Mesoporous tantalum oxide nanomaterials induced cardiovascular endothelial cell apoptosis via mitochondrial-endoplasmic reticulum stress apoptotic pathway

Along with its wide range of potential applications, human exposure to mesoporous tantalum oxide nanomaterials (PEG@mTa₂O₅) has substantially risen. Accumulative toxic investigations have shown the PEG@mTa₂O₅ intake and cardiovascular diseases (CVD). Endothelial cell death is crucial in the onset and development of atherosclerosis. Still, the molecular mechanism connecting PEG@mTa₂O₅ and endothelium apoptosis remains unclear. Herein, we studied the absorption and toxic action of mesoporous tantalum oxide (mTa₂O₅) nanomaterials with polyethylene glycol (PEG) utilizing human cardio microvascular endothelial cells (HCMECs). We also showed that PEG@mTa₂O₅ promoted apoptosis in endothelial cells using flow cytometry and AO-EB staining. In conjunction with the ultrastructure modifications, PEG@mTa₂O₅ prompted mitochondrial ROS production, cytosolic Ca²⁺ overload, ΔΨm collapse, and ER stress verified by elevated ER-Tracker staining, upregulated XBP1 and GRP78/BiP splicing. Remarkably, the systemic toxicity and blood compatibility profile of PEG@mTa₂O₅ can greatly improve successive therapeutic outcomes of NMs while reducing their adverse side effects. Overall, our findings suggested that PEG@mTa₂O₅-induced endothelium apoptosis was partially mediated by the activation of the endoplasmic reticulum stress-mitochondrial cascade.

miR-221-3p targets Ang-2 to inhibit the transformation of HCMECs to tip cells

Postembryonic angiogenesis is mainly induced by various proangiogenic factors derived from the original vascular network. Previous studies have shown that the role of Ang-2 in angiogenesis is controversial. Tip cells play a vanguard role in angiogenesis and exhibit a transdifferentiated phenotype under the action of angiogenic factors. However, whether Ang-2 promotes the transformation of endothelial cells to tip cells remains unknown. Our study found that miR-221-3p was highly expressed in HCMECs cultured for 4 h under hypoxic conditions (1% O2 ). Moreover, miR-221-3p overexpression inhibited HCMECs proliferation and tube formation, which may play an important role in hypoxia-induced angiogenesis. By target gene prediction, we further demonstrated that Ang-2 was a downstream target of miR-221-3p and miR-221-3p overexpression inhibited Ang-2 expression in HCMECs under hypoxic conditions. Subsequently, qRT-PCR and western blotting methods were performed to analyse the role of miR-221-3p and Ang-2 on the regulation of tip cell marker genes. MiR-221-3p overexpression inhibited CD34, IGF1R, IGF-2 and VEGFR2 proteins expression while Ang-2 overexpression induced CD34, IGF1R, IGF-2 and VEGFR2 expression in HCMECs under hypoxic conditions. In addition, we further confirmed that Ang-2 played a dominant role in miR-221-3p inhibitors promoting the transformation of HCMECs to tip cells by using Ang-2 shRNA to interfere with miR-221-3p inhibitor-treated HCMECs under hypoxic conditions. Finally, we found that miR-221-3p expression was significantly elevated in both serum and myocardial tissue of AMI rats. Hence, our data showed that miR-221-3p may inhibit angiogenesis after acute myocardial infarction by targeting Ang-2 to inhibit the transformation of HCMECs to tip cells.

Vaspin contributes to autophagy and endothelial-to-mesenchymal transition via PI3K-/AKT-mTOR pathway

BACKGROUND

Visceral adipose tissue-derived serine protease inhibitor (Vaspin) was found to have anti-inflammatory, anti-apoptosis, and pro-autophagy activities. Our investigation is aimed to ascertain the effect of Vaspin on hypoxia-evoked endothelial-mesenchymal transition (EndMT) in human cardiac microvascular endothelial cells (HCMECs).

METHODS

In vitro assays including CCK8, TUNEL, western blots, RT-qPCR to assess the effect of Vaspin on hypoxia-induced cell injuries, endothelial-mesenchymal transition (EndMT) and the inflammatory state in HCMECs. Transmission electron microscopy (TEM) was used to monitor autophagosome formation in HCMECs. The autophagy related proteins coupled with the critical effectors of PI3K/AKT-mTOR signaling pathway were also detected by western blots. In vivo assays including HE and ELISA to assess the effects of Vaspin on myocardial fibrosis pathology and type I and type III collagen in rats.

RESULTS

Vaspin pretreatment dramatically dose-dependently restored the proliferative impairment and the induced EndMT in HCMECs by hypoxia. The Vaspin-pretreated HCMECs also presented with attenuated expression of increased IL-1β, TNF-α and IL-6 by hypoxia a dose-dependent manner. Vaspin alleviated rat MF. The impact of Vaspin is also related to the increased autophagy and activated PI3K/AKT-mTOR signaling pathway. The protective and pro-autophagy activity of Vaspin was antagonized by the PI3K/AKT-mTOR inhibitor LY294002.

CONCLUSION

Vaspin ameliorated the hypoxia-stimulated cell injuries and EndMT by activating autophagy via PI3K/AKT-mTOR signaling pathway.