Vascular immunotargeting to endothelial determinant ICAM-1 enables optimal partnering of recombinant scFv-thrombomodulin fusion with endogenous cofactor.
The use of targeted therapeutics to replenish pathologically deficient proteins on the luminal endothelial membrane has the potential to revolutionize emergency and cardiovascular medicine. Untargeted recombinant proteins, like activated protein C (APC) and thrombomodulin (TM), have demonstrated beneficial effects in acute vascular disorders, but have failed to have a major impact on clinical care. We recently reported that TM fused with an scFv antibody fragment to platelet endothelial cell adhesion molecule-1 (PECAM-1) exerts therapeutic effects superior to untargeted TM. PECAM-1 is localized to cell-cell junctions, however, whereas the endothelial protein C receptor (EPCR), the key co-factor of TM/APC, is exposed in the apical membrane. Here we tested whether anchoring TM to the intercellular adhesion molecule (ICAM-1) favors scFv/TM collaboration with EPCR. Indeed: i) endothelial targeting scFv/TM to ICAM-1 provides ~15-fold greater activation of protein C than its PECAM-targeted counterpart; ii) blocking EPCR reduces protein C activation by scFv/TM anchored to endothelial ICAM-1, but not PECAM-1; and iii) anti-ICAM scFv/TM fusion provides more profound anti-inflammatory effects than anti-PECAM scFv/TM in a mouse model of acute lung injury. These findings, obtained using new translational constructs, emphasize the importance of targeting protein therapeutics to the proper surface determinant, in order to optimize their microenvironment and beneficial effects.
Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America ; Center for Targeted Therapeutics and Translational Nanomedicine, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America ; Department of Emergency Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
Colin F
CF
Greineder
Ann-Marie
AM
Chacko
Sergei
S
Zaytsev
Blaine J
BJ
Zern
Ronald
R
Carnemolla
Elizabeth D
ED
Hood
Jingyan
J
Han
Bi-Sen
BS
Ding
Charles T
CT
Esmon
Vladimir R
VR
Muzykantov
D055371:Acute Lung Injury / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D000818:Animals; D015703:Antigens, CD / Q000276:immunology*; D002460:Cell Line; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D000074283:Endothelial Protein C Receptor; D004730:Endothelium, Vascular / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology*; D007365:Intercellular Junctions / Q000187:drug effects / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D058990:Molecular Targeted Therapy; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000276:immunology; D011486:Protein C / Q000819:agonists / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000276:immunology*; D057127:Single-Chain Antibodies / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology; D018180:Thrombomodulin / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*
D015703:Antigens, CD; D000074283:Endothelial Protein C Receptor; D018796:Immunoconjugates; C478370:PROCR protein, human; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011486:Protein C; D011956:Receptors, Cell Surface; D057127:Single-Chain Antibodies; D018180:Thrombomodulin; D018799:Intercellular Adhesion Molecule-1