title: The retinal pigment epithelium: something more than a constituent of the blood-retinal barrier--implications for the pathogenesis of diabetic retinopathy.
abstract: The retinal pigment epithelium (RPE) is an specialized epithelium lying in the interface between the neural retina and the choriocapillaris where it forms the outer blood-retinal barrier (BRB). The main functions of the RPE are the following: (1) transport of nutrients, ions, and water, (2) absorption of light and protection against photooxidation, (3) reisomerization of all-trans-retinal into 11-cis-retinal, which is crucial for the visual cycle, (4) phagocytosis of shed photoreceptor membranes, and (5) secretion of essential factors for the structural integrity of the retina. An overview of these functions will be given. Most of the research on the physiopathology of diabetic retinopathy has been focused on the impairment of the neuroretina and the breakdown of the inner BRB. By contrast, the effects of diabetes on the RPE and in particular on its secretory activity have received less attention. In this regard, new therapeutic strategies addressed to modulating RPE impairment are warranted.
authors.affiliation: CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III (ISCIII), Unitat de Diabetis i Metabolisme, Institut de Recerca Hospital Universitari Vall d'Hebron, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain. rsimo@ir.vhebron.net
authors.forename: Rafael
authors.initials: R
authors.lastname: Simó
authors.forename: Marta
authors.initials: M
authors.lastname: Villarroel
authors.forename: Lídia
authors.initials: L
authors.lastname: Corraliza
authors.forename: Cristina
authors.initials: C
authors.lastname: Hernández
authors.forename: Marta
authors.initials: M
authors.lastname: Garcia-Ramírez
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001813:Blood-Retinal Barrier / Q000502:physiology*; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D006801:Humans; D007477:Ions; D008027:Light; D008954:Models, Biological; D018384:Oxidative Stress; D010100:Oxygen / Q000737:chemistry; D010587:Phagocytosis; D010777:Photochemistry / Q000379:methods; D055213:Retinal Pigment Epithelium / Q000378:metabolism*; D012172:Retinaldehyde / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D000975:Antioxidants; D007477:Ions; D014867:Water; D012172:Retinaldehyde; D010100:Oxygen