title: Effects of a synthetic PEG-ylated Tie-2 agonist peptide on endotoxemic lung injury and mortality.
abstract: A synthetic 7-mer, HHHRHSF, was recently identified by screening a phage display library for binding to the Tie-2 receptor. A polyethylene-oxide clustered version of this peptide, termed vasculotide (VT), was reported to activate Tie-2 and promote angiogenesis in a mouse model of diabetic ulcer. We hypothesized that VT administration would defend endothelial barrier function against sepsis-associated mediators of permeability, prevent lung vascular leakage arising in endotoxemia, and improve mortality in endotoxemic mice. In confluent human microvascular endothelial cells, VT prevented endotoxin-induced (lipopolysaccharides, LPS O111:B4) gap formation, loss of monolayer resistance, and translocation of labeled albumin. In 8-wk-old male C57Bl6/J mice given a ∼70% lethal dose of endotoxin (15 mg/kg ip), VT prevented lung vascular leakage and reversed the attenuation of lung vascular endothelial cadherin induced by endotoxemia. These protective effects of VT were associated with activation of Tie-2 and its downstream mediator, Akt. Echocardiographic studies showed only a nonsignificant trend toward improved myocardial performance associated with VT. Finally, we evaluated survival in this mouse model. Pretreatment with VT improved survival by 41.4% (n = 15/group, P = 0.02) and post-LPS administration of VT improved survival by 33.3% (n = 15/group, P = 0.051). VT-mediated protection from LPS lethality was lost in Tie-2 heterozygous mice, in agreement with VT's proposed receptor specificity. We conclude that this synthetic Tie-2 agonist, completely unrelated to endogenous Tie-2 ligands, is sufficient to activate the receptor and its downstream pathways in vivo and that the Tie-2 receptor may be an important target for therapeutic evaluation in conditions of pathological vascular leakage.
authors.affiliation: Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Sascha
authors.initials: S
authors.lastname: David
authors.forename: Chandra C
authors.initials: CC
authors.lastname: Ghosh
authors.forename: Philipp
authors.initials: P
authors.lastname: Kümpers
authors.forename: Nelli
authors.initials: N
authors.lastname: Shushakova
authors.forename: Paul
authors.initials: P
authors.lastname: Van Slyke
authors.forename: Eliyahu V
authors.initials: EV
authors.lastname: Khankin
authors.forename: S Ananth
authors.initials: SA
authors.lastname: Karumanchi
authors.forename: Dan
authors.initials: D
authors.lastname: Dumont
authors.forename: Samir M
authors.initials: SM
authors.lastname: Parikh
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002199:Capillary Permeability / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D019446:Endotoxemia / Q000139:chemically induced / Q000401:mortality* / Q000517:prevention & control*; D004731:Endotoxins / Q000009:adverse effects*; D006801:Humans; D007124:Immunoenzyme Techniques; D008070:Lipopolysaccharides / Q000494:pharmacology; D055370:Lung Injury / Q000139:chemically induced / Q000401:mortality* / Q000517:prevention & control; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010446:Peptide Fragments / Q000138:chemical synthesis* / Q000494:pharmacology*; D011092:Polyethylene Glycols / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D042787:Receptor, TIE-2 / Q000819:agonists*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015996:Survival Rate
chemical_list: D004731:Endotoxins; D008070:Lipopolysaccharides; D010446:Peptide Fragments; D012333:RNA, Messenger; D011092:Polyethylene Glycols; D042787:Receptor, TIE-2