Dissociation between urate and blood pressure in mice and in people with early Parkinson's disease

The impact of serum acid, arterial stiffness, and hypertension as a mediating factor: A cohort study

BACKGROUND

Serum uric acid (SUA) has been associated with arterial stiffness. However, previous studies were limited to contradicting cross-sectional studies. This study aimed to examine the longitudinal association between SUA and the progression of arterial stiffness and the potential mechanisms.

METHODS

Based on the Kailuan study, arterial stiffness progression was assessed by the annual growth rate of repeatedly measured brachial-ankle pulse wave velocity (baPWV). Generalized linear regression models were used to estimate the association of SUA with baseline arterial stiffness (n = 37,659) and arterial stiffness progression (n = 16,506), and Cox regressions were used to investigate the risk of incident arterial stiffness (n = 13,843). Mediation analysis was used to explore the potential mediators of the associations.

RESULTS

Per standard deviation increase in SUA was associated with an 11.89 cm/s increment (95% confidence interval [CI], 8.60-15.17) in baseline baPWV and a 2.67 cm/s/yr increment in the annual growth rate of baPWV. During the 5.77-year follow-up, there were 1953 cases of incident arterial stiffness. Participants in the highest quartile of SUA had a 39% higher risk of arterial stiffness (HR, 1.39; 95% CI, 1.21-1.60), as compared with those in the lowest quartile of SUA. Furthermore, the observed associations were more pronounced in women than in men (Pint<0.05). The pathological pathway from high SUA to arterial stiffness was mainly mediated through hypertension (mediated proportion: 24.74%).

CONCLUSIONS

Our study indicates that SUA was positively associated with the risk of arterial stiffness and its progression, especially in women. The association was mainly mediated through hypertension.

Hyperuricaemia and its association with other risk factors for cardiovascular diseases: A population-based study

INTRODUCTION

Cardiovascular diseases are very common in the general population, and several factors play a role in their development. The purpose of this study was to investigate the relationship between hyperuricaemia and other cardiovascular disease risk factors.

METHODS

This cross-sectional study was conducted on 1008 people over the 15-year-old general population in Kerman, Iran. The blood samples of all patients were analysed for the uric acid serum level, and they completed a checklist including physical activity, previous history of hypertension and diabetes, smoking and opium.

RESULTS

A number of 1008 cases of people were entered into the study. According to the results of this study, 254 patients had uric acid levels above the 75th percentile (6 mg/dl in males, and 5 mg/dl in females). No significant difference was observed between gender (p = .249) and age groups (p = .125) of people with and without hyperuricaemia. The prevalence of overweight/obesity (p < .001), hypertension (p = .004) and low physical activity (p = .033) was significantly higher in patients with hyperuricaemia. The duration of hypertension was significantly higher in hyperuricaemic individuals (p = .022). Overweight/obesity (OR = 2.67; 95% CI = 1.87-3.82) and hypertension (OR = 1.40; 95% CI = 1.02-1.93) were two significant independent factors that contributed to the increased risk of hyperuricaemia in the subjects.

CONCLUSION

The uric acid serum level is higher in people with hypertension and overweight/obesity. Hyperuricaemia increases the risk of cardiovascular events, which can be prevented by determining the appropriate strategy for the early diagnosis and treatment of this metabolic disorder.

Inosine in Neurodegenerative Diseases: From the Bench to the Bedside

Neurodegenerative diseases, such as Alzheimer′s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), currently represent major unmet medical needs. Therefore, novel therapeutic strategies are needed in order to improve patients’ quality of life and prognosis. Since oxidative stress can be strongly involved in neurodegenerative diseases, the potential use of inosine, known for its antioxidant properties, in this context deserves particular attention. The protective action of inosine treatment could be mediated by its metabolite urate. Here, we review the current preclinical and clinical studies investigating the use of inosine in AD, PD, ALS, and MS. The most important properties of inosine seem to be its antioxidant action and its ability to raise urate levels and to increase energetic resources by improving ATP availability. Inosine appears to be generally safe and well tolerated; however, the possible formation of kidney stones should be monitored, and data on its effectiveness should be further explored since, so far, they have been controversial. Overall, inosine could be a promising potential strategy in the management of neurodegenerative diseases, and additional studies are needed in order to further investigate its safety and efficacy and its use as a complementary therapy along with other approved drugs.

