Uric acid attenuates nitric oxide production by decreasing the interaction between endothelial nitric oxide synthase and calmodulin in human umbilical vein endothelial cells: A mechanism for uric acid-induced cardiovascular disease development

Unraveling the effects of uric acid on endothelial cells: A global proteomic study

This work aims to understand how normouricemic levels of uric acid can induce endothelial dysfunction seeking global proteomic alterations in Human Umbilical Vein cells (HUVEC). It reveals significant alterations in redox-sensitive and antioxidant proteins, chaperones, and proteins associated with cell migration and adhesion in response to uric acid exposure. Monitoring cellular oxidation with the roGFP2-Grx1 probe proved increased oxidation levels induced by uric acid, which can be attenuated by peroxidasin (PXDN) inhibition, suggesting a regulatory role for PXDN in mitigating oxidative stress induced by uric acid. As a consequence of uric acid oxidation and the formation of reactive intermediate, we identified adducts in proteins (+140 kDa) in a novel post-translation modification named uratylation. Increased misfolded protein levels and p62 aggregation were also found, indicating disturbances in cellular proteostasis. Furthermore, uric acid promoted monocyte adhesion and upregulated ICAM and VCAM protein levels, implicating a pro-inflammatory response in endothelial cells. These findings provide critical insights into the molecular mechanisms underlying vascular damage associated with uric acid.

Hyperuricemia Facilitates Uric Acid-Mediated Vascular Endothelial Cell Damage by Inhibiting Mitophagy

Hyperuricemia remains an elusive factor in the pathogenesis of vascular endothelial injury. This study elucidates the role of hydroxychloroquine (HCQ) in the context of uric acid (UA)-induced vascular endothelial cell damage. Human umbilical vein endothelial cells (HUVECs) were exposed to varying UA concentrations (6 mg/dL to 50 mg/dL) for 48 h, or to 50 mg/dL UA for different time points (6 to 72 h). We observed a concentration- and time-dependent inhibition of cell proliferation, particularly at 40 mg/dL and 50 mg/dL UA. The autophagy marker LC3 exhibited reduced fluorescence intensity post-UA treatment, along with decreased expression of LC3-II/LC3I, beclin1, and p62, indicating impaired autophagy. The mechanistic exploration revealed that HCQ, in conjunction with the mitochondrial autophagy inhibitor Cyclosporine A (CsA), exacerbated the inhibitory effects of UA on HUVEC autophagy. This was evidenced by a further reduction in mitochondrial autophagy-related proteins and diminished fluorescence of LC3-II/LC3-I and Parkin, culminating in suppressed cell proliferation and accelerated cell senescence and apoptosis. Conversely, the co-treatment with the mitochondrial autophagy inducer carbonyl cyanide m-chlorophenyl hydrazine (CCCP) and HCQ mitigated the detrimental effects of UA on HUVEC autophagy. This intervention led to increased expression of PINK1, Parkin, Bnip3, and Nix, along with enhanced fluorescence of LC3-II/LC3-I and Parkin, effectively inhibiting cell senescence and apoptosis while promoting cell proliferation. In conclusion, our findings underscore the pivotal role of HCQ in modulating UA-mediated vascular endothelial cell damage through the inhibition of mitophagy, providing novel insights into the therapeutic potential of targeting HCQ in the management of hyperuricemia-associated vascular complications.

Hyperuricemia-induced complications: dysfunctional macrophages serve as a potential bridge

With the changes in modern life, hyperuricemia (HUA) has become a serious universal health issue, leading to rising morbidity and mortality. Characterized by elevated levels of UA, HUA has become an independent risk factor for gout, chronic kidney disease, insulin resistance, cardiovascular disease, nonalcoholic fatty liver disease, etc. As HUA is a metabolic syndrome, the immune response is likely to play an active role throughout the whole process. Moreover, macrophages, as an indispensable component of the immune system, may serve as a promising target for addressing hyperuricemia-induced inflammation. Along with their precursor cells, monocytes, macrophages play a key role in the pathogenesis of HUA, primarily through three specific aspects, all of which are associated with inflammatory cytokines. The first mechanism involves direct action on urate transporters, such as URAT1 and ABCG2. The second mechanism is the modulation of inflammation, including targeting toll-like receptors (TLRs) and the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome. The third mechanism pertains to the effects on oxidative stress mediators. In this review, we summarize the underlying mechanisms of hyperuricemia, focusing on the effects of macrophages, therapeutic approaches, and clinical trials addressing hyperuricemia-caused dysfunction. Additionally, we highlight directions for future development, aiming to support future theoretical studies.

CRISPR/Cas9 Mediated Deletion of the Uox Gene Generates a Mouse Model of Hyperuricemia with Multiple Complications

Hyperuricemia is a common metabolic disorder with severe complications. We aimed to develop a mouse model for spontaneous hyperuricemia. Uox-/- mouse model was generated on C57BL/6J background by deleting exon 2-4 of Uox using the CRISPR/Cas9 system. The prototypic Uox -/-mice had 5.5-fold increased serum uric acid (1351.04±276.58μmol/L) as compared to the wild type mice (P<0.0001), but died by 4 weeks. After allopurinol (3ug/g) intervention, they all survived > 8 weeks. The serum uric acid was 612.55±146.98μmol/L in the 8-week-old allopurinol-rescued Uox -/-mice, which manifested multiple complications including severe renal insufficiency, hypertension, left ventricular remodeling and systolic dysfunction, aortic endothelial dysfunction, hepatic steatosis and elevated liver enzymes, as well as hyperglycemia and hypercholesteremia. The present Uox-/- mice developed spontaneous hyperuricemia complicated with urate nephropathy, cardiovascular disease and cardiometabolic disorders, and may provide a novel tool to study hyperuricemia associated early-onset cardiovascular disorders in human.

The alarmin, interleukin-33, increases vascular tone via extracellular signal regulated kinase-mediated Ca2+ sensitization and endothelial nitric oxide synthase inhibition

Alarmins are classified by their release from damaged or ruptured cells. Many alarmins have been found to increase vascular tone and oppose endothelium-dependent dilatation (EDD). Interleukin (IL)-33 plays a prominent role in lung injury and can be released during vascular injury and in chronic studies found to be cardioprotective. Our recent work has implicated IL-33 in acute vascular dysfunction following inhalation of engineered nanomaterials (ENM). However, the mechanisms linking IL-33 to vascular tone have not been interrogated. We therefore aimed to determine whether IL-33 directly influenced microvascular tone and endothelial function. Isolated feed arteries and in vivo arterioles from male and female Sprague-Dawley rats were used to determine direct vascular actions of IL-33. Mesenteric feed arteries and arterioles demonstrated reduced intraluminal diameters when treated with increasing concentrations of recombinant IL-33. IL-33 activated extracellular signal regulated kinase (ERK)1/2 of rat aortic smooth muscle cells but not phosphorylation of myosin light chain kinase. This suggested IL-33 may sensitize arterioles to Ca2+-mediated responses. Indeed, IL-33 augmented the myogenic- and phenylephrine-induced vasoconstriction. Additionally, incubation of arterioles with 1 ng IL-33 attenuated ACh-mediated EDD. Mechanistically, in human aortic endothelial cells, we demonstrate that IL-33-mediated ERK1/2 activation leads to inhibitory phosphorylation of serine 602 on endothelial nitric oxide synthase. Finally, we demonstrate that IL-33-ERK1/2 contributes to vascular tone following two known inducers of IL-33; ENM inhalation and the rupture endothelial cells. The present study provides novel evidence that IL-33 increases vascular tone via canonical ERK1/2 activation in microvascular smooth muscle and endothelium. Altogether, it is suggested IL-33 plays a critical role in microvascular homeostasis following barrier cell injury. KEY POINTS: Interleukin (IL)-33 causes a concentration-dependent reduction in feed artery diameter. IL-33 acts on vascular smooth muscle cells to augment Ca2+-mediated processes. IL-33 causes inhibitory phosphorylation of endothelial nitric oxide synthase and opposes endothelium-dependent dilatation. Engineered nanomaterial-induced lung injury and endothelial cell rupture in part act through IL-33 to mediate increased vascular tone.

Hyperuricemia and its related diseases: mechanisms and advances in therapy

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

Uric acid and risk of gestational diabetes mellitus: an observational study and mendelian randomization analysis

OBJECTIVE

Our aim was to explore the relationship between serum uric acid (UA) levels in early pregnancy and the development of gestational diabetes mellitus (GDM), and to further explore whether there is a causal relationship.

METHODS

684 pregnant women with GDM and 1162 pregnant women without GDM participated in this study. 311 pregnant women with GDM and 311 matched controls were enrolled in a 1:1 case-control study. We used conditional logistic regression to explore the relationship between UA levels and the risk of developing GDM. The causal relationship between the two was examined by two-sample Mendelian randomization (MR) analysis.

RESULTS

In the 1:1 matched population, the odds ratio (OR) of developing GDM compared with the extreme tertiles of UA levels was 1.967 (95% confidence interval [CI]: 1.475-2.625; P < 0.001). Restricted cubic spline analyses showed a linear relationship between UA and GDM when UA exceeded 222 µmol/L. GDM and UA levels maintained a statistically significant positive correlation in different stratified regression analyses (P < 0.001). However, no evidence of a causal relationship between uric acid and GDM was found by MR analyses with an OR of 1.06 (95% CI: 0.91-1.25) per unit increase in UA.

