Exploration and validation of the hub genes involved in hypoxia-induced endothelial-mesenchymal transition of systemic sclerosis

During the development of systemic sclerosis (SSc), endothelial-mesenchymal transition (EndoMT) has been shown to be one of the mechanisms leading to pulmonary fibrosis. However, the correlation between hypoxia and EndoMT was mostly unknown.R software was used to analyse differentially expressed genes (DEGs) in vascular endothelial cells under hypoxic conditions, and fibroblasts derived from SSc-related pulmonary fibrotic tissues, respectively. Using a web-based online Venn diagram tool, we analysed overlapping genes of DEGs between endothelial cells and fibroblasts. Finally, the protein-protein interaction network of EndoMT hub genes were constructed using the STRING database. The hub genes were knockdown by transfection of siRNAs in the hypoxia model of HULEC-5a cells constructed by liquid paraffin closure and then used to detect the effect on EndoMT-related biomarkers by western blot.In this study, we found that INHBA, DUSP1, NOX4, PLOD2, BHLHE40 were upregulated in SSc fibroblasts and hypoxic-treated endothelial cells, while VCAM1, RND3, CCL2, and TXNIP were downregulated. In the hypoxia model of HULEC-5a cells, the expression of these 9 hub genes was confirmed by western blot. In addition, through Spearman's correlation analysis and Western blot, we confirmed that these hub genes were closely related to the EndoMT-related markers. The mechanisms of these hypoxia-induced EndoMT hub genes may be related to TGF-β, Notch, Wnt, NF-κ B, TNF and mTOR signalling pathways.Our study provides new insights into the occurrence and development of SSc-related pulmonary fibrosis resulting from hypoxia-induced EndoMT.