title: The maintenance of lymphatic vessels in the cornea is dependent on the presence of macrophages.
abstract: OBJECTIVE
  It has been shown previously that the presence in the cornea of antigen-presenting cells (APC), such as macrophages (MPS) and lymphangiogenesis, is a risk for corneal transplantation. We sought to determine whether the existence of lymphatic vessels in the non-inflamed cornea is associated with the presence of MPS.
  
  
  METHODS
  Flat mounts were prepared from corneas of untreated C57BL/6, CD11b(-/-), F4/80(-/-), and BALB/c mice, and after suture placement or corneal transplantation, observed by immunofluorescence for the presence of lymphatic vessels using LYVE-1 as a marker of lymphatic endothelium. Innate immune cells were detected in normal mouse corneas using CD11b, F4/80, CD40, as well as MHC-class II. Digital images of the flat mounts were taken using a spot image analysis system, and the area covered by lymphatic vessels was measured using NIH Image software.
  
  
  RESULTS
  The number of spontaneous lymphatic vessels in C57BL/6 corneas was significantly greater than in BALB/c corneas (P = 0.03). There were more CD11b(+) (P < 0.01) and CD40(+), MHC-class II (+) cells in the C57BL/6 corneas than in BALB/c mouse corneas. MPS depletion via clodronate liposome in C57BL/6 mice led to fewer spontaneous lymphatic vessels and reduced inflammation-induced lymphangiogenesis relative to control mice. Mice deficient in CD11b or F4/80 had fewer spontaneous lymphatic vessels and less lymphangiogenesis than control C57BL/6 mice.
  
  
  CONCLUSIONS
  C57BL/6 mouse corneas have more endogenous CD11b(+) cells and lymphatic vessels. The endogenous lymphatic vessels, along with pro-inflammatory MPS, account for the high risk of corneal graft rejection in C57BL/6 mice. CD11b(+) and F4/80(+) MPS appear to have an important role in of the formation of new lymphatic vessels.
authors.affiliation: Department of Ophthalmology, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto, Japan. kmaruyam@koto.kpu-m.ac.jp
authors.forename: Kazuichi
authors.initials: K
authors.lastname: Maruyama
authors.forename: Toru
authors.initials: T
authors.lastname: Nakazawa
authors.forename: Claus
authors.initials: C
authors.lastname: Cursiefen
authors.forename: Yuko
authors.initials: Y
authors.lastname: Maruyama
authors.forename: Nico
authors.initials: N
authors.lastname: Van Rooijen
authors.forename: Patricia A
authors.initials: PA
authors.lastname: D'Amore
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kinoshita
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D003315:Cornea / Q000276:immunology* / Q000473:pathology; D016510:Corneal Neovascularization / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D016039:Corneal Transplantation; D004195:Disease Models, Animal; D004729:Endothelium, Lymphatic / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D006023:Glycoproteins / Q000378:metabolism; D006084:Graft Rejection / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D006085:Graft Survival; D042583:Lymphangiogenesis; D042601:Lymphatic Vessels / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D008264:Macrophages / Q000276:immunology*; D008297:Male; D026901:Membrane Transport Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL
chemical_list: D015415:Biomarkers; D006023:Glycoproteins; D026901:Membrane Transport Proteins; C492273:LYVE1 protein, mouse