Effect of silver nanoparticles (AgNPs) exposure on microRNA expression and global DNA methylation in endothelial cells EA.hy926.

The aim of this study was to determine the effect of AgNPs on the epigenome of endothelial cells EA.hy926, including the levels of expression of microRNAs (miRNAs) and global DNA methylation patterns. In addition, evaluation of the expression of inflammatory genes and the levels of VCAM-1 protein (miRNA-126 target) was performed. The expression levels of analyzed miRNAs (microRNAs-126, 155 and 146) were reduced significantly and there were not observed changes in inflammatory gene expression. Regarding the levels of protein vascular cell adhesion molecule 1 (VCAM-1), they increase significantly to 0.5 µM AgNPs at 24 h of exposure. As far as DNA methylation is concerned, we found that AgNPs induce a state of global hyper-methylation. In conclusion, it was demonstrated that direct contact between AgNPs and endothelial cells resulted in the dysregulation of highly enriched and vastly functional miRNAs and DNA hypermethylation, that may have multiple effects on endothelium function and integrity.

The inflammatory state of adipose tissue is not affected by the anti-inflammatory response of the A2a-adenosine system and miR-221/PTEN.

Obesity is a chronic inflammatory state with cytokines, adipokines, and miRNAs. The A2a-adenosine system decreases activation and cytokine release in immune cells. MiR-221 is upregulated in carcinogenesis and inflammatory processes, where its targets PTEN and ETS-1, negatively regulates the Akt pathway and induces the release of pro-inflammatory cytokines, respectively. However, the roles of the A2a-adenosine system and miR-221 in adipose tissue are unknown. The aim of this work was to evaluate the A2a-adenosine and miRNA pathways as immune modulators in adipose tissue. We collected aspirate of adipose tissue from patients with BMI < 25 kg/m2 (BMI < 25) and BMI ≥ 25 kg/m2 (BMI ≥ 25) who underwent liposuction; the adipose tissue was digested with collagenase, and then a Ficoll gradient was performed to obtain mononuclear cells from adipose tissue (MCAT). We evaluated the A2a levels by quantitative Retro-transcriptase Polymerase Chain Reaction (RT-qPCR) and flow cytometry and the A2a-adenosine function with a proliferation assay or cytokine levels in the presence or absence of NAD+, activators, and inhibitors of the system. We also analyzed miR-221, ETS-1 and PTEN levels by qRT-PCR. First, we detected that MCAT presented higher basal proliferation than mononuclear cells from peripheral blood; however, activation of the A2a receptor downregulated cell proliferation and cytokine release. Interestingly, while miR-221 was downregulated in MCAT from subjects with BMI ≥ 25 compared to BMI < 25, their targets ETS-1 and PTEN, were increased. In conclusion, the A2a-adenosine system is decreased in MCAT, but it maintains its function; moreover, miR-221 could participate in promoting inflammation in adipose tissue.