Neuroglial Senescence, α-Synucleinopathy, and the Therapeutic Potential of Senolytics in Parkinson’s Disease

Parkinson’s disease (PD) is the most common movement disorder and the second most prevalent neurodegenerative disease after Alzheimer’s disease. Despite decades of research, there is still no cure for PD and the complicated intricacies of the pathology are still being worked out. Much of the research on PD has focused on neurons, since the disease is characterized by neurodegeneration. However, neuroglia has become recognized as key players in the health and disease of the central nervous system. This review provides a current perspective on the interactive roles that α-synuclein and neuroglial senescence have in PD. The self-amplifying and cyclical nature of oxidative stress, neuroinflammation, α-synucleinopathy, neuroglial senescence, neuroglial chronic activation and neurodegeneration will be discussed. Finally, the compelling role that senolytics could play as a therapeutic avenue for PD is explored and encouraged.

Inosine as a Tool to Understand and Treat Central Nervous System Disorders: A Neglected Actor?

Since the 1970s, when ATP was identified as a co-transmitter in sympathetic and parasympathetic nerves, it and its active metabolite adenosine have been considered relevant signaling molecules in biological and pathological processes in the central nervous system (CNS). Meanwhile, inosine, a naturally occurring purine nucleoside formed by adenosine breakdown, was considered an inert adenosine metabolite and remained a neglected actor on the purinergic signaling scene in the CNS. However, this scenario began to change in the 1980s. In the last four decades, an extensive group of shreds of evidence has supported the importance of mediated effects by inosine in the CNS. Also, inosine was identified as a natural trigger of adenosine receptors. This evidence has shed light on the therapeutic potential of inosine on disease processes involved in neurological and psychiatric disorders. Here, we highlight the clinical and preclinical studies investigating the involvement of inosine in chronic pain, schizophrenia, epilepsy, depression, anxiety, and in neural regeneration and neurodegenerative diseases, such as Parkinson and Alzheimer. Thus, we hope that this review will strengthen the knowledge and stimulate more studies about the effects promoted by inosine in neurological and psychiatric disorders.

Uric Acid and Cardiovascular Disease: An Update From Molecular Mechanism to Clinical Perspective

Uric acid (UA) is the end product of purine nucleotide metabolism in the human body. Hyperuricemia is an abnormally high level of UA in the blood and may result in arthritis and gout. The prevalence of hyperuricemia has been increasing globally. Epidemiological studies have shown that UA levels are positively correlated with cardiovascular diseases, including hypertension, atherosclerosis, atrial fibrillation (AF), and heart failure (HF). Hyperuricemia promotes the occurrence and development of cardiovascular diseases by regulating molecular signals, such as inflammatory response, oxidative stress, insulin resistance/diabetes, endoplasmic reticulum stress, and endothelial dysfunction. Despite extensive research, the underlying molecular mechanisms are still unclear. Allopurinol, a xanthine oxidase (XO) inhibitor, has been shown to improve cardiovascular outcomes in patients with HF, coronary heart disease (CHD), type 2 diabetes (T2D), and left ventricular hypertrophy (LVH). Whether febuxostat, another XO inhibitor, can improve cardiovascular outcomes as well as allopurinol remains controversial. Furthermore, it is also not clear whether UA-lowering treatment (ULT) can benefit patients with asymptomatic hyperuricemia. In this review, we focus on the latest cellular and molecular findings of cardiovascular disease associated with hyperuricemia and clinical data about the efficacy of ULT in patients with cardiovascular disease.

Purine Metabolite Signatures and Type 2 Diabetes: Innocent Bystanders or Actionable Items?

PURPOSE OF REVIEW

This article reviews evidence linking cardiometabolic conditions with changes in purine metabolites, including increased serum uric acid (sUA), and discusses intervention studies that investigated the therapeutic relevance of these associations.

RECENT FINDINGS

Metabolic and epidemiological findings support a correlation between sUA and circulating levels of other purines with insulin resistance (IR) and risk factors for cardiovascular disease (CVD). In addition, increased activity of xanthine oxidoreductase (XOR), the rate-limiting enzyme for UA production, has been detected in tissues targeted by obesity. Yet, inhibition of XOR in pre-clinical and clinical studies generally failed to support a causal role for excess sUA in IR and CVD. The lack of efficacy of XOR inhibitors strongly suggests that UA is a marker of, rather than a direct contributory factor for, cardiometabolic diseases. Validation of the function of other purines will require a paradigm shift, from a "UA-centric" view to a more granular assessment of the entire purine network and its interaction with other pathways.