3-triazole-4,5-diyl)dimethanol derivatives

This study focused on synthesis various dimethyl N-benzyl-1H-1,2,3-triazole-4,5-dicarboxylate and (N-benzyl-1H-1,2,3-triazole-4,5-diyl)dimethanol derivatives under the conditions of green chemistry without the use of solvent and catalysts. Their inhibition properties were also investigated on xanthine oxidase (XO) activity. All dimethanol and dicarboxylate derivatives exhibited significant inhibition activities with IC₅₀ values ranging from 0.71 to 2.25 μM. Especially, (1-(3-bromobenzyl)-1H-1,2,3-triazole-4,5-diyl)dimethanol (5c) and dimethyl 1-(4-chlorobenzyl)-1H-1,2,3-triazole-4,5-dicarboxylate (6 g) compounds were found to be the most promising derivatives on the XO enzyme inhibition with IC₅₀ values 0.71 and 0.73 μM, respectively. Moreover, the double docking procedure was to evaluate compound modes of inhibition and their interactions with the protein (XO) at atomic level. Surprisingly, the docking results showed a good correlation with IC₅₀ [correlation coefficient (R² = 0.7455)]. Also, the docking results exhibited that the 5c, 6f and 6 g have lowest docking scores -4.790, -4.755, and -4.730, respectively. These data were in agreement with the IC₅₀ values. These results give promising beginning stages to assist in the improvement of novel and powerful inhibitor against XO.

Respiratory RNA Viruses: How to Be Prepared for an Encounter with New Pandemic Virus Strains

The characteristics of the biology of influenza viruses and coronavirus that determine the implementation of the infectious process are presented. With provision for pathogenesis of infection possible effects of serine proteinase inhibitors, heparin, and inhibitors of heparan sulfate receptors in the prevention of cell contamination by viruses are examined. It has been determined that chelators of metals of variable valency and antioxidants should be used for the reduction of replicative activity of viruses and anti-inflammatory therapy. The possibility of a pH-dependent impairment of glycosylation of cellular and viral proteins was traced for chloroquine and its derivatives. The use of low-toxicity drugs as part of adjunct therapy increases the effectiveness of synthetic antiviral drugs and interferons and ensures the safety of baseline therapy.

Lycium barbarum polysaccharides protect mice from hyperuricaemia through promoting kidney excretion of uric acid and inhibiting liver xanthine oxidase

CONTEXT

Lycium barbarum L. (Solanaceae) polysaccharides (LBPs) are important active constituents that have demonstrated kidney protection.

OBJECTIVE

This study investigated the effect of LBPs on hyperuricaemia and explored the underlying mechanism in mice.

MATERIALS AND METHODS

Thirty-six C57BL/6 mice were randomly divided into the control group, hyperuricaemia group, allopurinol group (5 mg/kg) and three LBP groups (n = 6). The LBP groups were treated orally with LBPs at 50, 100 and 200 mg/kg body weight for 7 days. We examined the levels of serum uric acid (S_UA) and urinary uric acid (U_UA), as well as xanthine oxidase (XOD) activities. mRNA and protein were quantified by quantitative real-time PCR and Western blotting, respectively.

RESULTS

LBPs treatment (100 and 200 mg/kg) significantly reduced the S_UA levels to 4.83 and 4.48 mg/dL, and markedly elevated the U_UA levels to 4.68 and 5.18 mg/dL (p < 0.05), respectively, while significantly increased the mRNA and protein expression levels of renal organic anti-transporter 1 (OAT1) and organic anti-transporter 3 (OAT3), and markedly decreased the levels of glucose transporter 9 (GLUT9) (p < 0.05). Additionally, the serum XOD activities were reduced to 31.5 and 31.1 mU/mL, and the liver XOD activities were reduced to 80.6 and 75.6 mU/mL after treatment with 100 and 200 mg/kg LBPs (p < 0.01), respectively.

DISCUSSION AND CONCLUSIONS

This study demonstrated the potential role of LBPs in reducing the uric acid level in hyperuricemic mice. A border study population should be evaluated. These results are valuable for the development of new anti-hyperuricaemia agents from LBPs.

Xanthine Oxidase and Transforming Growth Factor Beta-activated Kinase 1: Potential Targets for Gout Intervention

BACKGROUND

Gout, inflammatory arthritis caused by the deposition of monosodium urate crystals into affected joints and other tissues, has become one of the major health problems of today's world. The main risk factor for gout is hyperuricemia, which may be caused by excessive or insufficient excretion of uric acid. The incidence is usually in the age group of 30- 50 years, commonly in males. In developed countries, the incidence of gout ranges from 1 to 4%. Despite effective treatments, there has been an increase in the number of cases over the past few decades.

