title: Persistent inhibition of oxygen-induced retinal neovascularization by anthrax lethal toxin.
abstract: OBJECTIVE
  To evaluate the role of mitogen-activated protein kinase kinase (MKK) signaling in a mouse model of oxygen-induced retinopathy (OIR) that mimics retinopathy of prematurity (ROP).
  
  
  METHODS
  Postnatal day 7 mice were exposed to elevated oxygen for 5 days to induce retinopathy. Anthrax lethal toxin (LeTx), an MKK inhibitor, was injected into the vitreous after restoration to normoxia, and its effects on vascular growth were analyzed by whole mount immunofluorescence and confocal microscopy. Pericyte coverage was determined by PDGFR-β and α-SMA staining. Macrophage presence was determined by F4/80 staining. Vitreal cytokine secretion was measured by ELISA and multianalyte profiling.
  
  
  RESULTS
  Intravitreal injection of LeTx over a restricted time interval after return to normoxic conditions blocked the progression of OIR. This block was independent of vascular endothelial growth factor (VEGF) release and did not alter the release of cytokines and growth factors associated with OIR. VEGFR2 expression and activation were similarly unaffected. LeTx had no statistically significant effect on macrophage recruitment. LeTx sensitivity correlated with vessel maturity, extent of hypoxia, and growth of the deep vascular plexus network.
  
  
  CONCLUSIONS
  Correlation among pericyte coverage, deep vascular plexus growth, and hypoxia after LeTx treatment indicate immature vessels in a hypoxic environment are preferentially sensitive to LeTx-mediated MKK inhibition. The persistence of VEGF without concomitant induction of neovascular growth or revascularization of vaso-obliterated zones suggests MKK inhibition causes an inability of the cells that are present, or a failure to recruit cells able, to respond to proangiogenic stimuli. These results indicate the inhibition of MKK signaling presents a novel strategy for the inhibition of vascular retinopathies such as OIR and ROP.
authors: Laboratory of Cancer and Developmental Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA.
authors: Jennifer L
authors: JL
authors: Bromberg-White
authors: Elissa
authors: E
authors: Boguslawski
authors: Daniel
authors: D
authors: Hekman
authors: Eric
authors: E
authors: Kort
authors: Nicholas S
authors: NS
authors: Duesbery
mesh_terms: D042682:Angiopoietins / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000942:Antigens, Bacterial / Q000494:pharmacology*; D001427:Bacterial Toxins / Q000494:pharmacology*; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000166:cytology; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D007231:Infant, Newborn; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D010100:Oxygen / Q000009:adverse effects*; D015861:Retinal Neovascularization / Q000188:drug therapy* / Q000378:metabolism / Q000517:prevention & control*; D012178:Retinopathy of Prematurity / Q000188:drug therapy* / Q000378:metabolism / Q000517:prevention & control*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D042682:Angiopoietins; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D016207:Cytokines; D036341:Intercellular Signaling Peptides and Proteins; D042461:Vascular Endothelial Growth Factor A; C030325:anthrax toxin; C467480:vascular endothelial growth factor A, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D010100:Oxygen