Hypoxia and reoxygenation do not upregulate adhesion molecules and natural killer cell adhesion on human endothelial cells in vitro |
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Authors: | Christine F. Maurus, D rthe Schmidt, M rten K. J. Schneider, Marko I. Turina, J rg D. Seebach,Gregor Zü nd |
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Affiliation: | a Clinic for Cardiovascular Surgery, University Hospital Zürich, Rämistr. 100, F LAB 39, CH-8091, Zürich, Switzerland b Laboratory for Transplantation Immunology, University Hospital Zürich, Rämistr. 100, F LAB 39, CH-8091, Zürich, Switzerland |
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Abstract: | Objectives: Ischemia/reperfusion injury is characterized by endothelial cell activation leading to increased expression of adhesion molecules such as inter-cellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, endothelial- and platelet-selectin (E- and P-selectin), and to the subsequent recruitment of leukocytes. The aim of the present study was to investigate the respective effects of a proinflammatory cytokine (tumor necrosis factor alpha , TNF-), hypoxia and/or reoxygenation on adhesion molecule expression and natural killer (NK) cell adhesion in an in vitro model of I/R. Methods: Human aortic endothelial cells (HAEC) were stimulated in vitro for 8h with TNF- (1000 U/ml) and exposed to hypoxia (1% O2), reoxygenation (21% O2) or different combinations thereof. Cell surface expression of ICAM-1, VCAM-1 and E-/P-selectin on HAEC was analyzed by flow cytometry, and culture supernatants were tested for soluble adhesion molecules by ELISA. Rolling adhesion of NK cells on HAEC was determined using a rotating assay. Results: Untreated HAEC constitutively expressed ICAM-1 on their surface but neither expressed E-/P-selectin, VCAM-1, nor shedded soluble adhesion molecules. Exposure of HAEC to hypoxia or hypoxia and reoxygenation did not upregulate cell surface expression or shedding of adhesion molecules. In contrast, TNF- significantly upregulated cell surface expression of ICAM-1, VCAM-1, and E-/P-selectin and led to the shedding of ICAM-1 and E-selectin. Combined treatment of HAEC with TNF-, hypoxia and reoxygenation reduced E-/P-selectin surface expression and enhanced E-selectin shedding, but did not further influence ICAM-1 and VCAM-1. Soluble VCAM-1 was not detected. NK cell adhesion on HAEC increased 4-fold after TNF- stimulation, but was not affected by hypoxia or hypoxia and reoxygenation. Conclusions: Both the expression of endothelial adhesion molecules and rolling NK cell adhesion was upregulated by TNF- but not by hypoxia alone or hypoxia followed by reoxygenation supporting the view that anti-inflammatory treatment may reduce ischemia/reperfusion injury. |
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Keywords: | Ischemia/reperfusion injury Hypoxia/reoxygenarion Human aortic endothelial cells Adhesion molecules Natural killer cells Tumor necrosis factor alpha |
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