Regulation of indoleamine 2,3-dioxygenase in primary human saphenous vein endothelial cells

Abstract

Background

Indoleamine 2,3-dioxygenase (IDO) is an enzyme associated with the regulation of immune responses. Cytokines such as IFNγ induce its expression in endothelial cells originating from immune-privileged sites. In this study, we investigate regulators of IDO in primary endothelial cells from a non-immune-privileged site and determine whether IDO expression affects immune cell behavior.

Methods

IDO expression was determined using real-time quantitative polymerase chain reaction and immunoblotting. IDO activity was estimated using an IDO enzyme assay. Primary cells were transfected using microporation, and T-cell migration was determined using a cell transmigration assay.

Results

IDO is expressed in human saphenous vein endothelial cells after stimulation with IFNγ but not after treatment with TNFα, IL-1β, IL-2, IL-4, IL-6, or IL-10. VEGFβ and heparin negatively regulate IFNγ-driven increases in IDO. Overexpression of IDO in endothelial cells does not affect transmigration of T-cells.

Conclusion

IDO is expressed in human saphenous vein endothelial cells after stimulation with IFNγ. Heparin and angiogenesis stimulators such as VEGFβ negatively regulate its expression.

Keywords:

• IFNγ
• VEGFβ
• endothelium
• inflammation
• HSVEC

Supplementary materials

Figure S1 IDO dose–response curve.

Note: Results are presented as means + standard deviation of one experiment.

Figure S2 IDO activity after treatment of human saphenous vein endothelial cells with cytokines for 2 days.

Note: Results are presented as means + standard deviation of one experiment.

Acknowledgments

This study was funded by the British Heart Foundation (BHF).

Disclosure

The authors report no conflicts of interest in this work.