CONCLUSION

There is a positive correlation between UA levels in early pregnancy and the subsequent risk of developing GDM. However, no genetic evidence was found to support a cause-effect relationship between UA and GDM.

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.

Uric acid in health and disease: From physiological functions to pathogenic mechanisms

Owing to renal reabsorption and the loss of uricase activity, uric acid (UA) is strictly maintained at a higher physiological level in humans than in other mammals, which provides a survival advantage during evolution but increases susceptibility to certain diseases such as gout. Although monosodium urate (MSU) crystal precipitation has been detected in different tissues of patients as a trigger for disease, the pathological role of soluble UA remains controversial due to the lack of causality in the clinical setting. Abnormal elevation or reduction of UA levels has been linked to some of pathological status, also known as U-shaped association, implying that the physiological levels of UA regulated by multiple enzymes and transporters are crucial for the maintenance of health. In addition, the protective potential of UA has also been proposed in aging and some diseases. Therefore, the role of UA as a double-edged sword in humans is determined by its physiological or non-physiological levels. In this review, we summarize biosynthesis, membrane transport, and physiological functions of UA. Then, we discuss the pathological involvement of hyperuricemia and hypouricemia as well as the underlying mechanisms by which UA at abnormal levels regulates the onset and progression of diseases. Finally, pharmacological strategies for urate-lowering therapy (ULT) are introduced, and current challenges in UA study and future perspectives are also described.

Clinical outcomes of obstructive sleep apnea in patients with acute coronary syndrome in relation to hyperuricemia status

The clinical outcome of obstructive sleep apnea in patients with acute coronary syndrome in relation to hyperuricemia is still unclear. We aimed to explore the clinical prognosis of obstructive sleep apnea in patients with acute coronary syndrome in relation to hyperuricemia status. This was a prospective cohort study. We included consecutively eligible patients with acute coronary syndrome who underwent cardiorespiratory polygraphy between June 2015 and January 2020. According to apnea-hypopnea index ≥ 15 events per hr and serum uric acid level, the population was divided into four groups: hyperuricemia with obstructive sleep apnea; hyperuricemia with non-obstructive sleep apnea; no hyperuricemia with obstructive sleep apnea; and no hyperuricemia with non-obstructive sleep apnea. The primary endpoint was major adverse cardiovascular and cerebrovascular events, including cardiovascular death, myocardial infarction, stroke, ischaemia-driven revascularization, and readmission for unstable angina or heart failure. Spearman correlation analysis and Cox regression model were mainly used to estimate the data. The median follow-up was 2.9 years. Among 1925 patients with acute coronary syndrome, 29.6% had hyperuricemia and 52.6% had obstructive sleep apnea. Uric acid was negatively correlated with minimum arterial oxygen saturation and mean arterial oxygen saturation, and positively correlated with apnea-hypopnea index, oxygen desaturation index and the duration of time with arterial oxygen saturation < 90% (p < 0.001). During 2.9 (1.5, 3.6) years of follow-up, obstructive sleep apnea was associated with an increased risk of major adverse cardiovascular and cerebrovascular events in patients with hyperuricemia (23.5% versus 13.4%; adjusted hazard ratio: 1.834; 95% confidence interval: 1.192-2.821, p = 0.006), but not in patients without hyperuricemia (21.9% versus 19.2%; adjusted hazard ratio: 1.131; 95% confidence interval: 0.880-1.453, p = 0.336). There was a correlation between uric acid levels and sleep respiratory indicators. Obstructive sleep apnea was associated with increased risk of major adverse cardiovascular and cerebrovascular events in patients with acute coronary syndrome with hyperuricemia, but not in patients without hyperuricemia.

Relationship between serum uric acid and estimated glomerular filtration rate in adolescents aged 12-19 years with different body mass indices: a cross-sectional study

Background

Globally, chronic kidney disease (CKD) is a growing public health concern. Serum uric acid (SUA) is an easily detectable and readily available biochemical indicator that has long been recognized as an independent risk factor for CKD. In addition, studies have indicated a potential relationship between SUA and body mass index (BMI). However, studies on the effect of SUA levels on the estimated glomerular filtration rate (eGFR) in adolescents with different BMIs are very rare.

Methods

Weighted multiple regression analysis was used to estimate the independent relationship between SUA and log-transformed eGFR. Additionally, we used a weighted generalized additive model and smooth curve fitting to describe the nonlinear relationships in the subgroup analysis.

Results

First, SUA was negatively associated with log-transformed eGFR even after adjusting for all covariates (β=-0.0177, 95% CI: -0.0203-0.0151, P<0.0001). Second, the results of the stratified analysis found that after adjusting for all covariates, the decrease in log-transformed eGFR due to changes in per SUA levels (Per 1, mg/dL increase) was elevated in female adolescents (β=-0.0177, 95% CI: -0.0216, -0.0138, P<0.0001), adolescents aged 12-15 years (β=-0.0163, 95% CI: -0.0200, -0.0125, P<0.0001) and black (β=-0.0199, 95% CI: -0.0251, -0.0148, P<0.0001) adolescents. Furthermore, we found that adolescents with a higher BMI had higher SUA levels, and the effect of SUA on eGFR was significantly higher in underweight adolescents (β=-0.0386, 95% CI: (-0.0550, -0.0223), P<0.0001).

Conclusion

SUA was negatively associated with the eGFR in adolescents aged 12-19 years. Furthermore, we found for the first time that SUA affects the eGFR differently in adolescents with different BMIs. This effect was particularly significant in underweight adolescents.

Asymptomatic hyperuricaemia in chronic kidney disease: mechanisms and clinical implications

Asymptomatic hyperuricaemia (HU) is considered a pathogenic factor in multiple disease contexts, but a causative role is only proven for the crystalline form of uric acid in gouty arthritis and urate nephropathy. Epidemiological studies document a robust association of HU with hypertension, cardiovascular disease (CVD) and CKD progression, but CKD-related impaired uric acid (UA) clearance and the use of diuretics that further impair UA clearance likely accounts for these associations. Interpreting the available trial evidence is further complicated by referring to xanthine oxidase inhibitors as urate-lowering treatment, although these drugs inhibit other substrates, so attributing their effects only to HU is problematic. In this review we provide new mechanistic insights into the biological effects of soluble and crystalline UA and discuss clinical evidence on the role of asymptomatic HU in CKD, CVD and sterile inflammation. We identify research areas with gaps in experimental and clinical evidence, specifically on infectious complications that represent the second common cause of death in CKD patients, referred to as secondary immunodeficiency related to kidney disease. In addition, we address potential therapeutic approaches on how and when to treat asymptomatic HU in patients with kidney disease and where further interventional studies are required.

Uric acid and risk of pre-eclampsia: results from a large case-control study and meta-analysis of prospective studies

To quantify the association between maternal uric acid levels and pre-eclampsia risk in a large collection of primigravid women. A case-control study (1365 cases of pre-eclampsia and 1886 normotensive controls) was conducted. Pre-eclampsia was defined as blood pressure ≥ 140/90 mmHg and proteinuria ≥ 300 mg/24 h. Sub-outcome analysis included early, intermediate, and late pre-eclampsia. Multivariable analysis for pre-eclampsia and its sub-outcomes was conducted using binary and multinomial logistic regression, respectively. Additionally, a systematic review and meta-analysis of cohort studies measuring uric acid levels < 20 weeks of gestation was performed to rule out reverse causation. There was a positive linear association between increasing uric acid levels and presence of pre-eclampsia. Adjusted odds ratio of pre-eclampsia was 1.21 (95%CI 1.11-1.33) for every one standard deviation increase in uric acid levels. No differences in the magnitude of association were observed between early and late pre-eclampsia. Three studies with uric acid measured < 20 weeks' gestation were identified, with a pooled OR for pre-eclampsia of 1.46 (95%CI 1.22-1.75) for a top vs. bottom quartile comparison. Maternal uric acid levels are associated with risk of pre-eclampsia. Mendelian randomisation studies would be helpful to further explore the causal role of uric acid in pre-eclampsia.

Uric Acid Deteriorates Load-Free Cell Shortening of Cultured Adult Rat Ventricular Cardiomyocytes via Stimulation of Arginine Turnover

Hyperuricemia is a risk factor for heart disease. Cardiomyocytes produce uric acid via xanthine oxidase. The enzymatic reaction leads to oxidative stress in uric-acid-producing cells. However, extracellular uric acid is the largest scavenger of reactive oxygen species, specifically to nitrosative stress, which can directly affect cells. Here, the effect of plasma-relevant concentrations of uric acid on adult rat ventricular cardiomyocytes is analyzed. A concentration- and time-dependent reduction of load-free cell shortening is found. This is accompanied by an increased protein expression of ornithine decarboxylase, the rate-limiting enzyme of the polyamine metabolism, suggesting a higher arginine turnover. Subsequently, the effect of uric acid was attenuated if other arginine consumers, such as nitric oxide synthase, are blocked or arginine is added. In the presence of uric acid, calcium transients are increased in cardiomyocytes irrespective of the reduced cell shortening, indicating calcium desensitization. Supplementation of extracellular calcium or stimulation of intracellular calcium release by β-adrenergic receptor stimulation attenuates the uric-acid-dependent effect. The effects of uric acid are attenuated in the presence of a protein kinase C inhibitor, suggesting that the PKC-dependent phosphorylation of troponin triggers the desensitizing effect. In conclusion, high levels of uric acid stress cardiomyocytes by accelerating the arginine metabolism via the upregulation of ornithine decarboxylase.

