title: Lymphatic vessels in vascularized human corneas: immunohistochemical investigation using LYVE-1 and podoplanin.
abstract: OBJECTIVE
  To determine whether lymphatic vessels exist in vascularized human corneas, by using immunohistochemistry with novel markers for lymphatic endothelium.
  
  
  METHODS
  Human corneas exhibiting neovascularization secondary to keratitis, transplant rejection, trauma, and limbal insufficiency (n = 21) were assessed for lymphatic vessel content by conventional transmission electron microscopy and by immunostaining and immunoelectron microscopy with antibodies specific for the lymphatic endothelial markers, lymphatic vessel endothelial hyaluronan receptor (LYVE-1) and the 38-kDa integral membrane glycoprotein podoplanin. In addition, corneas were stained for the lymphangiogenic growth factor VEGF-C, and its receptor VEGFR3 by immunohistochemistry and in situ RNA hybridization, respectively.
  
  
  RESULTS
  Thin-walled, erythrocyte-free vessels staining with lymphatic markers (LYVE-1 and podoplanin) were found to constitute 8% of all vessels, to be more common in the early course of neovascularization, to be always associated with blood vessels and stromal inflammatory cells, and to correlate significantly with the degree of corneal hemangiogenesis (r = 0.6; P = 0.005). VEGF-C, VEGFR3, podoplanin, and LYVE-1 colocalized on the endothelial lining of lymphatic vessels. With immunogold labeling, LYVE-1 and podoplanin antigen were found on endothelial cells lining vessels with ultrastructural features of lymph vessels.
  
  
  CONCLUSIONS
  Immunohistochemistry with novel lymph-endothelium markers and ultrastructural analyses indicate the existence of lymphatic vessels in vascularized human corneas. Human corneal lymphangiogenesis appears to be correlated with the degree of corneal hemangiogenesis and may at least partially be mediated by VEGF-C and its receptor VEGFR3.
authors.affiliation: Department of Ophthalmology and. Nikolaus-Fiebiger-Zentrum for Molecular Medicine, University of Erlangen-Nürnberg, Erlangen, Germany. cursiefen@vision.eri.harvard.edu
authors.forename: Claus
authors.initials: C
authors.lastname: Cursiefen
authors.forename: Ursula
authors.initials: U
authors.lastname: Schlötzer-Schrehardt
authors.forename: Michael
authors.initials: M
authors.lastname: Küchle
authors.forename: Lydia
authors.initials: L
authors.lastname: Sorokin
authors.forename: Silvana
authors.initials: S
authors.lastname: Breiteneder-Geleff
authors.forename: Kari
authors.initials: K
authors.lastname: Alitalo
authors.forename: David
authors.initials: D
authors.lastname: Jackson
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D003315:Cornea / Q000098:blood supply*; D016510:Corneal Neovascularization / Q000378:metabolism* / Q000473:pathology; D016228:Endothelial Growth Factors / Q000378:metabolism; D004729:Endothelium, Lymphatic / Q000378:metabolism; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D008208:Lymphatic System / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000378:metabolism; D042582:Vascular Endothelial Growth Factor C; D040321:Vascular Endothelial Growth Factor Receptor-3; D033921:Vesicular Transport Proteins; D000098853:Podoplanin
chemical_list: D015415:Biomarkers; D016228:Endothelial Growth Factors; D006023:Glycoproteins; D018960:Hyaluronan Receptors; D008562:Membrane Glycoproteins; D020794:Receptor Protein-Tyrosine Kinases; D017978:Receptors, Growth Factor; D042582:Vascular Endothelial Growth Factor C; D040321:Vascular Endothelial Growth Factor Receptor-3; D033921:Vesicular Transport Proteins; C119248:LYVE1 protein, human; C117468:PDPN protein, human; D000098853:Podoplanin