Downregulated GTCPH I/BH4 Pathway and Decreased Function of Circulating Endothelial Progenitor Cells and Their Relationship with Endothelial Dysfunction in Overweight Postmenopausal Women

Flow-Mediated Dilatation in the Assessment of Coronary Heart Disease: A Meta-Analysis

Endothelial dysfunction may contribute to the increased morbidity and mortality associated with coronary heart disease (CHD). Flow-mediated dilatation (FMD) is the most popular noninvasive method for vascular endothelial function evaluation. This meta-analysis aimed to investigate the association between FMD and CHD. We searched the publications listed in the PubMed, Web of Science, Scopus, and Embase databases. Stata 14 software was used to analyze the data. Standardized mean difference (SMD) was used to calculate FMD levels, and the effect sizes were expressed with a 95% confidence interval (CI). I² statistics were used to evaluate statistical heterogeneity. In this meta-analysis, 9 studies enrolled a total number of 943 participants, including 534 (56.63%) patients with CHD and 409 controls (43.37%). We found that patients with CHD showed a significantly lower FMD than the controls (SMD −0.706%; 95% CI: −0.985, −0.427; P=0.001) with high heterogeneity. In addition, funnel plot analysis suggested asymmetry that could be evidence of publication bias. But sensitivity analyses show that there were no influential studies. This meta-analysis provides evidence that patients with CHD show a significantly lower FMD than controls and highlights the literature on FMD as a hallmark in CHD diseases.

Relationship of the Circulating Endothelial Progenitor Cells to the Severity of a Coronary Artery Lesion in Unstable Angina

The number and function of circulating endothelial progenitor cells (EPCs) decreased in stable coronary artery disease. Nevertheless, there were few studies that explored the variation of EPC and the relationship with the severity of coronary artery lesions in unstable angina (UA). Therefore, this leaves an area for the investigation of the difference in the number and activity of circulating EPCs and the relationship with the Gensini score in unstable angina. Fluorescence-activated cell sorter analysis, as well as DiI-acLDL and lectin fluorescent staining measure the number of circulating EPCs. The transwell chamber assay and MTT were evaluated by the migration and proliferation of circulating EPCs. In addition, the flow-mediated dilation (FMD), Gensini score, and IL-6 levels in plasma were determined. We found that UA patients had the higher number and lower function of circulating EPCs. With the increase in severity of coronary artery lesions, the migration and proliferation of EPCs were decreased. Moreover, the function of the circulating EPCs was negatively associated with severity of coronary artery lesions in unstable angina. In addition, UA patients presented elevated IL-6, which was negatively correlated with the function of circulating EPCs and FMD and positively correlated with the severity of coronary artery lesions evaluated by the Gensini score. These findings revealed the decline in the function of circulating EPCs was associated with the severity of coronary artery disease, which may be related to systemic inflammation.

Endothelial colony forming cells' tetrahydrobiopterin level in coronary artery disease patients and its association with circulating endothelial progenitor cells

Endothelial colony forming cells (ECFCs) participate in neovascularization. Endothelial nitric oxide synthase (eNOS) derived NO· helps in homing of endothelial progenitor cells (EPCs) at the site of vascular injury. The enzyme cofactor tetrahydrobiopterin (BH4) stabilizes the catalytic active state of eNOS. Association of intracellular ECFCs biopterins and ratio of reduced to oxidized biopterin (BH4:BH2) with circulatory EPCs and ECFCs functionality have not been studied. We investigated ECFCs biopterin levels and its association with circulatory EPCs as well as ECFCs proliferative potential in terms of day of appearance in culture. Circulatory EPCs were enumerated by flowcytometry in 53 coronary artery disease (CAD) patients and 42 controls. ECFCs were cultured, characterized, and biopterin levels assessed by high performance liquid chromatography. Appearance of ECFCs' colony and their number were recorded. Circulatory EPCs were significantly lower in CAD and ECFCs appeared in 56% and 33% of CAD and control subjects, respectively. Intracellular BH4 and BH4:BH2 were significantly reduced in CAD. BH4:BH2 was positively correlated with circulatory EPCs (p = 0.01), and negatively with day of appearance of ECFCs (p = 0.04). Circulatory EPCs negatively correlated with ECFCs appearance (p = 0.02). These findings suggest the role of biopterins in maintaining circulatory EPCs and functional integrity of ECFCs.