Association of Serum Uric Acid with Diabetes in Premenopausal and Postmenopausal Women-A Prospective Cohort Study in Shanghai, China

There have been few prospective studies on the association between serum uric acid (SUA) and the risk of diabetes in women, and there have been few large-scale Chinese studies based on menopause to investigate the association. Therefore, the present study aimed to investigate the above relationship in Chinese female adults without diabetes. Methods: Data from 5743 premenopausal women and 11,287 postmenopausal women aged 20−74 years were obtained from the Shanghai Suburban Adult Cohort and Biobank (SSACB) study conducted in China. Cox regression models were applied to evaluate the association between SUA levels and the risk of diabetes. Restricted cubic spline analysis and stratified analysis on the basis of menopausal status were performed to explore the dose−response association between SUA levels and diabetes. Results: Among 17,030 participants, incidence rates of diabetes were 3.44/1000 person-years in premenopausal and 8.90/1000 person-years in postmenopausal women. The SUA levels in postmenopausal women were higher than that in premenopausal women (p < 0.0001). In Cox regression analysis, after adjusting for confounding factors, for each 10 µmol/L increase in SUA levels, the adjusted HR of diabetes was 1.01 (95% CI: 0.97−1.04) in postmenopausal women, and 1.03 (95% CI: 1.01−1.04) in premenopausal women. Compared with the lowest quartile of SUA levels, the HR (95% CI) of diabetes in the highest quartile was 0.99 (0.55−1.79) in premenopausal women and 1.39 (1.07−1.81) in postmenopausal women. Compared with those without hyperuricemia, the HR (95% CI) for diabetes was 1.89 (0.67−5.31) in premenopausal women with hyperuricemia, and 1.55 (1.19−2.02) in postmenopausal women. Moreover, restricted cubic splines models showed that there was a linear relationship between SUA levels and diabetes risk in premenopausal (p for nonlinear = 0.99) and postmenopausal women (p for nonlinear = 0.95). Furthermore, the restricted cubic spline graph showed that the risk of diabetes in postmenopausal women increased with an increase in SUA levels (p = 0.002). Conclusions: In a cohort of Chinese adult women, SUA levels are associated with diabetes risk in postmenopausal women, but this association was not observed in premenopausal women.

U-shaped association of uric acid to overall-cause mortality and its impact on clinical management of hyperuricemia

Serum uric acid (SUA) is significantly elevated in obesity, gout, type 2 diabetes mellitus, and the metabolic syndrome and appears to contribute to the renal, cardiovascular and pulmonary comorbidities that are associated with these disorders. Most previous studies have focused on the pathophysiologic effects of high levels of uric acid (hyperuricemia). More recently, research has also shifted to the impact of hypouricemia, with multiple studies showing the potentially damaging effects that can be caused by abnormally low levels of SUA. Along with these observations, recent inconclusive data from human studies evaluating the treatment of hyperuricemia with xanthine oxidoreductase (XOR) inhibitors have added to the debate about the causal role of UA in human disease processes. SUA, which is largely derived from hepatic degradation of purines, appears to exert both systemic pro-inflammatory effects that contribute to disease and protective antioxidant properties. XOR, which catalyzes the terminal two steps of purine degradation, is the major source of both reactive oxygen species (O2.-, H2O2) and UA. This review will summarize the evidence that both elevated and low SUA may be risk factors for renal, cardiovascular and pulmonary comorbidities. It will also discuss the mechanisms through which modulation of either XOR activity or SUA may contribute to vascular redox hemostasis. We will address future research studies to better account for the differential effects of high versus low SUA in the hope that this will identify new evidence-based approaches for the management of hyperuricemia.

The Impact of an Elevated Uric Acid Level on the Prevalence of Coronary Artery Disease in Pancreas Transplant Candidates with Type 1 Diabetes: A Cross Sectional Study

Pancreas transplantation is considered a high-risk surgery with cardiovascular complications. Early detection of all potential cardiovascular risk factors can decrease the perioperative risk and improve the pancreas recipients' outcome. The present study aims to evaluate the association between serum uric acid (UA) levels and the prevalence of coronary artery disease (CAD) in patients eligible for pancreas transplantation. We prospectively enrolled 63 consecutive patients with type 1 diabetes (T1D) who underwent cardiological evaluation before pancreas transplantation in our center. Participants underwent clinical evaluation, laboratory assays, and coronary angiography. The median concentration of UA in patients with CAD was significantly higher than in participants without CAD (6.43 (4.93-7.26) vs. 4.41 (3.64-5.49) mg/dL, p = 0.0002). We showed the positive correlation between UA concentration and systolic blood pressure, pulse pressure (PP) and triglycerides (r = 0.271, p = 0.032; r = 0.327, p = 0.009; r = 0.354, p = 0.004, respectively). In a multivariate analysis, the concentration of UA (OR 2.044; 95% CI: 1.261-3.311, p = 0.004) was independently associated with the prevalence of CAD in pancreas transplant candidates with T1D. We demonstrated that elevated UA levels were strongly associated with the high prevalence of CAD in pancreas transplant candidates with T1D. To stratify cardiovascular risk, the measurement of the UA concentration should be considered in all T1D patients qualified for pancreas transplantation.

Chronic Kidney Disease and Arterial Stiffness: A Two-Way Path

The kidney-heart relationship has raised interest for the medical population since its vast and complex interaction significantly impacts health. Chronic kidney disease (CKD) generates vascular structure and function changes, with significant hemodynamic effects. The early arterial stiffening in CKD patients is a consequence of the interaction between oxidative stress and chronic vascular inflammation, leading to an accelerated deterioration of left ventricular function and alteration in tissue perfusion. CKD amplifies the inflammatory cascade's activation and is responsible for altering the endothelium function, increasing the vascular tone, wall thickening, and favors calcium deposits in the arterial wall. Simultaneously, the autonomic imbalance, and alteration in other hormonal systems, also favor the overactivation of inflammatory and fibrotic mediators. Thus, hormonal disarrangement also contributes to structural and functional lesions throughout the arterial wall. On the other hand, a rise in arterial stiffening and volume overload generates high left ventricular afterload. It increases the left ventricular burden with consequent myocardial remodeling, development of left ventricular hypertrophy and, in turn, heart failure. It is noteworthy that reduction in glomerular mass of renal diseases generates a compensatory glomerular filtration overdriven associated with large-arteries stiffness and high cardiovascular events. Furthermore, we consider that the consequent alterations of the arterial system's mechanical properties are crucial for altering tissue perfusion, mainly in low resistance. Thus, increasing the knowledge of these processes may help the reader to integrate them from a pathophysiological perspective, providing a comprehensive idea of this two-way path between arterial stiffness and renal dysfunction and their impact at the cardiovascular level.

Inhibition of dipeptidyl peptidase-4 averts free fatty acids deposition in the hearts of oral estrogen-progestin contraceptive-induced hyperinsulinemic female rats

Free fatty acid (FFA) deposition in non-adipose tissues such as the heart is a characteristic of insulin resistant states which feature hyperinsulinemia and dipeptidyl peptidase-4 (DPP-4) activation. Estrogen-progestin oral contraceptives (OC) treatment reportedly increased DPP-4 activity in rat tissue, and DPP-4 inhibitors have anti-diabetic and anti-inflammatory properties. This study aims to investigate the effects of DPP-4 inhibition on cardiac FFA deposition in estrogen-progestin-treated female rats. From our data, estrogen-progestin OC exposure in female rats led to elevated plasma insulin, cardiac DPP-4 activity, FFA and triglyceride (TG) accumulation, TG/high-density lipoprotein cholesterol (TG/HDL-C) ratio, adenosine deaminase/xanthine oxidase/uric acid pathway (ADA/XO/UA), lipid peroxidation, glycogen synthase activity, and alanine phosphatase; whereas cardiac glucose-6-phosphate dehydrogenase, Na+/K+-ATPase and nitric oxide (NO) were decreased. However, DPP-4 inhibition resulted in decreased plasma insulin, cardiac DPP-4 activity, FFA, TG, TG/HDL-C ratio, and alkaline phosphatase. These were accompanied by reduced ADA/XO/UA pathway, lipid peroxidation, and augmented NO and Na+/K+-ATPase in estrogen-progestin OC-treated rats. DPP-4 inhibition attenuated cardiac lipid deposition accompanied by reduced activity in the ADA/XO/UA pathway in estrogen-progestin OC-treated female rats. DPP-4 is therefore a plausible therapeutic target in cardiometabolic disorders.

