Low-level endotoxin induces potent inflammatory activation of human blood vessels: inhibition by statins.
BACKGROUND
Low-level endotoxemia (ie, >or=50 pg/mL) in apparently healthy subjects was recently identified as a powerful, independent risk factor for atherosclerosis.


RESULTS
We treated human saphenous veins (HSVs) with low levels of endotoxin. Release of the proinflammatory chemokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) was measured by ELISA. Superoxide was determined by using the fluorescent probe dihydroethidium (HE), and monocyte binding was assessed with calcein-labeled U-937 cells. Three- to 4-fold increases in MCP-1 and IL-8 release were observed at endotoxin concentrations of 100 pg/mL; these increases were inhibited by the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor atorvastatin. Studies in cultured endothelial cells suggest that the mechanism is related to inhibition of isoprenylation (ie, geranylgeranylation) rather than cholesterol formation. Endotoxin produced dose-dependent increases in HE fluorescence that were inhibited by the superoxide dismutase mimics Tiron and MnTBAP. Endotoxin potently induced U-937 cell binding to HSV; binding was inhibited by both Tiron and atorvastatin. Toll-like receptor-4 expression was detected in cultured HSV endothelial and smooth muscle cells and in intact HSV.


CONCLUSIONS
Clinically relevant levels of endotoxin, as reported in ambulatory populations, have profound inflammatory effects on intact HSV. Inhibition of endotoxin-induced vascular inflammation might contribute to the beneficial effects of statins in treating atherosclerosis.
Rice
James B
JB
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, IA 52242, USA.
Stoll
Lynn L
LL
Li
Wei-Gen
WG
Denning
Gerene M
GM
Weydert
Jamie
J
Charipar
Elizabeth
E
Richenbacher
Wayne E
WE
Miller
Francis J
FJ
Weintraub
Neal L
NL
D001808:Blood Vessels / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D045744:Cell Line, Tumor; D018932:Chemokine CCL2 / Q000378:metabolism; D003331:Coronary Vessels / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004731:Endotoxins / Q000037:antagonists & inhibitors* / Q000276:immunology*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D007249:Inflammation / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control; D016209:Interleukin-8 / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D012501:Saphenous Vein / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D020298:U937 Cells / Q000378:metabolism
D018932:Chemokine CCL2; D004731:Endotoxins; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D016209:Interleukin-8