title: CD40 promotes the development of early diabetic retinopathy in mice.
abstract: OBJECTIVE
  Microangiopathy is a leading complication of diabetes that commonly affects the retina. Degenerate capillaries are a central feature of diabetic retinopathy. An inflammatory process has been linked to the development of diabetic retinopathy but its regulation is incompletely understood. Cluster of differentiation (CD) 40 is a member of the TNF receptor superfamily that promotes the development of certain inflammatory disorders. The role of CD40 in diabetic microangiopathy is unknown.
  
  
  METHODS
  B6 and Cd40−/− mice were administered streptozotocin to induce diabetes. Leucostasis was assessed using fluorescein isothiocyanate-conjugated concanavalin A. Retinal Icam1 and Cd40 mRNA levels were examined using real-time PCR. Protein nitration was assessed by immunohistochemistry. Histopathology was examined in the retinal vasculature. CD40 expression was assessed by flow cytometry and immunohistochemistry. Intercellular adhesion molecule 1 (ICAM-1) and nitric oxide synthase 2 (NOS2) were examined by immunoblot and/or flow cytometry. Nitric oxide production was examined by immunoblot and Griess reaction.
  
  
  RESULTS
  In mouse models of diabetes, Cd40−/− mice exhibited reduced retinal leucostasis and did not develop capillary degeneration in comparison with B6 mice. Diabetic Cd40−/− mice had diminished ICAM-1 upregulation and decreased protein nitration. Cd40 mRNA levels were increased in the retinas of diabetic B6 mice compared with non-diabetic controls. CD40 expression increased in retinal Müller cells, endothelial cells and microglia of diabetic animals. CD40 stimulation upregulated ICAM-1 in retinal endothelial cells and Müller cells. CD40 ligation upregulated NOS2 and nitric oxide production by Müller cells.
  
  
  CONCLUSIONS
  CD40-deficient mice were protected fromthe development of diabetic retinopathy. These mice exhibited diminished inflammatory responses linked to diabetic retinopathy. CD40 stimulation of retinal cells triggered these pro-inflammatory responses.
authors.forename: Jose-Andres C
authors.initials: JA
authors.lastname: Portillo
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Greene
authors.forename: Genevieve
authors.initials: G
authors.lastname: Okenka
authors.forename: Yanling
authors.initials: Y
authors.lastname: Miao
authors.forename: Nader
authors.initials: N
authors.lastname: Sheibani
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Kern
authors.forename: Carlos S
authors.initials: CS
authors.lastname: Subauste
mesh_terms: D000818:Animals; D003930:Diabetic Retinopathy / Q000209:etiology* / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism; D063928:Ependymoglial Cells / Q000378:metabolism; D005434:Flow Cytometry; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: C472643:Knl1 protein, human; D008869:Microtubule-Associated Proteins