Endothelial TRPV4-eNOS coupling as a vital therapy target for treatment of hypertension

BACKGROUND AND PURPOSE

Reduced nitric oxide (NO) level and activity are signs of endothelial dysfunction, which is important in mediating blood pressure up-regulation. Previously, we demonstrated that transient receptor potential channel V4 (TRPV4) could form functional complex with other proteins to mediate vasodilation in the Endothelial cells (ECs). But how TRPV4 interacts with the NO pathway in larger arteries requires further exploration.

EXPERIMENTAL APPROACH

We used single-cell RNA-sequencing to find the CD106⁺ TRPV4^high NOS3^high ECs. The TRPV4-eNOS interaction was verified by co-immunoprecipitation and Immunofluorescence resonance energy transfer (FRET), and their binding site was found by site-directed mutagenesis. Endothelium-specific TRPV4 knockout (TRPV4_EC ^-/- ) mice were used to study the effect of the TRPV4-eNOS interaction on blood pressure. A small molecule, JNc-463 was designed through molecular docking technology.

KEY RESULTS

We uncovered CD106⁺ TRPV4^high NOS3^high ECs in the mouse aorta, which they could regulate vasodilation via a TRPV4-eNOS interaction, and they were essential to regulate blood pressure. The TRPV4-eNOS interaction markedly decreased during the process of hypertension. We further attempted to identify the molecules re-join the TRPV4-eNOS interaction and develop a small-molecule drug, JNc-463, which could increase the TRPV4-eNOS interaction to enhance vasodilation, and exert antihypertensive effects in mice.

CONCLUSION AND IMPLICATIONS

This is the first study integrating single-cell RNA-Seq, single-cell functional study and drug screening in aorta. We identified a subpopulation of CD106⁺ TRPV4^high NOS3^high ECs, in which an impaired TRPV4-eNOS interaction was important in the progress of hypertension and we designed a small molecule, JNc-463 to improve the impaired TRPV4-eNOS interaction in hypertension.

The effects of hyperuricemia on endothelial cells are mediated via GLUT9 and the JAK2/STAT3 pathway

BACKGROUND

Uric acid (UA) transporters mediate the uptake and outflow of UA, and are greatly involved in the control of UA concentrations. Glucose transporter 9 (GLUT9), one of the UA transporters, has been confirmed to be expressed in human umbilical vein endothelial cells (HUVECs). This study aimed to characterize GLUT9's effect on intracellular UA accumulation in HUVECs in a high-UA environment and to explore the mechanism of cellular dysfunction.

METHODS AND RESULTS

HUVECs were treated with UA to establish a model of cellular dysfunction. Then, UA uptake, GLUT9 expression and endothelial nitric oxide synthase (eNOS) and reactive oxygen species (ROS) amounts were measured. UA uptake was concentration- and time-dependent, and UA treatment significantly reduced nitric oxide (NO) levels and eNOS activity. UA also upregulated pro-inflammatory molecules and GLUT9, and increased intracellular ROS amounts in HUVECs. GLUT9 knockdown reduced UA uptake and ROS content, but antioxidant treatment did not reduce GLUT9 expression. To assess the function of JAK2/STAT3 signaling, HUVECs were treated with UA, and the phosphorylation levels of JAK2, STAT3, IL-6 and SOCS3 were increased by a high concentration of UA. In addition, GLUT9 knockdown reduced the phosphorylation of JAK2/STAT3 intermediates and increased p-eNOS amounts.

CONCLUSIONS

GLUT9 mediated the effects of high UA levels on HUVECs by increasing the cellular uptake of UA, activating JAK2/STAT3 signaling, and reduced the production of active eNOS and NO in HUVECs.

Erectile dysfunction in hyperuricemia: A prevalence meta-analysis and meta-regression study

BACKGROUND

Whether and to what extent an association exists between hyperuricemia and erectile dysfunction (ED) has not yet been fully determined.

OBJECTIVE

To define pooled prevalence estimates and correlates of erectile dysfunction in men with hyperuricemic disorders.

MATERIALS AND METHODS

A thorough search of Medline, Scopus, and Cochrane Library databases was performed. Data were combined using random-effects models and the between-study heterogeneity was assessed by Cochrane's Q and I² tests. A funnel plot was used to assess publication bias.

RESULTS

Overall, 8 studies included gave information about 85,406 hyperuricemic men, of whom 5023 complained of erectile dysfunction, resulting in a pooled erectile dysfunction prevalence estimate of 33% (95% Confidence Interval: 13-52%; I² = 99.9%). The funnel plot suggested the presence of a publication bias. At the meta-regression analyses, among the available covariates that could affect estimates, only type 2 diabetes mellitus was significantly associated with a higher prevalence of erectile dysfunction (β = 0.08; 95% Confidence Interval: 0.01, 0.15, p = 0.025). At the sub-group analysis, the pooled erectile dysfunction prevalence decreased to 4% (95% Confidence Interval: 0%-8%) when only the largest studies with the lowest prevalence of type 2 diabetes mellitus were included and increased up to 50% (95% Confidence Interval: 17%-84%) when the analysis was restricted to studies enrolling smaller series with higher prevalence of type 2 diabetes mellitus.

CONCLUSIONS

A not negligible proportion of men with hyperuricemia can complain of erectile dysfunction. While a pathogenetic contribution of circulating uric acid in endothelial dysfunction cannot be ruled out, the evidence of a stronger association between hyperuricemia and erectile dysfunction in type 2 diabetes mellitus points to hyperuricemia as a marker of systemic dysmetabolic disorders adversely affecting erectile function.

Hyperuricemia-induced endothelial insulin resistance: the nitric oxide connection

Hyperuricemia, defined as elevated serum concentrations of uric acid (UA) above 416 µmol L^-1, is related to the development of cardiometabolic disorders, probably via induction of endothelial dysfunction. Hyperuricemia causes endothelial dysfunction via induction of cell apoptosis, oxidative stress, and inflammation; however, it's interfering with insulin signaling and decreased endothelial nitric oxide (NO) availability, resulting in the development of endothelial insulin resistance, which seems to be a major underlying mechanism for hyperuricemia-induced endothelial dysfunction. Here, we elaborate on how hyperuricemia induces endothelial insulin resistance through the disruption of insulin-stimulated endothelial NO synthesis. High UA concentrations decrease insulin-induced NO synthesis within the endothelial cells by interfering with insulin signaling at either the receptor or post-receptor levels (i.e., proximal and distal steps). At the proximal post-receptor level, UA impairs the function of the insulin receptor substrate (IRS) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) in the insulin signaling pathway. At the distal level, high UA concentrations impair endothelial NO synthase (eNOS)-NO system by decreasing eNOS expression and activity as well as by direct inactivation of NO. Clinically, UA-induced endothelial insulin resistance is translated into impaired endothelial function, impaired NO-dependent vasodilation, and the development of systemic insulin resistance. UA-lowering drugs may improve endothelial function in subjects with hyperuricemia.

Far-infrared irradiation inhibits breast cancer cell proliferation independently of DNA damage through increased nuclear Ca2+/calmodulin binding modulated-activation of checkpoint kinase 2

Far-infrared (FIR) irradiation is reported to inhibit cell proliferation in various types of cancer cells; the underlying mechanism, however, remains unclear. We explored the molecular mechanisms using MDA-MB-231 human breast cancer cells. FIR irradiation significantly inhibited cell proliferation and colony formation compared to hyperthermal stimulus, with no alteration in cell viability. No increase in DNA fragmentation or phosphorylation of DNA damage kinases including ataxia-telangiectasia mutated kinase, ataxia telangiectasia and Rad3-related kinase, and DNA-dependent protein kinase indicated no DNA damage. FIR irradiation increased the phosphorylation of checkpoint kinase 2 (Chk2) at Thr68 (p-Chk2-Thr⁶⁸) but not that of checkpoint kinase 1 at Ser345. Increased nuclear p-Chk2-Thr⁶⁸ and Ca²⁺/CaM accumulations were found in FIR-irradiated cells, as observed in confocal microscopic analyses and cell fractionation assays. In silico analysis predicted that Chk2 possesses a Ca²⁺/calmodulin (CaM) binding motif ahead of its kinase domain. Indeed, Chk2 physically interacted with CaM in the presence of Ca²⁺, with their binding markedly pronounced in FIR-irradiated cells. Pre-treatment with a Ca²⁺ chelator significantly reversed FIR irradiation-increased p-Chk2-Thr⁶⁸ expression. In addition, a CaM antagonist or small interfering RNA-mediated knockdown of the CaM gene expression significantly attenuated FIR irradiation-increased p-Chk2-Thr⁶⁸ expression. Finally, pre-treatment with a potent Chk2 inhibitor significantly reversed both FIR irradiation-stimulated p-Chk2-Thr⁶⁸ expression and irradiation-repressed cell proliferation. In conclusion, our results demonstrate that FIR irradiation inhibited breast cancer cell proliferation, independently of DNA damage, by activating the Ca²⁺/CaM/Chk2 signaling pathway in the nucleus. These results demonstrate a novel Chk2 activation mechanism that functions irrespective of DNA damage.

