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Mechanisms of endotoxin tolerance in human intestinal microvascular endothelial cells. J Immunol 2003 Jun 15;170(12):5956-64



Pubmed ID




Scopus ID

2-s2.0-0037605943   60 Citations


Lipopolysaccharide (endotoxin) tolerance is well described in monocytes and macrophages, but is less well characterized in endothelial cells. Because intestinal microvascular endothelial cells exhibit a strong immune response to LPS challenge and play a critical regulatory role in gut inflammation, we sought to characterize the activation response of these cells to repeated LPS exposure. Primary cultures of human intestinal microvascular endothelial cells (HIMEC) were stimulated with LPS over 6-60 h and activation was assessed using U937 leukocyte adhesion, expression of E-selectin, ICAM-1, VCAM-1, IL-6, IL-8, manganese superoxide dismutase, HLA-DR, and CD86. Effect of repeat LPS stimulation on HIMEC NF-kappaB and mitogen-activated protein kinase (MAPK) activation, generation of superoxide anion, and Toll-like receptor 4 expression was characterized. LPS pretreatment of HIMEC for 24-48 h significantly decreased leukocyte adhesion after subsequent LPS stimulation. LPS pretreatment inhibited expression of E-selectin, VCAM-1, IL-6, and CD86, while ICAM-1, IL-8, and HLA-DR were not altered. Manganese superoxide dismutase expression increased with repeated LPS stimulation, with a reduction in intracellular superoxide. NF-kappaB activation was transiently inhibited by LPS pretreatment for 6 h, but not at later time points. In contrast, p44/42 MAPK, p38 MAPK, and c-Jun N-terminal kinase activation demonstrated inhibition by LPS pretreatment 24 or 48 h prior. Toll-like receptor 4 expression on HIMEC was not altered by LPS. HIMEC exhibit endotoxin tolerance after repeat LPS exposure in vitro, characterized by diminished activation and intracellular superoxide anion concentration, and reduced leukocyte adhesion. HIMEC possess specific mechanisms of immunoregulatory hyporesponsiveness to repeated LPS exposure.

Author List

Ogawa H, Rafiee P, Heidemann J, Fisher PJ, Johnson NA, Otterson MF, Kalyanaraman B, Pritchard KA Jr, Binion DG


Balaraman Kalyanaraman PhD Chair, Professor in the Biophysics department at Medical College of Wisconsin
Mary F. Otterson MD Professor in the Surgery department at Medical College of Wisconsin
Kirkwood A. Pritchard PhD Professor in the Surgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adjuvants, Immunologic
Antibodies, Monoclonal
Binding Sites, Antibody
Binding, Competitive
Cell Adhesion
Cell Adhesion Molecules
Cell Line
Cell Membrane
Dose-Response Relationship, Immunologic
Endothelium, Vascular
Immune Tolerance
Immunity, Mucosal
Intestinal Mucosa
Intracellular Fluid
MAP Kinase Signaling System
Membrane Glycoproteins
NF-kappa B
Reactive Oxygen Species
Receptors, Cell Surface
Toll-Like Receptor 4
Toll-Like Receptors
U937 Cells
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a