Vitamin D (1,25-(OH)2D3) Improves Endothelial Progenitor Cells Function via Enhanced NO Secretion in Systemic Lupus Erythematosus

It has been proven that vitamin D was decreased and function of circulating endothelial progenitor cells (EPCs) was injured in systemic lupus erythematosus (SLE) patients. However, the effect of vitamin D on the function of EPCs in vitro and its mechanism need further study. Therefore, we investigated whether vitamin D improved the function of EPCs in vitro. The peripheral blood mononuclear cells of the participants were isolated from SLE patients and control subjects and cultured to EPCs. After the EPCs were treated with vitamin D (1,25-(OH)₂D₃), we evaluated the number, migratory and proliferative activities, and nitric oxide (NO) production of EPCs in vitro and detected vascular endothelial function by flow-mediated dilatation (FMD). We found that vitamin D in a dose-dependent manner improved number and migratory and proliferative activities of EPCs from SLE patients. Additionally, vitamin D upregulated NO production from EPCs in vitro. A significant correlation between the FMD and plasma NO level was found. There was also a correlation between number, migration, and proliferation of EPCs and NO production. Thus, the present findings indicated that vitamin D improved the function of EPCs from SLE patients via NO secretion.

Rejuvenated Circulating Endothelial Progenitor Cells and Nitric Oxide in Premenopausal Women with Hyperhomocysteinemia

Hyperhomocysteinemia (HHcy) induced endothelial dysfunction is associated with disturbance in circulating endothelial progenitor cells (EPCs). Nevertheless, whether this unfavorable effect of HHcy on circulating EPCs also exists in premenopausal women is still unknown. Therefore, this leaves an area for the investigation of the difference on the number and activity of circulating EPCs in premenopausal women with hyperhomocysteinemia and its underlying mechanism. The number of circulating EPCs was measured by fluorescence-activated cell sorter analysis, as well as DiI-acLDL and lectin fluorescent staining. The migration and proliferation of circulating were evaluated by the Transwell chamber assay and MTT. Additionally, the endothelial function and levels of nitric oxide (NO), VEGF, and GM-CSF in plasma and culture medium were determined. The number or activity of circulating EPCs and flow-mediated dilatation (FMD) in premenopausal women with or without HHcy were higher than those in postmenopausal women. However, no significant effect of HHcy on the number or activity of circulating EPCs in premenopausal women was observed. A similar alteration in NO level between the four groups was observed. There was a correlation between FMD and the number or activity of EPCs, as well as NO level in plasma or secretion by EPCs. For the first time, our findings illuminated the quantitive or qualitative alterations of circulating EPCs and endothelial function in premenopausal patients with HHcy are preserved, which was associated with retained NO production. The recuperated endothelial repair capacity is possibly the potential mechanism interpreting cardiovascular protection in premenopausal women with HHcy.

Fasting Therapy Contributes to the Improvement of Endothelial Function and Decline in Vascular Injury-Related Markers in Overweight and Obese Individuals via Activating Autophagy of Endothelial Progenitor Cells

Background

High body mass index- (BMI-) related vascular injury contributes to the pathogenesis of the atherosclerotic cardiovascular disease (ASCVD). Rigorous calorie restriction is one of the major lifestyle interventions to reduce vascular risk in overweight or obese individuals. However, the effects of fasting therapy (FT) on vascular function and the mechanism are still unclear. This study was aimed to investigate the impacts of FT on endothelial function, arterial stiffness, and circulating arterial damage parameters in overweight and obese individuals and possible mechanism.

Methods

Overweight and obese individuals participated in FT intervention (7-day very low calorie diet). Arterial function including brachial arterial flow-mediated dilation (FMD), brachial-ankle pulse wave velocity (baPWV), vascular injury-related markers including trimethylamine N-oxide (TMAO), and leptin and endothelial microparticles (EMPs) were assessed. Endothelial progenitor cells (EPCs) of these participants were isolated and cultured to investigate EPCs function. mRFP-GFP-LC3 confocal microscopy scanning and western blot were carried out to determine autophagy.