Is microvascular dysfunction a systemic disorder with common biomarkers found in the heart, brain, and kidneys? - A scoping review

Although microvascular dysfunction (MVD) has been well characterized in individual organs as different disease entities, clinical evidence is mounting in support of an underlying systemic process. To address this hypothesis, we systematically searched PubMed and Medline for studies in adults published between 2014 and 2019 that measured blood biomarkers of MVD in three vital organs i.e. brain, heart, and the kidney. Of the 9706 unique articles 321 met the criteria, reporting 49 biomarkers of which 16 were common to the three organs. Endothelial dysfunction, inflammation including reactive oxidation, immune activation, and coagulation were the commonly recognized pathways. Triglyceride, C-reactive protein, Cystatin C, homocysteine, uric acid, IL-6, NT-proBNP, thrombomodulin, von Willebrand Factor, and uric acid were increased in MVD of all three organs. In contrast, vitamin D was decreased. Adiponectin, asymmetric dimethylarginine, total cholesterol, high-density and low-density cholesterol were found to be variably increased or decreased in studies. We review the pathways underlying MVD in the three organs and summarize evidence supporting its systemic nature. This scoping review informs clinicians and researchers in the multi-system manifestation of MVD. Future work should focus on longitudinal investigations to evaluate the multi-system involvement of this disease.

[Association between serum uric acid and subclinical cardiac damage in children with primary hypertension]

OBJECTIVE

To evaluate the condition of subclinical cardiac damage in children with primary hypertension and the association between serum uric acid and subclinical cardiac damage.

METHODS

A retrospective analysis was performed on the medical data of 55 children who were hospitalized and diagnosed with primary hypertension in the Department of Cardiology, Children's Hospital of Soochow University from January 2015 to June 2020. Forty-five healthy children, matched for age and sex, were enrolled as the control group. The two groups were compared in terms of clinical features, laboratory examination, and parameters for left ventricular structure, systolic function, and diastolic function. The correlation of serum uric acid with the parameters for left ventricular structure, systolic function, and diastolic function in children with primary hypertension was analyzed.

RESULTS

Compared with the control group, the hypertension group had significantly higher left ventricular mass (LVM), left ventricular mass index (LVMI), and relative wall thickness (RWT) (P < 0.05). Among the children with primary hypertension, 20 (36%) had left ventricular hypertrophy. The hypertension group had significantly larger left atrial diameter and aortic root diameter than the control group (P < 0.05). The hypertension group had a significantly higher ratio of early diastolic mitral inflow velocity to early diastolic mitral annular velocity than the control group (P < 0.05). The correlation analysis showed that in children with primary hypertension, serum uric acid was positively correlated with LVM (r=0.534, P < 0.01), left atrial diameter (r=0.459, P < 0.01), and aortic root diameter (r=0.361, P=0.010). After adjustment for blood pressure, serum uric acid was still positively correlated with the above parameters (P < 0.05).

CONCLUSIONS

Children with primary hypertension may have subclinical cardiac damage such as left ventricular hypertrophy, left ventricular diastolic dysfunction, left atrial enlargement, and proximal aortic dilation. Elevated serum uric acid is significantly associated with cardiac damage in children with primary hypertension.

Hyperuricemia and the Risk of Heart Failure: Pathophysiology and Therapeutic Implications

The association between hyperuricemia and cardiovascular disease (CVD) has been reported and studied in the past two decades. Xanthine oxidase (XO) induced uric acid (UA) serves as a risk factor and has the independent prognostic and functional impact of heart failure (HF), but whether it plays a positive role in the pathogenesis of HF has remained unclear. Growing evidence suggest the up-regulated XO avtivity and increased production of free oxygen radical (ROS) correspondingly are the core pathogenesis of HF with hyperuricemia, which results in a whole cluster of pathophysiologic cardiovascular effects such as oxidative stress, endothelial dysfunction, vascular inflammation, left ventricular (LV) dysfunction as well as insulin resistance (IR). The use of XO inhibition represents a promising therapeutic choice in patients with HF due to its dual effect of lowering serum UA levels as well as reducing ROS production. This review will discuss the pathophysiologic mechanisms of hyperuricemia with HF, the targeted therapeutic interventions of UA lowering therapies (ULT) with XO inhibition and mechanism underlying beneficial effects of ULT. In addition, the review also summarizes current evidence on the role of ULT in HF and compares CV risk between allopurinol and febuxostat for practical and clinical purposes. Guidelines and implementation of CV risk management in daily practice will be discussed as well.

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.

Sodium-Glucose Cotransporter-2 Inhibitor Immediately Decreases Serum Uric Acid Levels in Type 2 Diabetic Patients

BACKGROUND Sodium-glucose cotransporter-2 (SGLT2) inhibitors are new antihyperglycemic drugs for type 2 diabetes. SGLT2 inhibitors ameliorate cardiovascular morbidity and mortality as well as kidney disease progression by reducing body weight (BW), blood pressure (BP), visceral adiposity, albuminuria, and serum uric acid and blood glucose levels. However, it is not clear which effects are pronounced, and what mechanisms are associated with these effects. MATERIAL AND METHODS This study recruited patients with type 2 diabetes who were prescribed an SGLT2 inhibitor for the first time in our outpatient department. Clinical parameters were measured before and 6 months after the administration of the SGLT2 inhibitor, without the addition of new drugs and dose changes for all prescribed drugs. RESULTS This study recruited 24 patients with type 2 diabetes. No significant differences in BP, glycated hemoglobin (HbA1c) levels, and low-density lipoprotein cholesterol levels were observed after SGLT2 inhibitor administration. In contrast, BW and serum uric acid levels decreased significantly, and the fractional excretion of uric acid (FEUA) increased significantly after administration. While no significant relationships were observed between serum uric acid and FEUA with respect to the percentage changes from baseline values, the percentage changes in serum uric acid levels from baseline were significantly and positively associated with those in serum creatinine levels. CONCLUSIONS Serum uric acid levels were immediately decreased owing to the administration of SGLT2 inhibitor, but BP, blood glucose, and serum lipid levels were unchanged. These changes in serum uric acid levels may be associated with changes in renal function.

Mechanistic Insights of Soluble Uric Acid-related Kidney Disease

Hyperuricemia, defined as the presence of elevated serum uric acid (sUA), could lead to urate deposit in joints, tendons, kidney and other tissues. Hyperuricemia as an independent risk factor was common in patients during the causation and progression of kidney disease. Uric acid is a soluble final product of endogenous and dietary purine metabolism, which is freely filtered in kidney glomeruli where approximately 90% of filtered uric acid is reabsorbed. Considerable studies have demonstrated that soluble uric acid was involved in the pathophysiology of renal arteriolopathy, tubule injury, tubulointerstitial fibrosis, as well as glomerular hypertrophy and glomerulosclerosis. In the review, we summarized the mechanistic insights of soluble uric acid related renal diseases.

Metabolomic characterization of semen from asthenozoospermic patients using ultra-high-performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry

Asthenozoospermia (AS) is a common factor of male infertility, and its pathogenesis remains unclear. The purpose of this study was to investigate the differential seminal plasma metabolic pattern in asthenozoospermic men and to identify potential biomarkers in relation to spermatogenic dysfunction using sensitive ultra-high-performance liquid chromatography-tandem quadruple time-of-flight MS (UHPLC-Q-TOF/MS). The samples of seminal plasma from patients with AS (n = 20) and healthy controls (n = 20) were checked and differentiated by UHPLC-Q-TOF/MS. Compared with the control group, the AS group showed a total of nine significantly different metabolites, including increases in creatinine, uric acid, N6 -methyladenosine (m6 A), uridine, and taurine and decreases in carnitine, nicotinamide, N-acetylputrescine and l-palmitoylcarnitine. By analyzing the correlation among these metabolites and clinical computer-assisted semen analysis reports, we found that m6 A is significantly correlated with not only the four decreased metabolites but also with sperm count, motility, and curvilinear velocity. Furthermore, nicotinamide was shown to correlate with other identified metabolites, indicating its important role in the metabolic pathway of AS. Current results implied that sensitive untargeted seminal plasma metabolomics could identify distinct metabolic patterns of AS and would help clinicians by offering novel cues for discovering the pathogenesis of male infertility.

Distinct uric acid trajectories are associated with incident diabetes in an overweight Chinese population

AIM

To explore uric acid (UA) trajectories in different body mass index (BMI) populations and to determine their associations with incident diabetes.

METHODS

A total of 4566 adults without diabetes in 2011 were enrolled. All participants underwent a medical examination every year until 2016, and were classified into three subgroups based on BMI: non-obese (BMI<24kg/m²); overweight (BMI ≥24kg/m² but<28kg/m²); and obese (BMI ≥28kg/m²). Distinct UA trajectories were identified through group-based trajectory modelling (GBTM). Cox proportional-hazards models were applied to evaluate the associations between UA trajectories and risk of incident diabetes.

