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

The potential relationship of coronary artery disease and hyperuricemia: A cardiometabolic risk factor

Coronary arterial disease (CAD) is the leading cause of mortality in the world. Hyperuricemia has recently emerged as a novel independent risk factor of CAD, in addition to the traditional risk factors such as hyperlipidemia, smoking, and obesity. Several clinical studies have shown that hyperuricemia is strongly associated with the risk, progression and poor prognosis of CAD, as well as verifying an association with traditional CAD risk factors. Uric acid or enzymes in the uric acid production pathway are associated with inflammation, oxidative stress, regulation of multiple signaling pathways and the renin-angiotensin-aldosterone system (RAAS), and these pathophysiological alterations are currently the main mechanisms of coronary atherosclerosis formation. The risk of death from CAD can be effectively reduced by the uric acid-lowering therapy, but the interventional treatment of uric acid levels in patients with CAD remains controversial due to the diversity of co-morbidities and the complexity of causative factors. In this review, we analyze the association between hyperuricemia and CAD, elucidate the possible mechanisms by which uric acid induces or exacerbates CAD, and discuss the benefits and drawbacks of uric acid-lowering therapy. This review could provide theoretical references for the prevention and management of hyperuricemia-associated CAD.

Hypertension and cellular senescence

Essential or primary hypertension is a wordwide health problem. Elevated blood pressure (BP) is closely associated not only with increased chronological aging but also with biological aging. There are various common pathways that play a role in cellular aging and BP regulation. These include but not limited to inflammation, oxidative stress, mitochondrial dysfunction, air pollution, decreased klotho activity increased renin angiotensin system activation, gut dysbiosis etc. It has already been shown that some anti-hypertensive drugs have anti-senescent actions and some senolytic drugs have BP lowering effects. In this review, we have summarized the common mechanisms underlying cellular senescence and HT and their relationships. We further reviewed the effect of various antihypertensive medications on cellular senescence and suggest further issues to be studied.

Hyperuricemia exacerbates abdominal aortic aneurysm formation through the URAT1/ERK/MMP-9 signaling pathway

OBJECTIVE

Previous studies have revealed associations between hyperuricemia and microvascular diseases, but the association between hyperuricemia and abdominal aortic aneurysm (AAA) remains unclear. The aim of this study was to elucidate the pathogenesis and prove the relationship between AAA and hyperuricemia.

METHODS

A retrospective study was performed to validate the growth rates of AAA in humans with different serum uric acid levels. A murine model of angiotensin II-induced AAA was used to assess the effects of hyperuricemia on AAA growth in vivo, and human aortic smooth muscle cells (HASMCs) were used to study the pathways involved in these effects in vitro.

RESULTS

We analyzed data from 107 AAA patients and found that patients with serum uric acid levels above 9 mg/dl had higher AAA growth rates than patients with serum uric acid levels between 4 and 7.9 mg/dl. In vivo, induction of hyperuricemia increased the incidence of AAA formation and the abdominal aortic diameter in mice. The hyperuricemic mice exhibited higher levels of urate transporter 1 (URAT1) expression, phospho-extracellular signal-regulated kinase (p-ERK)1/2 expression, reactive oxygen species (ROS) levels and matrix metalloproteinase (MMP)-9 expression in the abdominal aorta than the control mice. Soluble uric acid increased the expression of URAT1, p-ERK1/2, and MMP-9 and the levels of ROS in HASMCs in vitro.

CONCLUSIONS

We have provided human evidence that hyperuricemia exacerbates AAA formation. In addition, our murine experimental evidence suggests that hyperuricemia exacerbates AAA formation and reveals that the URAT1/ERK1/2/ROS/MMP-9 pathway is among the pathways activated by uric acid in HASMCs.

The Role of Antioxidants in the Interplay between Oxidative Stress and Senescence

Cellular senescence is an irreversible state of cell cycle arrest occurring in response to stressful stimuli, such as telomere attrition, DNA damage, reactive oxygen species, and oncogenic proteins. Although beneficial and protective in several physiological processes, an excessive senescent cell burden has been involved in various pathological conditions including aging, tissue dysfunction and chronic diseases. Oxidative stress (OS) can drive senescence due to a loss of balance between pro-oxidant stimuli and antioxidant defences. Therefore, the identification and characterization of antioxidant compounds capable of preventing or counteracting the senescent phenotype is of major interest. However, despite the considerable number of studies, a comprehensive overview of the main antioxidant molecules capable of counteracting OS-induced senescence is still lacking. Here, besides a brief description of the molecular mechanisms implicated in OS-mediated aging, we review and discuss the role of enzymes, mitochondria-targeting compounds, vitamins, carotenoids, organosulfur compounds, nitrogen non-protein molecules, minerals, flavonoids, and non-flavonoids as antioxidant compounds with an anti-aging potential, therefore offering insights into innovative lifespan-extending approaches.