OBJECTIVE

In recent years, the development of targeted drugs in gout has made significant achievements. The global impact of gout continues to increase, and as a result, the focus of disease-modifying therapies remains elusive. In addition, the characterization of available instrumental compounds is urgently needed to explore the use of novel selective and key protein-ligand interactions for the effective treatment of gout. Xanthine oxidase (XO) is a key target in gout to consider the use of XO inhibitors in patients with mild to moderate condition, however, the costs are high, and no other direct progress has been made. Despite many XO inhibitors, a selective potent inhibitor for XO is limited. Likewise, in recent years, attention has been focused on different strategies for the discovery and development of new selectivity ligands against transforming growth factor beta- activated kinase 1 (TAK1), a potential therapeutic target for gout. Therefore, the insight on human XO structure and TAK1 provides a clue into protein-ligand interactions and provides the basis for molecular modeling and structure-based drug design.

CONCLUSION

In this review, we briefly introduce the clinical characteristics, the development of crystal, inhibitors, and crystal structure of XO and TAK1 protein.

Endothelial dysfunction in neuroprogressive disorders-causes and suggested treatments

BACKGROUND

Potential routes whereby systemic inflammation, oxidative stress and mitochondrial dysfunction may drive the development of endothelial dysfunction and atherosclerosis, even in an environment of low cholesterol, are examined.

MAIN TEXT

Key molecular players involved in the regulation of endothelial cell function are described, including PECAM-1, VE-cadherin, VEGFRs, SFK, Rho GEF TRIO, RAC-1, ITAM, SHP-2, MAPK/ERK, STAT-3, NF-κB, PI3K/AKT, eNOS, nitric oxide, miRNAs, KLF-4 and KLF-2. The key roles of platelet activation, xanthene oxidase and myeloperoxidase in the genesis of endothelial cell dysfunction and activation are detailed. The following roles of circulating reactive oxygen species (ROS), reactive nitrogen species and pro-inflammatory cytokines in the development of endothelial cell dysfunction are then described: paracrine signalling by circulating hydrogen peroxide, inhibition of eNOS and increased levels of mitochondrial ROS, including compromised mitochondrial dynamics, loss of calcium ion homeostasis and inactivation of SIRT-1-mediated signalling pathways. Next, loss of cellular redox homeostasis is considered, including further aspects of the roles of hydrogen peroxide signalling, the pathological consequences of elevated NF-κB, compromised S-nitrosylation and the development of hypernitrosylation and increased transcription of atherogenic miRNAs. These molecular aspects are then applied to neuroprogressive disorders by considering the following potential generators of endothelial dysfunction and activation in major depressive disorder, bipolar disorder and schizophrenia: NF-κB; platelet activation; atherogenic miRs; myeloperoxidase; xanthene oxidase and uric acid; and inflammation, oxidative stress, nitrosative stress and mitochondrial dysfunction.

CONCLUSIONS

Finally, on the basis of the above molecular mechanisms, details are given of potential treatment options for mitigating endothelial cell dysfunction and activation in neuroprogressive disorders.

The past, present and future of RNA respiratory viruses: influenza and coronaviruses

Influenza virus and coronaviruses continue to cause pandemics across the globe. We now have a greater understanding of their functions. Unfortunately, the number of drugs in our armory to defend us against them is inadequate. This may require us to think about what mechanisms to address. Here, we review the biological properties of these viruses, their genetic evolution and antiviral therapies that can be used or have been attempted. We will describe several classes of drugs such as serine protease inhibitors, heparin, heparan sulfate receptor inhibitors, chelating agents, immunomodulators and many others. We also briefly describe some of the drug repurposing efforts that have taken place in an effort to rapidly identify molecules to treat patients with COVID-19. While we put a heavy emphasis on the past and present efforts, we also provide some thoughts about what we need to do to prepare for respiratory viral threats in the future.

Febuxostat attenuates vascular calcification induced by vitamin D3 plus nicotine in rats