RESULTS

UA trajectories were identified in the three BMI subgroups: 'low' (42.4% in non-obese, 22.1% in overweight, 22.0% in obese); 'moderate' (32.5%, 41.1%, 34.8%); 'moderate-high' (18.6%, 29.5%, 30.8%); and 'high' (6.5%, 7.3%, 12.4%). After a 5-year follow-up, 170 (3.7%) participants had developed diabetes. The prevalence of new-onset diabetes increased progressively with the higher UA trajectories in the BMI groups (P values<0.05). Whereas compared with the low trajectory, a significant association between a high UA trajectory and incidence of diabetes was observed only in the overweight population [hazard ratio (HR): 6.95, 95% confidence interval (CI): 1.90-25.45], with no significant associations found in either the non-obese (HR: 0.67, 95% CI: 0.13-3.52) or obese (HR: 0.40, 95% CI: 0.06-2.64) populations, in the fully adjusted model.

CONCLUSION

Higher UA trajectories are significantly associated with an increased risk of incident diabetes, thereby suggesting that monitoring UA trajectories over time may assist in the identification of prediabetes and diabetes, particularly in the overweight population.

Research Advances in the Mechanisms of Hyperuricemia-Induced Renal Injury

Uric acid is the end product of purine metabolism in humans, and its excessive accumulation leads to hyperuricemia and urate crystal deposition in tissues including joints and kidneys. Hyperuricemia is considered an independent risk factor for cardiovascular and renal diseases. Although the symptoms of hyperuricemia-induced renal injury have long been known, the pathophysiological molecular mechanisms are not completely understood. In this review, we focus on the research advances in the mechanisms of hyperuricemia-caused renal injury, primarily on oxidative stress, endothelial dysfunction, renal fibrosis, and inflammation. Furthermore, we discuss the progress in hyperuricemia management.

Soluble Uric Acid Is an Intrinsic Negative Regulator of Monocyte Activation in Monosodium Urate Crystal-Induced Tissue Inflammation

Although monosodium urate (MSU) crystals are known to trigger inflammation, published data on soluble uric acid (sUA) in this context are discrepant. We hypothesized that diverse sUA preparation methods account for this discrepancy and that an animal model with clinically relevant levels of asymptomatic hyperuricemia and gouty arthritis can ultimately clarify this issue. To test this, we cultured human monocytes with different sUA preparation solutions and found that solubilizing uric acid (UA) by prewarming created erroneous results because of UA microcrystal contaminants triggering IL-1β release. Solubilizing UA with NaOH avoided this artifact, and this microcrystal-free preparation suppressed LPS- or MSU crystal-induced monocyte activation, a process depending on the intracellular uptake of sUA via the urate transporter SLC2A9/GLUT9. CD14⁺ monocytes isolated from hyperuricemic patients were less responsive to inflammatory stimuli compared with monocytes from healthy individuals. Treatment with plasma from hyperuricemic patients impaired the inflammatory function of CD14⁺ monocytes, an effect fully reversible by removing sUA from hyperuricemic plasma. Moreover, Alb-creERT2;Glut9 ^lox/lox mice with hyperuricemia (serum UA of 9-11 mg/dl) showed a suppressed inflammatory response to MSU crystals compared with Glut9 ^lox/lox controls without hyperuricemia. Taken together, we unravel a technical explanation for discrepancies in the published literature on immune effects of sUA and identify hyperuricemia as an intrinsic suppressor of innate immunity, in which sUA modulates the capacity of monocytes to respond to danger signals. Thus, sUA is not only a substrate for the formation of MSU crystals but also an intrinsic inhibitor of MSU crystal-induced tissue inflammation.

Optimization of Microenvironments Inducing Differentiation of Tonsil-Derived Mesenchymal Stem Cells into Endothelial Cell-Like Cells

BACKGROUND

Stem cell engineering is appealing consideration for regenerating damaged endothelial cells (ECs) because stem cells can differentiate into EC-like cells. In this study, we demonstrate that tonsil-derived mesenchymal stem cells (TMSCs) can differentiate into EC-like cells under optimal physiochemical microenvironments.

METHODS

TMSCs were preconditioned with Dulbecco's Modified Eagle Medium (DMEM) or EC growth medium (EGM) for 4 days and then replating them on Matrigel to observe the formation of a capillary-like network under light microscope. Microarray, quantitative real time polymerase chain reaction, Western blotting and immunofluorescence analyses were used to evaluate the expression of gene and protein of EC-related markers.

RESULTS

Preconditioning TMSCs in EGM for 4 days and then replating them on Matrigel induced the formation of a capillary-like network in 3 h, but TMSCs preconditioned with DMEM did not form such a network. Genome analyses confirmed that EGM preconditioning significantly affected the expression of genes related to angiogenesis, blood vessel morphogenesis and development, and vascular development. Western blot analyses revealed that EGM preconditioning with gelatin coating induced the expression of endothelial nitric oxide synthase (eNOS), a mature EC-specific marker, as well as phosphorylated Akt at serine 473, a signaling molecule related to eNOS activation. Gelatin-coating during EGM preconditioning further enhanced the stability of the capillary-like network, and also resulted in the network more closely resembled to those observed in human umbilical vein endothelial cells.

CONCLUSION

This study suggests that under specific conditions, i.e., EGM preconditioning with gelatin coating for 4 days followed by Matrigel, TMSCs could be a source of generating endothelial cells for treating vascular dysfunction.

Is Hyperuricemia, an Early-Onset Metabolic Disorder, Causally Associated with Cardiovascular Disease Events in Han Chinese?

BACKGROUND

Serum uric acid (SUA) has gradually been recognized as a potential risk factor for cardiovascular disease (CVD). However, whether the relationship is causal remains controversial.

METHODS

We employed two methods to demonstrate the importance of SUA in CVD development. First, we examined the onset sequence of hyperuricemia in relation to five cardiometabolic (CM) diseases. Second, we conducted a Mendelian randomization (MR) study to causally infer the relationship between SUA and CVD. The information collected from the Cardiovascular Disease Risk Factors Two-Township Study (CVDFACTS) and Taiwan Biobank was used, respectively.

RESULTS

The onset sequence study showed that hyperuricemia and hypo-alpha-lipoproteinemia (low HDL-C) have earlier ages of onset than other CM diseases. For the MR analysis, the high weighted genetic risk score (WGRS) group had a significantly increased cumulative lifetime risk of CVD compared with the low WGRS group (OR = 1.62, (1.17-2.23), P = 0.003). Sensitivity analysis using the WGRS derived from other populations' SUA-influential SNPs revealed similar results.

CONCLUSIONS

We showed that hyperuricemia is an earlier-onset metabolic disorder than hypertension, hypertriglyceridemia, and diabetes mellitus, indicating that high SUA plays an upstream role in CM development. Moreover, our MR study results support the idea that hyperuricemia may play a causal role in CVD development. Further validation studies in more populations are needed.

Arterial Stiffness in the Heart Disease of CKD

CKD frequently leads to chronic cardiac dysfunction. This complex relationship has been termed as cardiorenal syndrome type 4 or cardio-renal link. Despite numerous studies and reviews focused on the pathophysiology and therapy of this syndrome, the role of arterial stiffness has been frequently overlooked. In this regard, several pathogenic factors, including uremic toxins (i.e., uric acid, phosphates, endothelin-1, advanced glycation end-products, and asymmetric dimethylarginine), can be involved. Their effect on the arterial wall, direct or mediated by chronic inflammation and oxidative stress, results in arterial stiffening and decreased vascular compliance. The increase in aortic stiffness results in increased cardiac workload and reduced coronary artery perfusion pressure that, in turn, may lead to microvascular cardiac ischemia. Conversely, reduced arterial stiffness has been associated with increased survival. Several approaches can be considered to reduce vascular stiffness and improve vascular function in patients with CKD. This review primarily discusses current understanding of the mechanisms concerning uremic toxins, arterial stiffening, and impaired cardiac function, and the therapeutic options to reduce arterial stiffness in patients with CKD.

Uric Acid and Its Correlation with Various Metabolic Parameters: A Population-Based Study

INTRODUCTION

Uric acid, apparently an inert waste product, was found to have association with various metabolic disorders. The data regarding prevalence of serum uric acid (SUA) abnormalities and its correlation with other anthropo-metabolic parameters, however, are scanty.

MATERIALS AND METHODS

In all, 405 participants from a rural area were investigated for various metabolic parameters including uric acid. SUA level was evaluated for having any correlation with other anthropometric and metabolic disorders like obesity, dyslipidemia, metabolic syndrome (MetS), hypertension, calcium and vitamin D abnormalities, liver function, and glycemic alterations. Lean MetS is defined as those having waist criteria below the region specific waist criteria and even then satisfying the definition of MetS as per the National Cholesterol Education Program (NCEP) ATP-III (Adult Treatment Panel) criteria.

RESULTS

The mean uric acid was 4.2 mg/dL (±1.35), with 4.9 mg/dL (±1.28) for males and 3.7 mg/dL (±1.14) for females. Thirteen of 405 people (3.2%) found to have uric acid level of more than 7.0 mg/dL, and eight people out of 405 (2.0%) had hypouricemia. SUA showed correlation with age, blood pressure, and the anthropometric parameters for obesity, for example, weight, body mass index, waist circumference, waist hip ratio, waist height ratio, fasting insulin, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol, and triglycerides. However, fasting glucose, calcium, phosphate, 25-hydroxy vitamin D3, and iPTH did not show any correlation with the SUA level. Compared to the healthy population, SUA level was elevated in MetS as defined by International Diabetes Federation (IDF) criteria. However, the SUA in healthy population was not significantly different from the Lean MetS, and SUA of Lean MetS was not significantly different from Obese MetS.

