Anchoring fusion thrombomodulin to the endothelial lumen protects against injury-induced lung thrombosis and inflammation.
BACKGROUND
Endothelial thrombomodulin (TM) regulates thrombosis and inflammation. Diverse forms of pulmonary and vascular injury are accompanied by down-regulation of TM, which aggravates tissue injury. We postulated that anchoring TM to the endothelial surface would restore its protective functions.


OBJECTIVE
To design an effective and safe strategy to treat pulmonary thrombotic and inflammatory injury.


METHODS
We synthesized a fusion protein, designated scFv/TM, by linking the extracellular domain of mouse TM to a single-chain variable fragment of an antibody to platelet endothelial cell adhesion molecule-1 (PECAM-1). The targeting and protective functions of scFv/TM were tested in mouse models of lung ischemia-reperfusion and acute lung injury (ALI) caused by intratracheal endotoxin and hyperoxia, both of which caused approximately 50% reduction in the endogenous expression of TM.


RESULTS
Biochemical assays showed that scFv/TM accelerated protein C activation by thrombin and bound mouse PECAM-1 and cytokine high mobility group-B1. After intravenous injection, scFv/TM preferentially accumulated in the mouse pulmonary vasculature. In a lung model of ischemia-reperfusion injury, scFv/TM attenuated elevation of early growth response-1, inhibited pulmonary deposition of fibrin and leukocyte infiltration, and preserved blood oxygenation more effectively than soluble TM. In an ALI model, scFv/TM, but not soluble TM, suppressed activation of nuclear factor-kappaB, inflammation and edema in the lung and reduced mortality without causing hemorrhage.


CONCLUSIONS
Targeting TM to the endothelium using an scFv anchor enhances its antithrombotic and antiinflammatory effectiveness in models of ALI.
Ding
Bi-Sen
BS
Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Hong
Nankang
N
Christofidou-Solomidou
Melpo
M
Gottstein
Claudia
C
Albelda
Steven M
SM
Cines
Douglas B
DB
Fisher
Aron B
AB
Muzykantov
Vladimir R
VR