Neutrophil Gelatinase-Associated Lipocalin 2 Accelerates Hypoxia-Induced Endothelial Cell Injury via eNOS/NRF2 Signalling

(Pages: 435-444)
Yang Gu, Ph.D, 1Wei Sun, Ph.D, 2Zhuo Xu, Ph.D, 1Jing Wang, Ph.D, 1Xiao Hu, Ph.D, 1Zhou-Zhou Lu, Ph.D, 1Zhang Xi-Wen, Ph.D.,M.D., 1,*
Department of Cardiology, The Affiliated Huaian No. 1 People’s Hospital of Nanjing Medical University, Huai'an, Jiangsu, China
Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
Department of Cardiology, The Affiliated Huaian No. 1 People’s Hospital of Nanjing Medical University, Huai'an, Jiangsu, China
Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
*Corresponding Address: Department of Cardiology The Affiliated Huaian No. 1 People’s Hospital of Nanjing Medical University Huai’an Jiangsu China Email:gzh150108@163.com
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Gu Yang, Sun Wei, Xu Zhuo, Wang Jing, Hu Xiao, Lu Zhou-Zhou, Xi-Wen Zhang. Neutrophil Gelatinase-Associated Lipocalin 2 Accelerates Hypoxia-Induced Endothelial Cell Injury via eNOS/NRF2 Signalling . Cell J. 2021; 23(4): 435-444.

Abstract

Objective

Neutrophil gelatinase-associated lipocalin (NGAL), a lipocalin, is implicated in many cardiovascular diseases (CVD). The effect of NGAL on endothelial cells (ECs), particularly on ECs injured because of hypoxia, is unclear. In this study, we aim to explore the effect of NGAL in an EC injury in response to hypoxia.

Materials and Methods

In this experimental study, we isolated and cultured mouse heart ECs (MHECs). The EC injury model was established by exposure of the ECs to hypoxia for 24 hours. The ECs were treated with NGAL (30, 60, 120, 250 and 500 ng/ml). Cell inflammation and oxidative stress were detected by corresponding assays. Apoptotic cells were stained by the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay.

Results

NGAL increased the inflammatory response at the baseline level and further augmented the hypoxia-induced inflammation response. Reactive oxygen species (ROS) levels increased upon NGAL treatment, which caused antioxidase/oxidase imbalance. NGAL also exaggerated hypoxia-induced oxidative stress. The cell apoptosis rate also increased in both the NGAL-treated normoxic and hypoxic conditions. NGAL also reduced endothelial nitric oxide synthase (eNOS)-nitric oxide (NO) signalling, thus decreasing the expression and nuclear translocation of nuclear factor erythroid-2-related factor 2 (NRF2), which was confirmed by overexpression of NRF2.

Conclusion

NGAL exaggerates EC injury in both normoxic and hypoxic conditions by inhibiting the eNOS-NRF2 pathway.