CONCLUSION

SUA is elevated in MetS compared to the normal population. However, SUA in Lean MetS is not different from Obese MetS.

Elevated serum uric acid affects myocardial reperfusion and infarct size in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

AIMS

Elevated serum uric acid (eSUA) was associated with unfavorable outcome in patients with ST-segment elevation myocardial infarction (STEMI). However, the effect of eSUA on myocardial reperfusion injury and infarct size has been poorly investigated. Our aim was to correlate eSUA with infarct size, infarct size shrinkage, myocardial reperfusion grade and long-term mortality in STEMI patients undergoing primary percutaneous coronary intervention.

METHODS

We performed a post-hoc patients-level analysis of two randomized controlled trials, testing strategies for myocardial ischemia/reperfusion injury protection. Each patient underwent acute (3-5 days) and follow-up (4-6 months) cardiac magnetic resonance. Infarct size and infarct size shrinkage were outcomes of interest. We assessed T2-weighted edema, myocardial blush grade (MBG), corrected Thrombolysis in myocardial infarction Frame Count, ST-segment resolution and long-term all-cause mortality.

RESULTS

A total of 101 (86.1% anterior) STEMI patients were included; eSUA was found in 16 (15.8%) patients. Infarct size was larger in eSUA compared with non-eSUA patients (42.3 ± 22 vs. 29.1 ± 15 ml, P = 0.008). After adjusting for covariates, infarct size was 10.3 ml (95% confidence interval 1.2-19.3 ml, P = 0.001) larger in eSUA. Among patients with anterior myocardial infarction the difference in delayed enhancement between groups was maintained (respectively, 42.3 ± 22.4 vs. 29.9 ± 15.4 ml, P = 0.015). Infarct size shrinkage was similar between the groups. Compared with non-eSUA, eSUA patients had larger T2-weighted edema (53.8 vs. 41.2 ml, P = 0.031) and less favorable MBG (MBG < 2: 44.4 vs. 13.6%, P = 0.045). Corrected Thrombolysis in myocardial infarction Frame Count and ST-segment resolution did not significantly differ between the groups. At a median follow-up of 7.3 years, all-cause mortality was higher in the eSUA group (18.8 vs. 2.4%, P = 0.028).

CONCLUSION

eSUA may affect myocardial reperfusion in patients with STEMI undergoing percutaneous coronary intervention and is associated with larger infarct size and higher long-term mortality.

Aberrant Promoter Hypomethylation of Sortilin 1: A Moyamoya Disease Biomarker

BACKGROUND AND PURPOSE

The pathogenesis of moyamoya disease (MMD) remains poorly understood, and no reliable molecular biomarkers for MMD have been identified to date. The present study aimed to identify epigenetic biomarkers for use in the diagnosis of MMD.

METHODS

We performed integrated analyses of gene expression profiles and DNA methylation profiles in endothelial colony forming cells (ECFCs) from three patients with MMD and two healthy individuals. Candidate gene mRNA expression and DNA methylation status were further validated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and pyrosequencing analysis of an expanded ECFC sample set from nine patients with MMD and ten controls. We evaluated the diagnostic accuracy of the potential biomarkers identified here using receiver operating characteristic curve analyses and further measured major angiogenic factor expression levels using a tube formation assay and RT-qPCR.

RESULTS

Five candidate genes were selected via integrated analysis; all five were upregulated by hypomethylation of specific promoter CpG sites. After further validation in an expanded sample set, we identified a candidate biomarker gene, sortilin 1 (SORT1). DNA methylation status at a specific SORT1 promoter CpG site in ECFCs readily distinguished patients with MMD from the normal controls with high accuracy (area under the curve 0.98, sensitivity 83.33%, specificity 100%). Furthermore, SORT1 overexpression suppressed endothelial cell tube formation and modulated major angiogenic factor and matrix metalloproteinase-9 expression, implying SORT1 involvement in MMD pathogenesis.

CONCLUSION

s Our findings suggest that DNA methylation status at the SORT1 promoter CpG site may be a potential biomarker for MMD.

Levels of uric acid in erectile dysfunction of different aetiology

Erectile dysfunction is a common disease characterized by endothelial dysfunction. The aetiology of ED is often multifactorial but evidence is being accumulated in favor of the proper function of the vascular endothelium that is essential to achieving and maintaining penile erection. Uric acid itself causes endothelial dysfunction via decreased nitric oxide production. This study aims to evaluate the serum uric acid (SUA) levels in 180 ED patients, diagnosed with the International Index of Erectile Function-5 (IIEF-5) and 30 non-ED control. Serum uric acid was analyzed with a commercially available kit using ModularEVO (Roche, Monza, Italy). Within-assay and between-assay variations were 3.0% and 6.0%, respectively. Out of the ED patients, 85 were classified as arteriogenic (A-ED) and 95 as non-arteriogenic (NA-ED) with penile-echo-color-Doppler. Uric acid levels (median and range in mg/dL) in A-ED patients (5.8, 4.3-7.5) were significantly higher (p < .001) than in NA-ED patients (4.4, 2.6-5.9) and in control group (4.6, 3.1-7.2). There was a significant difference (p < .001) between uric acid levels in patients with mild A-ED (IIEF-5 16-20) and severe/complete A-ED (IIEF-5 ≤ 10) that were 5.4 (range 4.3-6.5) mg/dL and 6.8 (range 6.4-7.2) mg/dL, respectively. There was no difference between the levels of uric acid in patients with different degree of NA-ED. Our findings reveal that SUA is a marker of ED but only of ED of arteriogenic aetiology.

Role of Uric Acid in Semen

Since 1963, various research studies and reports have demonstrated the role of uric acid (2,6,8-trihydroxypurine), an end product of adenosine and guanosine catabolism, on semen quality and sperm function. However, this effect has not yet been collectively discussed, even though uric acid has been a well-recognized constituent in semen. Here, we systematically and comprehensively discuss and summarize the role/effect of uric acid in semen quality by searching the main databases for English language articles considering this topic. Additionally, certain significant and relevant papers were considered to support discussions and perceptions. In conclusion, uric acid contributes to maintaining and enhancing sperm motility, viability, and morphology; therefore, protecting sperm function and fertilizing ability. This contribution is performed mainly by neutralizing the damaging effect of oxidizing (e.g., endogenous free radicals and exogenous toxins) and nitrating agents and enhancing certain bioactive enzymes in spermatozoa. In contrast, high levels of uric acid may induce adverse effects to sperm function, at least in part, by reducing the activity of vital enzymes in spermatozoa. However, further research, mainly clinical, is still required to fully explore the role/effect of uric acid in semen.

Gender Differences in the Association between Serum Uric Acid and Prediabetes: A Six-Year Longitudinal Cohort Study

This study aimed to examine gender differences in the association between serum uric acid (SUA) and the risk of prediabetes in a longitudinal cohort. A total of 8237 participants in the Beijing Health Management Cohort study were recruited and surveyed during 2008⁻2009, and followed up in 2011⁻2012 and 2014⁻2015 surveys. Generalized estimating equation (GEE) models were used to evaluate the association between SUA and prediabetes. Furthermore, subgroup analyses assessed the primary outcome according to status of abdominal obesity, age and status of hypertension. During six years of follow-up, we identified 1083 prediabetes events. The GEE analyses confirmed and clarified the association between SUA and prediabetes (RR = 1.362; 95% CI = 1.095⁻1.696; p = 0.006) after adjusting for other potential confounders, especially in females (RR = 2.109; 95% CI = 1.329⁻3.347; p = 0.002). In addition, this association was stronger in the subgroup of females aged ≥48 years old (RR = 2.384; 95% CI = 1.417⁻4.010; p = 0.001). The risk for prediabetes increased significantly with increasing SUA for females in the Chinese population. This association was strongly confirmed in older females aged ≥48 years old rather than in younger females, which may provide clues for pathogenic mechanisms of gender differences in the association between SUA and prediabetes.

Determinants of retinal microvascular features and their relationships in two European populations

Supplemental Digital Content is available in the text

Objectives:

To examine factors influencing retinal vasculature in two environmentally contrasted, cross-sectional studies of adult participants of European descent and to estimate the extent and specificity of genetic contributions to each retinal vasculature feature.

Methods:

Retinal images from 1088 participants in the Orkney Complex Disease Study and 387 in the CROATIA-Korčula study, taken using the same nonmydriatic camera system and graded by the same person, were evaluated. Using general linear models, we estimated the influence of an extensive range of systemic risk factors, calculated retinal traits heritabilities and genetic correlations.

Main results:

Systemic covariates explained little (<4%) of the variation in vessel tortuosity, substantially more (>10%, up to 31.7%) of the variation in vessel width and monofractal dimension. Suggestive not well trodden associations of biological interest included that of urate, tissue plasminogen activator and cardiac PR interval with arteriolar narrowing, that of carotid intima–media thickness with less-tortuous arterioles and of cardiac QT interval with more tortuous venules. The genetic underpinning of tortuosity is largely distinct from that of the other retinal vascular features, whereas that of fractal dimension and vessel width greatly overlaps. The previously recognized influence of ocular axial length on vessel widths was high and can be expected to lead to artefactual genetic associations [genetic correlation with central retinal arteriolar equivalent: −0.53 (standard error 0.11)]. The significant genetic correlation between SBP and central retinal arteriolar equivalent, −0.53 (standard error 0.22) (after adjusting for age, sex and axial length of the eye), augurs more favourably for the discovery of genetic variants relevant to vascular physiology.