This study was undertaken to investigate the possible ameliorative influences of febuxostat (FEB) on vitamin D3 plus nicotine (VDN)-induced vascular calcification (VC) in Wistar rats. VDN rats received a single dose of vitamin D3 (300.000 IU/kg, I.M) and two oral doses of nicotine (25 mg/kg) on day 1. They were then administrated FEB, in two doses (10 and 15 mg/kg/day, orally), or the drug vehicle, for 4 weeks. Age-matched normal rats served as control. At the end of the experiment, body weight, kidney function parameters, serum ionic composition, cardiovascular measures, aortic calcium deposition and aortic levels of oxidative stress markers, interleukin 1β (IL-1β), runt-related transcription factor 2 (Runx2) and osteopontin (OPN) were determined. Aortic immunoexpressions of tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), matrix metalloproteinase-9 (MMP-9) and α-smooth muscle actin (α-SMA) were evaluated. FEB significantly restored body weight loss, ameliorated kidney function and diminished serum disturbances of calcium and phosphorus in VDN rats. Moreover, FEB reduced VDN-induced elevations in aortic calcium deposition, SBP and DBP. FEB (15 mg/kg) markedly decreased left ventricular hypertrophy and bradycardia in VDN group. Mechanistically, FEB dose-dependently improved oxidative damage, decreased levels of IL-1β and Runx2, lessened expression of TNF-α, iNOS and MMP-9 and enhanced expression of OPN and α-SMA in VDN aortas relative to controls. These findings indicate that FEB, mainly at the higher administered dose (15 mg/kg), successfully attenuated VDN-induced VC. FEB may be useful in reducing VC in patients at high risk, including those with chronic kidney disease and diabetes mellitus.

Comparative effectiveness of allopurinol and febuxostat for the risk of atrial fibrillation in the elderly: a propensity-matched analysis of Medicare claims data

AIMS

Gout is associated with a higher risk of atrial fibrillation (AF). Comparative effectiveness of allopurinol or febuxostat for reducing the AF risk is unknown, which was our study's main objective.

METHODS AND RESULTS

We used the 5% Medicare Beneficiary cohort (≥65 years) from 2006 to 2012 to identify people with a new filled prescription for allopurinol or febuxostat, with a baseline period of 365 days without respective medication and without AF. We used 5:1 propensity-matched Cox regression analyses to assess whether allopurinol use differed from febuxostat use regarding the hazard ratio (HR) of incident AF. We found 25 732 eligible episodes in 23 135 beneficiaries. Of these, 2311 incident allopurinol or febuxostat use episodes (9%) ended in incident AF with crude incidence rates of 8.0 and 10.5 per 100 person-years, respectively. In propensity-matched analyses, compared with allopurinol, febuxostat was associated with higher HR of AF, 1.25 [95% confidence interval (CI) 1.05-1.48]. Compared with allopurinol <200 mg/day, febuxostat 80 mg/day was associated with significantly higher HR of AF, 1.62 (95% CI 1.16-2.27), but not febuxostat 40 mg/day or higher allopurinol doses. Compared with 1-180 days of allopurinol use, febuxostat use for 1-180 days was associated with significantly higher HR of AF, 1.36 (95% CI 1.10-1.67), but longer durations were not.

CONCLUSION

Febuxostat was associated with a higher risk of AF compared with allopurinol in older adults. Increased AF risk was noted with febuxostat 80 mg/day dose and was most evident in the first 6 months of use. These findings need replication.

Impact of hyperuricemia on mortality related to aortic diseases: a 3.8-year nationwide community-based cohort study

Despite advances in medicine, aortic diseases (ADs) such as aortic dissection and aortic aneurysm rupture remain fatal with extremely high mortality rates. Owing to the relatively low prevalence of AD, the risk of AD-related death has not yet been elucidated. The aim of the present study was to examine whether hyperuricemia is a risk factor for AD-related mortality in the general population. We used a nationwide database of 474,725 subjects (age 40-75 years) who participated in the annual "Specific Health Check and Guidance in Japan" between 2008 and 2013. There were 115 deaths from aortic dissection and aortic aneurysm rupture during the follow-up period of 1,803,955 person-years. Kaplan-Meier analysis revealed that subjects with hyperuricemia had a higher rate of AD-related death than those without hyperuricemia. Multivariate Cox proportional hazard regression analysis demonstrated that hyperuricemia was an independent risk factor for AD-related death in the general population. The net reclassification index was improved by addition of hyperuricemia to the baseline model. This is the first report to demonstrate that hyperuricemia is a risk factor for AD-related death, indicating that hyperuricemia could be a crucial risk for AD-related death in the general population.

Prevention of Hyperuricemia by Clerodendrum trichotomum Leaf Extract in Potassium Oxonate-Induced Mice

Clerodendrum trichotomum is a folk medicine exhibiting anti-hypertension, anti-arthritis, and anti-rheumatism properties. However, little is known about whether the material might prevent hyperuricemia and associated inflammation. In this study, we explored whether C. trichotomum leaf extract (CTE) prevented hyperuricemia induced by potassium oxonate (PO) in mice. CTE (400 mg/kg body weight) significantly reduced the serum uric acid (UA), blood urea nitrogen (BUN), and serum creatinine levels and increased urine UA and creatinine levels. CTE ameliorated PO-induced inflammation and apoptosis by reducing the levels of relevant proteins in kidney tissues. Also, CTE ameliorated both UA-induced inflammatory response in RAW 263.7 cells and UA-induced cytotoxicity in HK-2 cells. In addition, liver transcriptome analysis showed that CTE enriched mainly the genes for mediating positive regulation of MAPK cascade and apoptotic signaling pathways. Together, the results show that CTE effectively prevents hyperuricemia and associated inflammation in PO-induced mice.

