title: Localization of collagen XVIII and endostatin in the human eye.
abstract: OBJECTIVE
  To investigate the localization of endostatin, a potent angiogenesis inhibitor, and its progenitor collagen XVIII in the human eye.
  
  
  METHODS
  Twelve normal human eyes were investigated. Immunohistochemistry of the anterior and posterior eye segment was performed using a polyclonal endostatin and collagen XVIII antibody and a monoclonal collagen XVIII antibody. Specificity of the antibodies was confirmed by Western blot analysis.
  
  
  RESULTS
  The antibody against collagen XVIII stained Bowman's membrane, the lens capsule, the trabecular meshwork, and all epithelial and endothelial basal membranes in the anterior and posterior eye segment. In contrast, the antibody against endostatin showed a more distinct staining pattern. Intense intracellular staining for endostatin was present in the lens epithelium and in the non-pigmented epithelium of the ciliary body. Extracellular presence of endostatin could be detected in the lens capsule and all border membranes lining the aqueous humor including the anterior surface of the iris. The choroid was unstained. In the retina, staining was restricted to the inner limiting membrane and to endothelial cells of larger vessels.
  
  
  CONCLUSIONS
  Our results show that there is a ring of specifically endostatin expressing structures forming a "barrier" around the anterior chamber and the vitreous. This might physiologically prevent vessels from sprouting into these avascular compartments.
authors.affiliation: University Eye Hospital, Ludwig-Maximilians University, Munich, Germany.
authors.forename: Anne V
authors.initials: AV
authors.lastname: Ohlmann
authors.forename: Andreas
authors.initials: A
authors.lastname: Ohlmann
authors.forename: Ulrich
authors.initials: U
authors.lastname: Welge-Lüssen
authors.forename: Christian A
authors.initials: CA
authors.lastname: May
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D043170:Collagen Type XVIII / Q000378:metabolism*; D043169:Endostatins / Q000378:metabolism*; D005123:Eye / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged
chemical_list: D043170:Collagen Type XVIII; D043169:Endostatins