title: Myocilin in the trabecular meshwork of eyes with primary open-angle glaucoma.
abstract: BACKGROUND
  Mutations in myocilin, a 55-57 kDa secreted glycoprotein, are causative for some forms of primary open-angle glaucoma (POAG). In vitro studies indicate that myocilin can modulate the hydrodynamic outflow resistance in the trabecular meshwork (TM) and that elevated amounts of myocilin can obstruct the TM outflow system in POAG. In this study, we analyzed the localization of myocilin in the trabecular meshwork (TM) of eyes with primary open-angle glaucoma (POAG), and compared it with that of normal eyes.
  
  
  METHODS
  Immunohistochemistry for myocilin was performed in the eyes of human donors (nine normal and 14 with POAG, including one with steroid-induced glaucoma).
  
  
  RESULTS
  Staining for myocilin was observed in the extracellular spaces of the juxtacanalicular tissue (JCT) in all normal eyes. Some normal eyes did also show cytoplasmic staining for myocilin in TM cells. In the eyes of six donors with POAG, staining of the JCT was more widespread and intense than in normal eyes. In the other eyes with POAG, immunoreactivity for myocilin in the JCT was not markedly different to that of normal eyes. Staining intensity in the JCT of POAG eyes did not obviously correlate with intraocular pressure or clinical severity. In the eyes of one patient with steroid-induced POAG, cells of the TM, Schlemm's canal endothelium, and the anterior stroma of the iris showed an immunoreactivity for myocilin which was considerably more intense than in normal eyes, or in the eyes with other forms of POAG.
  
  
  CONCLUSIONS
  In some cases of POAG, the structural changes in the JCT include an increase in myocilin in the extracellular pathways of aqueous humor. Treatment with steroids appears to increase myocilin synthesis in TM and iris of human eyes in situ.
authors: Institute of Human Anatomy and Embryology, University of Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany.
authors: Dirk D
authors: DD
authors: Konz
authors: Cassandra
authors: C
authors: Flügel-Koch
authors: Andreas
authors: A
authors: Ohlmann
authors: Ernst R
authors: ER
authors: Tamm
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005136:Eye Proteins / Q000378:metabolism*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D005902:Glaucoma, Open-Angle / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D014019:Tissue Donors; D014129:Trabecular Meshwork / Q000378:metabolism*; D000099179:Myocilin
chemical_list: D003598:Cytoskeletal Proteins; D005136:Eye Proteins; D006023:Glycoproteins; D000099179:Myocilin