title: Hypoxia preconditioning protects corneal stromal cells against induced apoptosis.
abstract: The purpose of this study, was to determine whether hypoxia preconditioning can protect corneal stromal cells from UV stress and cytokine mediated apoptosis. Two models were implemented. First, primary cultured bovine corneal fibroblasts were preconditioned with 0.5-1.5% O2 for 4 hr and stressed with UV-irradiation or stimulation of Fas receptor. Second, bovine eyes were preconditioned with 0.5% O2 for 4 hr and stressed by epithelial scraping to induce anterior keratocyte apoptosis. Cell fate was analyzed at 4 hr after stress using quantitative TUNEL or condensed nuclei assays. Cell apoptotic rates in hypoxia preconditioned groups were significantly lower (50-80%) than that of normoxia control groups. Hypoxia prevented the degradation of the transcription factor HIF-1alpha. CoCl2 (100-200 microM), a chemical inducer of HIF-1alpha, also produced strong protection against UV and Fas induced apoptosis. Moreover, hypoxia preconditioned media protected cells against UV-induced apoptosis. These findings demonstrate that hypoxia preconditioning has a generalized protective effect against stromal fibroblast and keratocyte apoptosis and suggest that HIF-1alpha mediated expression and secretion of protective factors is involved.
authors.affiliation: School of Optometry, Indiana University, 800 East Atwater Avenue, Bloomington, IN 47405, USA.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Xing
authors.forename: Xingcai
authors.initials: X
authors.lastname: Sun
authors.forename: Jinhua
authors.initials: J
authors.lastname: Li
authors.forename: Miao
authors.initials: M
authors.lastname: Cui
authors.forename: Kah
authors.initials: K
authors.lastname: Tan-Allen
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Bonanno
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology* / Q000528:radiation effects; D015153:Blotting, Western; D002417:Cattle; D015687:Cell Hypoxia / Q000502:physiology*; D002478:Cells, Cultured; D003315:Cornea / Q000473:pathology* / Q000528:radiation effects; D017077:Culture Media, Conditioned; D053222:Fas Ligand Protein; D005347:Fibroblasts / Q000473:pathology / Q000528:radiation effects; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology; D020287:In Situ Nick-End Labeling; D019194:Ischemic Preconditioning; D008562:Membrane Glycoproteins / Q000502:physiology; D017154:Stromal Cells / Q000473:pathology* / Q000528:radiation effects; D048069:Tumor Necrosis Factors / Q000502:physiology; D014466:Ultraviolet Rays; D019014:fas Receptor / Q000502:physiology
chemical_list: D017077:Culture Media, Conditioned; D053222:Fas Ligand Protein; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008562:Membrane Glycoproteins; D048069:Tumor Necrosis Factors; D019014:fas Receptor