Chylomicrons combined with endotoxin moderate microvascular permeability

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Triglyceride-rich lipoprotein-bound endotoxin (CM-LPS) impairs innate immune responses in sepsis by inducing "cytokine tolerance" in hepatocytes.
• This tolerance is mediated by low-density lipoprotein (LDL) receptor-dependent internalization of CM-LPS.
• Endothelial cells, crucial for immune responses and expressing LDL receptors, are potential targets for CM-LPS effects.

Purpose of the Study:

• To investigate whether CM-LPS can induce cytokine tolerance in endothelial cells.
• To determine if CM-LPS can attenuate the effects of pro-inflammatory molecules like tumor necrosis factor-α (TNF-α) and platelet-activating factor (PAF) on endothelial permeability.

Main Methods:

• Endothelial cell monolayers were pretreated with CM-LPS or an attenuated analog (CM-LPS*).
• Effects of TNF-α and PAF on hydraulic conductivity were measured in rats.
• Nuclear factor-kappa B (NF-κB) p65 translocation and VE-cadherin stability were assessed using confocal microscopy.

Main Results:

• CM-LPS induced cytokine tolerance in endothelial cells.
• Pretreatment with CM-LPS or CM-LPS* inhibited TNF-α- and PAF-induced increases in hydraulic conductivity in rats.
• CM-LPS pretreatment reduced TNF-α-induced NF-κB p65 translocation and stabilized intercellular adhesion.

Conclusions:

• Lipoproteins play a key role in the innate immune response to infection.
• CM-LPS can attenuate pro-inflammatory effects on endothelial cells, suggesting potential for lipid-based therapies in Gram-negative sepsis.