Objective: To determine whether human vascular endothelial cells produce tumor necrosis factor-alpha (TNF-alpha) after stimulation with proinflammatory cytokines and bacterial lipopolysaccharides (LPS).
Design: Prospective, in vitro repeated-measurements analysis of cellular responses.
Setting: Research laboratory in an academic medical center.
Subjects: Human umbilical vein endothelial cells (HUVECs).
Interventions: HUVECs were incubated with interferon-gamma (IFN-gamma), interleukin-1beta (IL-1beta), and LPS, or their different combinations for 2 to 48 hrs.
Measurements and main results: TNF-alpha was measured by time-resolved immunofluorometric assay. Unstimulated HUVECs did not produce detectable amounts of TNF-alpha, but IFN-gamma, IL-1beta, and LPS when added together induced TNF-alpha production of HUVECs in a time-dependent manner. Immunofluorescent staining confirmed that the TNF-alpha was produced by endothelial cells. IFN-gamma, IL-1beta, or LPS alone did not induce TNF-alpha production, whereas IFN-gamma and IL-1beta in combination were able to induce TNF-alpha production to some extent, and the production could be further increased with LPS. TNF-alpha messenger RNA expression was detected with reverse transcriptase-coupled polymerase chain reaction in stimulated, but not in unstimulated, HUVECs.
Conclusions: HUVECs are capable of producing TNF-alpha after proinflammatory cytokine stimulation and may therefore contribute to the increased amount of TNF-alpha found in pathologic states such as septic shock.