Differences in senescence of late Endothelial Progenitor Cells in non-smokers and smokers

INTRODUCTION

Endothelial Progenitor Cells (EPCs) are part of hematopoietic stem cells that differentiate into endothelial cells during their blood vessels' maturation process. The role of EPCs is widely known to contribute to repair of the vascular wall when endothelial dysfunction occurs. However, various risk factors for cardiovascular disease (CVD) influence EPC performance, leading to endothelial dysfunction. One EPC dysfunction is decreased amount of EPC mobilization to the injured tissue. EPC dysfunction reduces the angiogenetic function of EPCs. The vital maturation process that the EPCs must pass is the late phase. The dysfunction of late EPCs is known as senescence. This study aimed to identify and compare senescence of late EPCs, through CD62E and CD41 markers, in non-smokers and smokers as a risk factor for CVD.

METHODS

EPC collection was from peripheral mononuclear cells (PBMCs) in non-smokers (n=30) and smokers (n=31). The EPCs were then marked by CD62E/CD41 and senescence β-galactosidase assay using FACS. Identification of senescence cells was based on fluorescence with DAPI.

RESULTS

Positive percentage of late EPCs in non-smokers was not significantly different from that in smokers (p=0.014). The number of senescent late EPCs in smokers was higher than in non-smokers (p<0.0001).

CONCLUSIONS

Endothelial progenitor cells that experienced senescence in the smokers showed EPC dysfunction, which resulted in decreased cell angiogenic function. Further research is needed to explain the mechanism of re-endothelialization failure in EPC dysfunction due to smoking.

Vitamin D3 potentiates the nephroprotective effects of metformin in a rat model of metabolic syndrome: role of AMPK/SIRT1 activation and DPP-4 inhibition

The current study aimed to investigate the molecular mechanisms of metformin and vitamin D3-induced nephroprotection in a metabolic syndrome (MetS) rat model, evaluating the capacity of vitamin D3 to potentiate metformin action. MetS was induced by 10% fructose in drinking water and 3% salt in the diet. After 6 weeks, serum lipid profile and uric acid were measured, an oral glucose tolerance test (OGTT) was performed, and kidney function was investigated. In conjunction with the same concentrations of fructose and salt feeding, MetS rats with significant weight gain, dyslipidemia, hyperuricemia, and dysglycemia were treated orally with metformin (200 mg/kg), vitamin D3 (10 µg/kg), or both daily for 6 weeks. At the end of the study period, anthropometrical parameters were recorded, OGTT was reperformed, urine and blood samples were collected, and tissue samples were harvested at sacrifice. MetS rats showed dramatically declined renal function, enhanced intrarenal oxidative stress and inflammation, and extravagant renal histopathological damage with interstitial fibrosis. Metformin and vitamin D3 significantly reversed all the aforementioned deleterious effects in MetS rats. The study has verified the nephroprotective effects of metformin and vitamin D3 in MetS, accentuating the critical role of AMP-activated protein kinase/sirtuin-1 activation and dipeptidyl peptidase-4 inhibition. Given the synergistic effects of the combination, vitamin D3 is worth being investigated as an additional therapeutic agent for preventing MetS-induced nephropathy.

Renoprotective effects of vitamin D3 supplementation in a rat model of metabolic syndrome

PURPOSE

The study aimed to investigate the potential nephroprotective effects of vitamin D3 in metabolic syndrome (MetS) and the molecular basis of the underlying mechanisms of its action.

METHODS

MetS was induced in adult male Wistar rat‏s by adding fructose (10%) to every day drinking water and salt (3%) to the diet. Six weeks after fructose/salt consumption, fasting serum lipid profile and uric acid levels were determined, an oral glucose tolerance test (OGTT) was performed and kidney function was checked. MetS rats were then treated orally with vitamin D3 (10 µg/kg/day) for 6 weeks. At the end of the study period (12 weeks), the OGTT test was reperformed, anthropometrical parameters were measured, urine, blood and tissue samples were collected and the animals were euthanised.

RESULTS

The incidence of MetS was confirmed 6 weeks after fructose/salt consumption, when the rats exhibited significant weight gain, dyslipidemia, hyperuricemia, insulin resistance, hyperinsulinemia and impaired glucose tolerance. After 12 weeks, MetS rats displayed markedly declined renal function alongside with extravagant renal histopathological damages and interstitial fibrosis. Furthermore, significantly enhanced renal oxidative stress and inflammation were manifested. Vitamin D3 supplementation in MetS rats significantly reversed all the above-mentioned deleterious effects.

