title: Influence of endotoxin-mediated retinal inflammation on phenotype of diabetic retinopathy in Ins2 Akita mice.
abstract: OBJECTIVE
  To evaluate the impact of systemic exposure to bacterial lipopolysaccharide (LPS) on a rodent model of background diabetic retinopathy.
  
  
  METHODS
  Toll-like receptor 4 (TLR4)-mediated systemic inflammation was induced in Ins2(Akita) heterozygotes and age-matched C57BL6/J-Ins2(+) littermates by single or repeated intraperitoneal injections of the TLR4 ligand LPS (9 µg/g body weight). 24 hours after a single injection in 7-week-old mice retinal Il1b, Tnfa and Vegf transcripts were measured with real-time PCR. Vascular endothelial growth factor (VEGF) protein levels were evaluated with bead-based immunoassay. Leukostasis and endothelial injury were assessed in retinal wholemounts following perfusion with rhodamine or FITC conjugated concanavalin A to label leukocytes and propidium iodide to label dead or injured cells. In mice which had received three fortnightly injections between 10 and 16 weeks of age, retinal thicknesses and vascular structure were evaluated at 17-18 weeks of age using optical coherence tomography (OCT) and fluorescein angiography. Retinal architecture was assesed using resin-based histology.
  
  
  RESULTS
  Compared with normoglycaemic controls, systemic LPS exposure in Ins2(Akita) mice was associated with a 3.5-fold increase in endothelial cell injury and attenuated leukostasis in the retinal vasculature. Hyperglycaemia or acute LPS inflammation did not increase retinal VEGF content. Thinning (10-13 µm) of posterior retina was detected with OCT 2 weeks after repeated exposure to LPS in Ins2(Akita) mice but not in normoglycaemic controls. Capillary networks and retinal morphology were unaffected by recurrent LPS inflammation in Ins2(Akita) and control mice.
  
  
  CONCLUSIONS
  In hyperglycaemic mice, exposure to systemic LPS was associated with two hallmark pathologies of early background diabetic retinopathy, namely, the injury of capillary endothelium and in vivo thinning of the retina.
authors.affiliation: Centre for Ophthalmology and Visual Science, University of Western Australia, , Crawley, Western Australia, Australia.
authors.forename: Nermina N
authors.initials: NN
authors.lastname: Vagaja
authors.forename: Nicolette
authors.initials: N
authors.lastname: Binz
authors.forename: Samuel
authors.initials: S
authors.lastname: McLenachan
authors.forename: Elizabeth P
authors.initials: EP
authors.lastname: Rakoczy
authors.forename: Paul G
authors.initials: PG
authors.lastname: McMenamin
mesh_terms: D000818:Animals; D003930:Diabetic Retinopathy / Q000378:metabolism / Q000473:pathology*; D004195:Disease Models, Animal; D005451:Fluorescein Angiography; D007274:Injections, Intraperitoneal; D008070:Lipopolysaccharides / Q000633:toxicity*; D051379:Mice; D008810:Mice, Inbred C57BL; D016133:Polymerase Chain Reaction; D012160:Retina / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000502:physiology*; D041623:Tomography, Optical Coherence; D042442:Vascular Endothelial Growth Factors / Q000378:metabolism
chemical_list: D008070:Lipopolysaccharides; D051197:Toll-Like Receptor 4; D042442:Vascular Endothelial Growth Factors
keywords: Inflammation; Retina