Hyperuricemia is associated with a lower glomerular filtration rate in pediatric sickle cell disease patients

BACKGROUND

Sickle cell nephropathy (SCN) is a progressive disease that contributes significant morbidity and mortality in sickle cell disease (SCD), yet it remains poorly understood. Hyperuricemia negatively impacts renal function in the non-sickle cell population but is understudied in SCD.

METHODS

We performed a cross-sectional analysis of the first 78 pediatric SCD patients enrolled in a cohort study. The mechanism of development of hyperuricemia (defined, serum uric acid (UA) ≥ 5.5 mg/dL) was characterized as a result of either UA overproduction or inefficient renal excretion by the Simkin index and fractional clearance of urate (FCU) equations. Associations between hyperuricemia and albuminuria or estimated glomerular filtration rate (eGFR) were determined by linear regression.

RESULTS

The prevalence of hyperuricemia in this young population (mean age 11.6 ± 3.77 years) was 34.2%. Only 1 hyperuricemic participant overproduced UA by Simkin index, while 62.5% were inefficient renal excretors of UA (FCU < 4%). Hyperuricemia was associated with a significant decrease in average eGFR, -27 ml/min/1.73m² below normouricemia (mean eGFR 151.6 ± 40.32), p = 0.0122. Notably, the previously accepted association between decline of eGFR with age is significantly modified by hyperuricemia stratification, where hyperuricemia explains 44% of the variance in eGFR by age (R² = 0.44, p = 0.0004) and is nonsignificant in normouricemia (R² = 0.07, p = 0.0775).

CONCLUSION

These findings indicate that hyperuricemia may be associated with early eGFR decline in SCN. This association must be further characterized in prospective cohort studies in SCN, and hyperuricemia must be investigated as a potential therapeutic target for SCN.

Association of variability in uric acid and future clinical outcomes of patient with coronary artery disease undergoing percutaneous coronary intervention

BACKGROUND AND AIMS

Hyperuricemia is independently associated with cardiovascular disease (CVD) and is considered to be one of the major risk factors for CVD. However, the impact of inter-visit uric acid (UA) variability on cardiovascular risk remains undetermined.

METHODS

We enrolled 3202 patients with coronary artery disease (CAD), who received successful coronary intervention, in a cohort from Taipei Veterans General Hospital from 2006 to 2015. All post-baseline visits UA measurements using standard deviation (SD) were analyzed to correlate with long-term outcome. The primary outcome was the composite of cardiac death, nonfatal MI, nonfatal stroke (MACE). The secondary event was MACE and hospitalization for heart failure.

RESULTS

During an average 65.06 ± 32.1-month follow-up, there were 66 cardiovascular deaths, 175 nonfatal myocardial infarctions, 64 nonfatal strokes, 287 hospitalizations for heart failure, and 683 revascularization procedures. There was a linear association between high UA SD and future adverse events. Compared to the lowest quartile SD, subjects in the highest quartile SD had a higher risk of MACE (HR: 2.53, 95% CI: 1.78-3.59), myocardial infarction (HR: 2.43, 95% CI: 1.53-3.86), cardiovascular death (HR: 6.45, 95% CI: 2.52-16.55), heart failure-related hospitalization (HR: 3.43, 95% CI: 2.32-5.05), and total major CV events (HR: 2.72, 95% CI: 2.09-3.56). Furthermore, compared to the average achieved on-treatment UA value, increasing UA SD had a stronger association of higher risk of developing MACE (HR: 1.51, 95% CI: 1.36-1.68), myocardial infarction (HR: 1.37, 95% CI: 1.38-1.68), ischemic stroke (HR: 1.43, 95% CI: 1.13-1.82), CV death (HR: 1.77, 95% CI: 1.50-2.11), HF (HR: 1.43, 95% CI: 1.29-1.58), and total major CV events (HR: 1.46, 95% CI: 1.34-1.58).

CONCLUSIONS

High UA variability is associated with a higher risk of developing future cardiovascular events, suggesting the importance of maintaining stable serum UA levels and avoiding large fluctuations in CAD patients after percutaneous coronary intervention (PCI).