Hexa-acylated LPS-lipid A deploys the appropriate level of fibrin to confer protection through MyD88

Abstract

Objectives: Fibrin has been demonstrated to function protectively against pathogens in our previous studies, but we observed that a very high level of fibrin played a negative role during infection. We performed this research to address the complication.

Methods: After infection, mice were monitored daily and harvested on day 4. The fibrin levels within the tissue samples were quantified by Western-blot. The in situ assay was used to detect plasminogen activators, protein C-ase and prothrombinase activation. PT-PCR was used to test coagulation factors expression.

Results: Mice treated with Coumadin showed that the protection correlates with fibrin levels. By interacting with Toll-like receptor 4, the hexa-acylated lipopolysaccharide, although not the tetra-acylated lipopolysaccharide, activates coagulation and regulates plasminogen activator inhibitor 1, thrombin activatable fibrinolysis inhibitor and thrombomodulin expression through myeloid differentiation factor 88, leading to plasminogen activators, protein C-ase and prothrombinase activation and fibrin formation. Because of the regulation, fibrin formation was controlled to deposit appropriate levels and confer protection.

Conclusions: We demonstrated that the appropriate level of fibrin formation was deployed by hexa-acylated LPS-lipid A through myeloid differentiation factor 88 to confer protection.

Keywords: Lipopolysaccharide; Yersinia pestis; coagulation; fibrin.