Endoglin is not a mediator in 7-ketocholesterol-induced endothelial activation in liver sinusoidal endothelial cells in vitro

Background Endoglin (ENG) is expressed in liver sinusoidal endothelial cells (LSECs), where it regulates endothelial activation and inflammation. The 7-ketocholesterol (7-K), a cholesterol oxidation product, accumulates in the liver and induces endothelial dysfunction. ENG has been shown to play an important role in adhesion processes in other endothelial models but its role in LSECs upon 7-K exposure remains unclear. We hypothesized that 7-K treatment of LSECs would confirm the critical role of ENG in endothelial activation, potentially outweighing the contributions of the cell adhesion molecules VCAM-1 and ICAM-1. Methods Human LSECs were exposed to 25 µM 7-K. Protein expression and monocyte adhesion were assessed by flow cytometry, and soluble ENG was measured by ELISA. Results 7-K reduced ENG expression, while ICAM-1 was markedly upregulated. 7-K increased monocyte adhesion to LSECs, which was abrogated by ICAM-1, but not by ENG neutralization. Conclusion We showed that 7-K promotes a pro-inflammatory phenotype defined by ICAM-1, rather than ENG. Thus, we propose that individual roles of ENG, ICAM-1, and VCAM-1 must be carefully considered when studying endothelial dysfunction.