Exposing endothelial cells to tumor necrosis factor-α and peripheral blood mononuclear cells damage endothelial integrity via interleukin-1ß by degradation of vascular endothelial-cadherin.
OBJECTIVE
We demonstrated previously that the administration of tumor necrosis factor alpha (TNF-α) for the treatment of solid tumors enhanced the response to chemotherapy by augmenting intratumoral drug accumulation. TNF-α changes the integrity of the endothelial cell monolayer in combination with interferon gamma (IFN-γ), which is further enhanced by the addition of peripheral blood mononuclear cells (PBMCs). The improved effect of PBMCs was mostly induced by the endogenous production of interleukin-1beta (IL-1ß) after TNF-α stimulation. In the current study, we demonstrate that exposing endothelial cells to TNF-α and PBMCs mediates the loss of vascular endothelial (VE)-cadherin, an important adherens junction protein for maintaining endothelial integrity, through endogenous IL-1ß. This loss increases permeability of the endothelial layer, thereby explaining the augmented passage of chemotherapeutics into the tumor.


METHODS
Human umbilical vein endothelial cells were exposed to TNF-α, IFN-γ, PBMCs, or IL-1ß, and the effects on the endothelial integrity were assessed by morphological changes and permeability changes with the use of fluorescein isothiocyanate-labeled bovine serum albumin flux. The loss of VE-cadherin was assessed using immunofluorescence, western blotting, and polymerase chain reaction.


RESULTS
Incubating endothelial cells with TNF-α, IFN-γ, and PBMCs increased cell elongation, gap formation, and subsequently the permeability of fluorescein isothiocyanate-labeled bovine serum albumin compared with control or TNF-α and IFN-γ-treated cells (P < .05). When PBMCs were replaced with IL-1ß, identical changes were observed. These changes in integrity were associated with a loss of VE-cadherin at the membrane.


CONCLUSIONS
We conclude that VE-cadherin is lost at the membrane when endothelial cells are exposed to TNF-α, IFN-γ, and PBMCs, which results in loss of integrity. IL-1ß can mimic the effects of PBMCs, indicating a dominant role of endogenously produced IL-1ß in this process.
Laboratory of Experimental Surgical Oncology, Department of Surgical Oncology, Erasmus MC, Rotterdam, The Netherlands. Electronic address: a.seynhaeve@erasmusmc.nl.
Ann L B
AL
Seynhaeve
Laboratory of Experimental Surgical Oncology, Department of Surgical Oncology, Erasmus MC, Rotterdam, The Netherlands.
Joost A P
JA
Rens
Laboratory of Experimental Surgical Oncology, Department of Surgical Oncology, Erasmus MC, Rotterdam, The Netherlands.
Debby
D
Schipper
Laboratory of Experimental Surgical Oncology, Department of Surgical Oncology, Erasmus MC, Rotterdam, The Netherlands; Institut Gustave Roussy, Villejuif, Paris-Sud, France.
Alexander M M
AM
Eggermont
Laboratory of Experimental Surgical Oncology, Department of Surgical Oncology, Erasmus MC, Rotterdam, The Netherlands.
Timo L M
TL
Ten Hagen
D015703:Antigens, CD / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000099152:Cadherin 5
D015703:Antigens, CD; D000970:Antineoplastic Agents; D015415:Biomarkers; D015820:Cadherins; D007371:Interferon-gamma; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D000099152:Cadherin 5