CONCLUSION

The study has indeed provided mounting evidence of the promising therapeutic potential of vitamin D3 against development and progression of MetS-induced nephropathy. A new insight has been introduced into the crucial role of dipeptidyl peptidase-4 inhibition and sirtuin-1/5'adenosine monophosphate-activated protein kinase activation in the renoprotective effects of vitamin D3.

MeCP2 inhibits cell functionality through FoxO3a and autophagy in endothelial progenitor cells

Objectives: Autophagy is an evolutionarily conserved intracellular degradation mechanism in which cell constituents are phagocytosed to maintain cellular homeostasis. Forkhead box O 3a (FoxO3a) promotes autophagy to protect cells from environmental stress. Methylated CpG binding protein 2 (MeCP2) is a nuclear protein that binds DNA and represses transcription. However, the mechanism and interplay between FoxO3a and MeCP2 underlying endothelial progenitor cell (EPC) function are not fully understood.

Results: In EPCs, MeCP2 overexpression attenuated autophagy and cell functionality, which were reversed by the autophagy activator rapamycin or co-transfection with FoxO3a. FoxO3a promoted cell function, which was reversed by the autophagy inhibitor chloroquine. Following MeCP2 overexpression, MeCP2 was found enriched on the FoxO3a promoter, resulting in promoter hypermethylation and enhanced H3K9 histone modification in nucleosomes of the FoxO3a promoter.

Conclusions: MeCP2 attenuated cell functionality via DNA hypermethylation and histone modification of the FoxO3a promoter to inhibit FoxO3a transcription and autophagy.

Materials and Methods: EPCs were isolated from human umbilical cord blood and treated with adenoviral vectors containing interference sequences. The effects and mechanism of MeCP2 and FoxO3a were analyzed by utilizing western blotting, cell counting kit-8, transwell plates, Matrigel, matrix adhesion, transmission electron microscopy, and chromatin immunoprecipitation.

PJ34, a PARP1 inhibitor, promotes endothelial repair in a rabbit model of high fat diet-induced atherosclerosis

Objective: Atherosclerosis involves endothelial injury caused by oxidative stress. Endothelial progenitor cells (EPCs) play important roles in preventing the early stages of atherosclerosis. Meanwhile, poly (ADP-ribose) polymerase 1 (PARP1) utilizes nicotinamide adenine dinucleotide (NAD⁺) to repair DNA damage. PARP1 overactivation results in excessive NAD⁺ consumption in the presence of pathological DNA damage. PJ34 is a PARP1 inhibitor that attenuates cellular NAD+ depletion and can prevent endothelial dysfunction. However, few studies have been conducted on its effects on EPCs. In this study, we tried to elucidate the action of PJ34 in rabbit EPCs and tested its effectiveness in rabbit atherosclerosis. Methods: We analyzed the effect of PJ34 supplementation by inducing oxidative damage by H₂O₂ in vitro and using a rabbit atherosclerosis model induced by a high-fat-diet in vivo. Transwell, immunofluorescence, Matrigel, and western blot analyses, as well as adenoviral vector transfection were used to quantify the levels of reactive oxygen species, proteins, and NAD⁺. Results: The effects of PJ34 were dependent on SIRT1 levels. In vitro results showed that when oxidative damage attenuated cellular function, PJ34 treatment restored partial functionality. In vivo results confirmed that PJ34 can prevent atherosclerosis in a rabbit model.

PARP1 inhibitor (PJ34) improves the function of aging-induced endothelial progenitor cells by preserving intracellular NAD+ levels and increasing SIRT1 activity

Background

Nicotinamide adenine dinucleotide (NAD⁺) is a critical molecule involved in various biological functions. Poly (ADP-ribose) polymerase 1 (PARP1) and sirtuin 1 (SIRT1) affect cellular NAD⁺ levels and play essential roles in regulating metabolism. However, there has been little research on the effects of PARP1 and SIRT1 crosstalk during senescence.

Methods

We isolated endothelial progenitor cells (EPCs) from human umbilical cord blood and treated them with a PARP1 inhibitor (PJ34).

Results

Using a stress-induced premature aging model built by H₂O₂, transfection with adenoviral vectors, and Western blot analysis, we observed that PJ34 treatment preserved intracellular NAD⁺ levels, increased SIRT1 activity, decreased p53 acetylation, and improved the function of stress-induced premature aging EPCs.

Conclusions

Our results suggest that PJ34 improves the function of aging-induced EPCs and may contribute to cellular therapies for atherosclerosis.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0961-7) contains supplementary material, which is available to authorized users.