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Innate Immun. 2011 Feb;17(3):283-92. doi: 10.1177/1753425910369849. Epub 2010 Apr 27.

Chylomicrons combined with endotoxin moderate microvascular permeability.

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University of California Surgical Research Laboratory at San Francisco General Hospital, University of California at San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143-0104, USA.


Triglyceride-rich lipoprotein-bound endotoxin (CM-LPS) inhibits the host innate immune response to sepsis by attenuating the hepatocellular response to pro-inflammatory cytokine stimulation. This 'cytokine tolerance' in hepatocytes is a transient, receptor-dependent process that correlates with internalization of CM-LPS via low density lipoprotein (LDL) receptors. Since endothelial cells are integral to the immune response and similarly express LDL receptors, we hypothesized that CM-LPS could be internalized and ultimately attenuate the deleterious effects of pro-inflammatory molecules like tumor necrosis factor-α (TNF-α) and platelet activating factor (PAF) on endothelial permeability. Here, we show that CM-LPS complexes induce cytokine tolerance in endothelial cells. In rats, TNF-α increased hydraulic conductivity 2.5-fold over baseline and PAF increased it 5-fold; but, pretreatment with CM-LPS or an attenuated analog (CM-LPS*) inhibited these changes. Nuclear/cytoplasmic levels of p65 were reduced after TNF-α-stimulation in endothelial cell monolayers pretreated with CM-LPS, a finding consistent with inhibition of nuclear factor (NF)-κB translocation. Also consistent with inhibition was stabilized intercellular adhesion, as illustrated with antibody to VE-cadherin using confocal microscopy. These results provide additional support for the integral role of lipoproteins in the innate immune response to infection and lend further credence to developing lipid-based therapy for Gram-negative sepsis.

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