Angiotensin-converting enzyme inhibitors provide a protective effect on hypoxia-induced injury in human coronary artery endothelial cells via Nrf2 signaling and PLVAP

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEIs) were reported to protect from hypoxia-induced oxidative stress in coronary endothelial cells (CECs) after acute myocardial infarction (AMI). Nrf2 shows a protective effect in hypoxia-induced CECs after AMI. Plasmalemma vesicle-associated protein (PLVAP) plays a pivotal role in angiogenesis after AMI.

AIM

To explore the protective effect of ACEIs and the involved mechanisms under hypoxia challenge.

METHODS

Human coronary endothelial cells (HCAECs) were used to establish hypoxia-induced oxidative stress injury in vitro. Flow cytometry was used to evaluate the protective effect of ACEI on hypoxia conditions.ET-1, NO, ROS, and VEGF were detected by ELISA. HO-1, Nrf2, and Keap-1, the pivotal member in the Nrf2 signaling pathway, eNOS and PLVAP were detected in HEAECs treated with ACEI by immunofluorescence, qPCR, and western blotting.

RESULTS

The hypoxia ACEI or Nrf2 agonist groups showed higher cell viability compared with the hypoxia control group at 24 (61.75±1.16 or 61.23±0.59 vs. 44.24±0.58, both P < 0.05) and 48 h (41.85±1.19 or 59.64±1.13 vs. 22.98±0.25, both P < 0.05). ACEI decreased the levels of ET-1 and ROS under hypoxia challenge at 24 and 48 h (all P < 0.05); ACEI increased the VEGF and NO levels (all P < 0.05). ACEI promoted the expression level of eNOS, HO-1, Nrf2 and PLVAP but inhibited Keap-1 expression at the mRNA and protein levels (all P < 0.05). Blockade of the Nrf2 signaling pathway significantly decreased the expression level of PLVAP.

CONCLUSION

ACEI protects hypoxia-treated HEAECs by activating the Nrf2 signaling pathway and upregulating the expression of PLVAP.

NR3C2 mediates oxidised low-density lipoprotein-induced human coronary endothelial cells dysfunction via modulation of NLRP3 inflammasome activation

Nuclear receptor subfamily 3 group C member 2 (NR3C2) has been revealed to affect the progression of multiple inflammatory diseases, while NR3C2's efficacy in coronary artery disease (CAD) remains largely unsolved. The study intended to elucidate the possible mechanisms of NR3C2 in oxidised low density lipoprotein (ox-LDL)-induced inflammation in human coronary endothelial cells (HCAECs) via regulating NACHT, LRR, and PYD domains-containing protein 3 (NLRP3). Patients who underwent CT angiography or coronary angiography for suspected CAD in our hospital were collected. The patients were divided into the CAD and the non-CAD (NCAD) groups. The expression of NR3C2 and NLRP3 in the peripheral blood of patients in both groups was examined by RT-qPCR. HCAECs were treated with ox-LDL to establish the model. The expression of NR3C2 and NLRP3 in ox-LDL-induced HCAECs was tested by RT-qPCR. The proliferation of HCAECs was measured using CCK-8 assay, the apoptosis of HCAECs was assessed by flow cytometry, and the levels of inflammation-related factors IL-1β and IL-18 in the cell supernatant were evaluated by ELISA. The molecular mechanisms of these factors in the proliferation and apoptosis of HCAECs and in the inflammatory response were further determined by knockdown and overexpression systems. The relationship between NR3C2 and NLRP3 was determined by ChIP and luciferase activity assays and bioinformatics analysis. NR3C2 and NLRP3 levels were elevated in the serum of CAD patients. The ox-LDL treatment elevated NR3C2 levels, evoked apoptosis and inflammation, and impeded cell viability in HCAECs, whereas downregulation of NR3C2 increased cell viability and reduced apoptosis and inflammatory response in ox-LDL-induced inflammation in HCAECs. NR3C2 levels were positively correlated with NLRP3, and NR3C2 elevated NLRP3 expression through transcription. Overexpression of NLRP3 counteracted the impacts of silencing NR3C2 on cell viability, cell apoptosis, and inflammatory response in ox-LDL-induced HCAECs. Our research stresses that NR3C2 transcription promotes NLRP3 to induce inflammatory responses in ox-LDL-induced HCAECs.

Binding of human coronary artery endothelial cells to plasma-treated titanium dioxide nanotubes of different diameters

Nanoscale topography in improving vascular response in vitro was established previously on various titanium surfaces. In the present study different surface nanotopographies that is different diameters of titanium dioxide (TiO2 ) nanotubes (NTs) were fabricated by electrochemical anodization and conditioned with highly reactive gaseous oxygen plasma. The morphology of different diameter NTs was studied by scanning electron microscopy and atomic force microscopy, while changes in chemical composition on the surface before and after plasma treatment were determined by X-ray photoelectron spectroscopy. Performance of human coronary artery endothelial cells (HCAEC) on those conditioned surfaces was studied in regard to cell proliferation, released IL-6 protein and immunofluorescence microscopy (IFM). We show that HCAEC function is dependent on the diameter of the TiO2 NTs, functioning far less optimally when bound to 100 nm TiO2 NTs as compared to Ti foil, 15 nm NTs or 50 nm NTs. There were improved, morphological cell shape changes, observed with IFM, between HCAEC growing on oxygen-rich plasma-treated versus nontreated 100 nm NTs. These endothelialized conditioned Ti nanosurfaces could elucidate optimization conditions necessary for vascular implants in coronary arteries.