Oxidative stress and valvular endothelial cells in aortic valve calcification

Calcified aortic valve disease (CAVD) is a common cardiovascular disease in elderly individuals. Although it was previously considered a degenerative disease, it is, in fact, a progressive disease involving multiple mechanisms. Aortic valve endothelial cells, which cover the outermost layer of the aortic valve and are directly exposed to various pathogenic factors, play a significant role in the onset and progression of CAVD. Hemodynamic changes can directly damage the structure and function of valvular endothelial cells (VECs). This leads to inflammatory infiltration and oxidative stress, which promote the progression of CAVD. VECs can regulate the pathological differentiation of valvular interstitial cells (VICs) through NO and thus affect the process of CAVD. Under the influence of pathological factors, VECs can also be transformed into VICs through EndMT, and then the pathological differentiation of VICs eventually leads to the formation of calcification. This review discusses the role of VECs, especially the role of oxidative stress in VECs, in the process of aortic valve calcification.

Inhibition of miR-122 reduced atherosclerotic lesion formation by regulating NPAS3-mediated endothelial to mesenchymal transition

AIMS

Endothelial to mesenchymal transition (EndMT) is closely related to atherosclerosis. Herein, we aim to determine whether miR-122 is involved in EndMT and the underlying mechanism in atherosclerosis.

MAIN METHODS

qRT-PCR was performed to detect miR-122 expression in ApoE^-/- mice and cellular EndMT model induced by H₂O₂. MiR-122 expression in vivo was modulated by lenti-virus injection and by genetic manipulation. Hematoxylin and eosin (HE) and Oil-red O staining were used to observe the plaque size and lipid accumulation in the aortic roots. F4/80 staining, elastin staining, and masson staining were used to observe the components of atherosclerotic lesions. MiR-122 expression in endothelial cells was modulated by transfection of miR-122 mimic and inhibitor. Western blotting and co-localization of endothelial markers (VE-cadherin, CD31) and mesenchymal markers (Vimentin, α-SMA) were carried out to determine EndMT.

KEY FINDINGS

MiR-122 was upregulated in the aortic intima and serum of ApoE^-/- mice induced by HFD and in cellular EndMT model. Inhibition of miR-122 repressed the atherosclerotic plaque progression and vulnerable plaque formation in ApoE^-/- mice. In vitro, endothelial cells acquired a spindle-shaped morphology accompanying decrease of the endothelial markers (VE-cadherin, CD31) and increase of the mesenchymal markers (Vimentin, α-SMA) in the presence of H₂O₂, which was inhibited by miR-122 inhibitor. Furthermore, NPAS3 functions as a target of miR-122, and NPAS3 silencing abolished the anti-EndMT effect of miR-122 inhibitor.

SIGNIFICANCE

Inhibition of miR-122 prevents atherosclerosis and regulates NPAS3-mediated EndMT, suggesting that miR-122 may be a novel target in the treatment of EndMT-associated diseases including atherosclerosis.

Lactic acid-mediated endothelial to mesenchymal transition through TGF-β1 contributes to in-stent stenosis in poly-L-lactic acid stent

Currently, bioresorbable stents made with biodegradable materials are attracting more and more attentions in cardiovascular tissue engineering. Especially, poly-L-lactic acid (PLLA) stent has been regarded as the most promising one due to excellent biodegradability until serious in-stent restenosis at late stage was reported. This imply that the PLLA stent has side effect in cell function, and it is rarely reported the effect of degradation product of PLLA on endothelial function. Here we reported that lactic acid (LA) not acidic pH induced endothelial-to-mesenchymal transition (EndMT) leading to vascular fibrosis which may contribute to in-stent stenosis after PLLA stent implantation. Furthermore, we found TGF-β1 signaling was involved in boosting EndMT by LA. These results demonstrate a mechanism of in-stent stenosis induced by PLLA and indicate its utility for the future design of polymeric vascular scaffolds.