Results

After FT, body weight and BMI significantly decreased (81.76 ± 12.04 vs. 77.51 ± 12.06 kg, P < 0.01; 29.93 ± 2.82 vs. 28.47 ± 2.83 kg/m², P < 0.01). FT remarkably improved FMD (5.26 ± 1.34 vs. 6.25 ± 1.60%, P=0.01) while baPWV kept unchanged. TMAO and leptin levels decreased (3.96 ± 1.85 vs. 2.73 ± 1.33 μmol/L, P=0.044; 6814 ± 2639 vs. 3563 ± 2668 μmol/L, P < 0.01). EMPs showed a decreased tendency. EPCs function was significantly improved, autophagy fluorescence intensity was enhanced, and the level of Beclin1, Atg5, LC3 II/I also increased after starvation in vitro, and the effects were blocked by autophagy inhibitor.

Conclusions

Our present study demonstrated for the first time that FT markedly improves endothelial function and reduces the levels of arterial injury markers through improving EPCs function via activating autophagy. These findings provide a novel insight into FT as a lifestyle intervention strategy to promote the maintenance of vascular homeostasis in overweight or obese individuals. The trial was registered with ChiCTR1900024290.

Reduced Circulating Endothelial Progenitor Cells and Downregulated GTCPH I Pathway Related to Endothelial Dysfunction in Premenopausal Women with Isolated Impaired Glucose Tolerance

Background

Individuals at a prediabetic stage have had an augmented cardiovascular disease (CVD) risk and CVD-related mortality compared to normal glucose tolerance (NGT) individuals, which may be attributed to the impaired vascular endothelial repair capacity. In this study, circulating endothelial progenitor cells' (EPCs) number and activity were evaluated, and the underlying mechanisms in premenopausal women with impaired glucose regulation were explored.

Methods

Circulating EPCs' number and activity and flow-mediated dilation (FMD) were compared in premenopausal women with NGT, isolated impaired fasting glucose (i-IFG), or isolated impaired glucose tolerance (i-IGT). Plasma nitric oxide (NO), EPCs-secreted NO, and intracellular BH4 levels were also measured. The key proteins (Tie2, Akt, eNOS, and GTPCH I) in the guanosine triphosphate cyclohydrolase/tetrahydrobiopterin (GTPCH/BH4) pathway and Tie2/Akt/eNOS signaling pathway were evaluated in these women.

Results

It was observed that the i-IGT premenopausal women not i-IFG premenopausal women had a significant reduction in circulating EPCs' number and activity as well as reduced FMD when compared to NGT subjects. Plasma NO levels or EPCs-secreted NO also decreased only in i-IGT women. The expression of GTCPH I as well as intracellular BH4 levels declined in i-IGT women; however, the alternations of key proteins' expression in the Tie2/Akt/eNOS signaling pathway were not observed in either i-IGT or i-IFG women.

Conclusions

The endothelial repair capacity was impaired in i-IGT premenopausal women but was preserved in i-IFG counterparts. The underlying mechanism may be associated with the downregulated GTCPH I pathway and reduced NO productions.

Elevated GTP Cyclohydrolase I Pathway in Endothelial Progenitor Cells of Overweight Premenopausal Women

Background/Aims. Sexual differences exist in endothelial progenitor cells (EPCs), and various cardiovascular risk factors are associated with the preservation of endothelial function in premenopausal women. However, it is unclear whether differences in endothelial function and circulating EPCs exist between overweight premenopausal women and age-matched men. Methods. We compared EPC counting and functions in normal-weight and overweight premenopausal women and men, evaluated endothelial function in each group, and detected the expression of the guanosine triphosphate cyclohydrolase I (GTPCH I) pathway. Results. The number of EPCs was lower in the male group than in the female group, regardless of normal-weight or overweight status, and there was no significant difference between the different weight groups among females or males. Endothelial function and EPC migration and proliferation were preserved in overweight premenopausal women compared with overweight men as were nitric oxide (NO) levels in plasma and secreted by EPCs. Endothelial function, the circulating EPC population, and NO levels were not different between normal-weight and overweight premenopausal women. Flow-mediated dilatation was significantly correlated with EPC function, plasma NO levels, and EPC-secreted NO. Conclusions. This investigation provides the first evidence for sex-based differences in EPC activity and endothelial function in overweight middle-aged individuals; these differences are associated with alterations in NO production and may partly occur through downregulation of the GTPCH I pathway. The present results provide new insights into the mechanism underlying the preserved endothelial function in overweight premenopausal women and may uncover a potential therapeutic target for endothelial repair in overweight population.