Endothelial dysfunction and body mass index: is there a role for plasma peroxynitrite?

Fine particulate matter and intima media thickness: Role of endothelial function biomarkers

Background

Ambient fine particulate matter (PM2.5) is a risk factor for atherosclerosis disease. We aimed to assess whether nitric oxide stable metabolites (NOx) and l-arginine mediate the association between PM2.5 and carotid intima media thickness (cIMT) increase.

Methods

We selected 251 participants from the control group of GEA (Genetics of Atheroslerosis Disease Mexican) study (2008-2013) in Mexico City. Mediation models were carried out using pathway analyses, a special case of structural equation models.

Results

The median concentration of PM2.5 area under the curve (auc) was 25.2 µg/m3 (interquartile range: 24.2-26.4 µg/m3). Employing participants with observed values for both biomarkers (n = 117), the total effect of PM2.5auc on mean cIMT at bilateral, right, and left was 19.27 µm (95% confidence interval [CI]: 5.77, 32.78; P value = 0.005), 12.69 µm (95% CI: 0.67, 24.71; P value = 0.039), and 25.86 µm (95% CI: 3.18, 48.53; P value = 0.025) per each 1 µg/m3 increase of PM2.5auc. The direct effect of PM2.5auc (per 1 µg/m3 increase) was 18.89 µm (95% CI: 5.37, 32.41; P value = 0.006) for bilateral, 13.65 µm (95% CI: 0.76, 26.55; P value = 0.038) for right, and 24.13 µm (95% CI: 3.22, 45.03; P value = 0.024) for left. The indirect effects of NOx and l-arginine were not statistically significant showing that endothelial function biomarkers did not mediate PM2.5 and cIMT associations. Although l-arginine was not a mediator in the PM2.5 and cIMT pathway, a decrease in l-arginine was significantly associated with PM2.5auc.

Conclusions

In this study of adults from Mexico City, we found that PM2.5 was associated with an increase in cIMT at bilateral, left, and right, and these associations were not mediated by endothelial function biomarkers (l-arginine and NOx).

Butylated hydroxyanisole induces vascular endothelial injury via TFEB-mediated degradation of GPX4 and FTH1

Butylated hydroxyanisole (BHA) is one of the most commonly used antioxidants and is widely used in food, but whether it causes vascular damage has not been clearly studied. The present study demonstrated for the first time that BHA reduced the viability of human umbilical vein endothelial cells (HUVECs) and mouse brain microvascular endothelial cells (BEND3) in a dose- and time-dependent manner. Moreover, BHA inhibited the migration and proliferation of vascular endothelial cells (ECs). Further analysis revealed that in ECs, the ferroptosis inhibitor ferrostatin-1 (Fer-1) reversed the BHA-induced increase in Fe2+ and malonaldehyde (MDA) levels. Acridine orange staining demonstrated that BHA increased lysosomal permeability. At the protein level, BHA increased the expression of transcription factor EB (TFEB) and decreased the expression of glutathione peroxidase (GPX4), solute carrier family 7 member 11 (SLC7A11, xCT), and ferritin heavy chain 1 (FTH1). Moreover, these effects of BHA could be reversed by knocking down TFEB. In vivo experiments confirmed that BHA caused elevated pulse wave velocity (PWV) and reduced acetylcholine-dependent vascular endothelial diastole. In conclusion, BHA degrades GPX4, xCT, and FTH1 through activation of the TFEB-mediated lysosomal pathway and promotes ferroptosis, ultimately leading to vascular endothelial cell injury.

Time-Restricted Feeding Improved Vascular Endothelial Function in a High-Fat Diet-Induced Obesity Rat Model

Obesity, where there is enhancement of stored body fat in adipose tissues, is associated with cardiovascular complications that are mainly related to atherosclerosis. Time-restricted feeding (TRF) is a form of restricted eating aimed at reducing weight in obese subjects. The present study aims to investigate changes in vascular endothelial function, endothelial nitric oxide synthase (eNOS), and protein kinase B (Akt) protein expressions with TRF in obese and normal rats. Male Sprague Dawley rats were divided into two normal and three obese groups; obesity was induced in the obese groups by feeding with a high-fat diet (HFD) for six weeks. After six weeks, rats were equally divided into five groups (n = 7 per group): Normal group (NR) which continued on a standard diet for six more weeks, normal group switched to TRF with a standard diet for six weeks (NR + TRFSD), obese group (OR) which continued on HFD for six more weeks, obese group switched to TRF of HFD (OR + TRFHFD), and obese group switched to TRF of a standard diet (OR + TRFSD). TRF was practiced for six weeks, after which the rats were sacrificed. Aortic endothelium-dependent and endothelium-independent relaxations and contractions were assessed using the organ bath. Aortic eNOS and Akt protein expressions were determined using immunoblotting. Fasting blood glucose, body weight, body mass index (BMI), serum lipid profile, Lee’s index, serum insulin levels, and sensitivity (HOMA-IR) were also measured. Endothelium-dependent relaxation was significantly impaired, while endothelium-dependent contraction increased in obese rats compared to that in normal rats. Both obese groups which underwent TRF with a HFD and standard diet improved their impairments in endothelium-dependent relaxation and reduced endothelium-dependent contraction; these were associated with increased expressions of aortic eNOS and Akt protein. Both obese groups with TRF reduced body weight, BMI, Lee’s index, total cholesterol, triglycerides, low-density lipoprotein cholesterol, and improved insulin sensitivity. TRF improved endothelium-dependent relaxation and reduced endothelium-dependent contraction, thus attenuating endothelial dysfunction in obese rats. These were associated with increased aortic eNOS and Akt protein expressions.