title: Lack of type XVIII collagen results in anterior ocular defects.
abstract: Mice lacking type XVIII collagen have defects in the posterior part of the eye, including delayed regression of the hyaloid vasculature and poor outgrowth of the retinal vessels. We report here that these mice also have a fragile iris and develop atrophy of the ciliary body. The irises of Col18a1-/- mice can be seen to adhere to the lens and cornea. After the pupils begin to function, the double layer of epithelial cells separates at the apical cell contacts, leading to defoliation of its posterior pigment epithelial cell layer, and extracellular material begins to accumulate in the basement membrane zones of the iris. In contrast to the iris epithelia, where no clear signs of cellular atrophy were detected, the lack of type XVIII collagen resulted in atrophy of the pigmented epithelial cells of the ciliary body, and there were also ultrastructural abnormalities in the basement membrane zones. These changes did not lead to chronically elevated intraocular pressures, however. Our results indicate that type XVIII collagen is needed for the integrity of the epithelial basement membranes of the iris and the ciliary body and that its gene should therefore be taken into account as a new potential cause of anterior segment disorders in the eye.
authors.affiliation: Collagen Research Unit, Biocenter Oulu and Department of Medical Biochemistry and Molecular Biology, University of Oulu, Finland.
authors.forename: Ritva
authors.initials: R
authors.lastname: Ylikärppä
authors.forename: Lauri
authors.initials: L
authors.lastname: Eklund
authors.forename: Raija
authors.initials: R
authors.lastname: Sormunen
authors.forename: Antti I
authors.initials: AI
authors.lastname: Kontiola
authors.forename: Aino
authors.initials: A
authors.lastname: Utriainen
authors.forename: Marko
authors.initials: M
authors.lastname: Määttä
authors.forename: Naomi
authors.initials: N
authors.lastname: Fukai
authors.forename: Björn R
authors.initials: BR
authors.lastname: Olsen
authors.forename: Taina
authors.initials: T
authors.lastname: Pihlajaniemi
mesh_terms: D000818:Animals; D001485:Basement Membrane / Q000033:anatomy & histology; D002924:Ciliary Body / Q000002:abnormalities* / Q000033:anatomy & histology; D043170:Collagen Type XVIII / Q000235:genetics / Q000502:physiology*; D005123:Eye / Q000033:anatomy & histology; D007429:Intraocular Pressure; D007498:Iris / Q000002:abnormalities* / Q000033:anatomy & histology; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010857:Pigment Epithelium of Eye / Q000033:anatomy & histology
chemical_list: D043170:Collagen Type XVIII