Interaction between body mass index and serum uric acid in relation to blood pressure in community-dwelling Japanese men

Background

Few data is available on the association between body mass index (BMI), serum uric acid (SUA) levels and blood pressure (BP) categories in the disease continuum, when efforts for its prevention may be applicable.

Methods

We performed a cross-sectional study to examine the association between BMI, SUA and BP in a community-dwelling sample of Japanese men. Individuals not on antihypertensive and uric acid lowering medications, and aged 50 to 90 years [817men aged 66 ± 9 (mean ± standard deviation) years] were recruited for the survey during a community based annual medical check-up. The main outcome was the presence of prehypertension [systolic BP (SBP) 120-139 mmHg and/or diastolic BP (DBP) 80-89 mmHg] and hypertension [SBP ≥ 140 and /or DBP ≥ 90].

Results

In participants with a BMI of < 21.0 kg/m², increased SUA levels were positively associated with SBP and DBP, but in those with a BMI of ≥ 21.0 kg/m², increased SUA levels were negatively associated with SBP and DBP. The interaction between BMI and SUA as well as BMI and SUA was a significant and independent determinant for both SBP (β = − 1.125, p = 0.001) and DBP (β = − 0.995, p = 0.005). Among participants, the respective prevalence of normotension, prehypertension, and hypertension was 19.5% and 53.7%, and 19.8%. The prevalence of normotension and prehypertension decreased with increasing BMI and the prevalence of hypertension increased with increasing BMI. In participants with a BMI ≥ 21.0 kg/m², the adjusted-odds ratio of SUA for hypertension was 0.75 (95% CI, 0.59-0.95) compared with normotension and 0.82 (0.70-0.96) compared with prehypertension. In those with a BMI of < 21.0 kg/m², these associations were not shown.

Conclusion

BMI may modify the association between SUA and blood pressure status among community-dwelling men.

Chronic hyperuricemia impairs blood flow recovery in the ischemic hindlimb through suppression of endothelial progenitor cells

Objective

Chronic hyperuricemia is associated with cardiovascular disease, but its impact on endothelial progenitor cells (EPC) and ischemia-induced neovascularization remains unclear. Herein we investigated whether chronic hyperuricemia could impede blood flow recovery in response to tissue ischemia by suppression of EPC.

Methods

Human EPC were isolated and cultured in a high-level uric acid medium for functional testing. Cell proliferation, nitric oxide (NO) production and apoptosis assay were examined. A chronic hyperuricemia mouse model was established by potassium oxonate treatment and/or a high-level uric acid diet to evaluate the actions of chronic hyperuricemia on ischemia-induced blood flow recovery. After 4 weeks of drug treatment, hindlimb ischemia surgery was performed in the control and hyperuricemia mice. Blood flow recovery was followed up every week before and after ischemic surgery using a laser Doppler Perfusion Imager System. The circulating EPC number in the peripheral blood was determined by flow cytometry (Sca-1⁺/Flk-1⁺).

Results

Incubation with a high-level uric acid medium (10 mg/dL) significantly suppressed EPC proliferation, reduced NO production, and lessened phosphorylation of Akt and eNOS. Moreover, EPC treated with high-level uric acid increased reactive oxygen species production, promoted cellular apoptosis and senescence, and also inhibited EPC tube formation. Four weeks after hindlimb ischemia surgery, the chronic hyperuricemia mice had significantly reduced tissue reperfusion, EPC mobilization, and impaired neovascularization in the ischemic hindlimbs compared with the control mice.

Conclusions

Chronic hyperuricemia impaired blood flow recovery and EPC mobilization in response to tissue ischemia, and these effects could have occurred through suppression of EPC.

Rice Bioactive Peptide Binding with TLR4 To Overcome H2O2-Induced Injury in Human Umbilical Vein Endothelial Cells through NF-κB Signaling

Reactive oxygen species-induced vessel endothelium injury is crucial in cardiovascular diseases progression. Rice-derived bran bioactive peptides (RBAP) might exert antioxidant effect through unknown mechanisms. Herein, we validated the antioxidant effect and mechanism of RBAP on H₂O₂-induced oxidative injury in human umbilical vein endothelial cells (HUVECs). Here, HUVECs were treated with RBAP under H₂O₂ stimulation; the effects of RBAP on HUVECs oxidative injury were evaluated. H₂O₂ injury-induced cell morphology changes were ameliorated by RBAP. The effect of H₂O₂- on HUVEC apoptosis (percentage of apoptotic cell: 38.00 ± 2.00 in H₂O₂ group vs 21.07 ± 2.06 in RBAP + H₂O₂ group, P = 0.0013 compared to H₂O₂ group), the protein levels of cleaved caspase-3 (relative protein expression: 2.90 ± 0.10 in H₂O₂ group vs 1.82 ± 0.09 in RBAP + H₂O₂ group, P < 0.0001 compared to H₂O₂ group) and p-p65 (relative protein expression: 1.86 ± 0.09 in H₂O₂ group vs 1.35 ± 0.08 in RBAP + H₂O₂ group, P < 0.0001 compared to H₂O₂ group) could be attenuated by RBAP. RBAP exerts its protective function through binding with Toll-like receptor 4 (TLR4). Taken together, RBAP protects HUVECs against H₂O₂-induced oxidant injury, which provided the theoretical basis for the molecular mechanism of rice deep processing and exploitation of functional peptides.

Hyperuricemia enhances intracellular urate accumulation via down-regulation of cell-surface BCRP/ABCG2 expression in vascular endothelial cells

Hyperuricemia has been recognized as an independent risk factor for cardiovascular disease. Urate stimulates NADPH oxidase and induces production of reactive oxygen species (ROS); consequently, intracellular urate accumulation can induce oxidative stress leading to endothelial dysfunction. Here, we studied the mechanism involved, using human umbilical vascular endothelial cells (HUVEC) as a model. Pretreatment with 15 mg/dL unlabeled uric acid (corresponding to hyperuricemia) resulted in increased uptake of [¹⁴C]uric acid at steady-state by HUVEC, whereas pretreatment with 5 mg/dL uric acid (in the normal serum concentration range) did not. However, the initial uptake rate of [¹⁴C]uric acid was not affected by uric acid at either concentration. These results suggest that efflux transport of uric acid is decreased under hyperuricemic conditions. We observed a concomitant decrease of phosphorylated endothelial nitric oxide synthase. Plasma membrane expression of breast cancer resistance protein (BCRP), a uric acid efflux transporter, was decreased under hyperuricemia, though the total cellular expression of BCRP remained constant. Uric acid did not affect expression of another uric acid efflux transporter, multidrug resistance associated protein 4 (MRP4). Moreover, phosphorylation of Akt, which regulates plasma membrane localization of BCRP, was decreased. These uric acid-induced changes of BCRP and Akt were reversed in the presence of the antioxidant N-acetylcysteine. These results suggest that in hyperuricemia, uric acid-induced ROS generation inhibits Akt phosphorylation, causing a decrease in plasma membrane localization of BCRP, and the resulting decrease of BCRP-mediated efflux leads to increased uric acid accumulation and dysregulation of endothelial function.

Two-Year Changes in Hyperuricemia and Risk of Diabetes: A Five-Year Prospective Cohort Study

BACKGROUND

Hyperuricemia is known to be a risk factor for diabetes. However, information is limited regarding the association between changes in hyperuricemia and the risk of diabetes.

METHODS

A total of 15,403 participants who were free of diabetes at the time of 2009 and 2011 surveys in the Beijing Health Management Cohort (BHMC) study were recruited and followed up until 2016. Participants were classified into four groups according to 2-year changes in hyperuricemia: no hyperuricemia, remittent hyperuricemia, incident hyperuricemia, and persistent hyperuricemia. Modified Poisson regression models were used to evaluate the effect of 2-year changes in hyperuricemia on the risk of diabetes.

RESULTS

During the 5-year follow-up, we identified 841 new cases of diabetes (216 women). Remittent hyperuricemia and incident hyperuricemia had a 35% and 48% higher risk for developing diabetes compared with no hyperuricemia. Especially, persistent hyperuricemia was associated with a 75% higher risk of diabetes (RR = 1.75, 95% CI = 1.47-2.08). Compared with minor serum uric acid (SUA) change, over 10% decline and over 30% increase in SUA levels were subsequently associated with lower (RR = 0.84, 95% CI = 0.72-0.99) and higher (RR = 1.71, 95% CI = 1.27-2.30) diabetes risk, respectively.

CONCLUSIONS

Changes in hyperuricemia, especially persistent hyperuricemia, are more appropriate to reflect the risk of diabetes than a single measurement of hyperuricemia at baseline. Strategies aiming at preventing hyperuricemia are urgently needed to reduce the increasing burden of diabetes.