Caspase-14 Expression Impairs Retinal Pigment Epithelium Barrier Function : Potential Role in Diabetic Macular Edema

• Published in: BioMed research international 2014-01, Vol.2014 (2014), p.1-11
• Main Authors: Beasley, Selina, El-Sherbiny, Mohamed, Megyerdi, Sylvia, El-Shafey, Sally, Choksi, Karishma, Kaddour-Djebbar, Ismail, Sheibani, Nader, Hsu, Stephen, al-Shabrawey, Mohamed
• Format: Article
• Language: English
• Subjects: Apoptosis; Apoptosis - drug effects; Biomedical research; Caspase 14 - metabolism; Cell Line; Colleges & universities; Dextrans - metabolism; Diabetic retinopathy; Diabetic Retinopathy - enzymology; Diabetic Retinopathy - pathology; Fluorescein-5-isothiocyanate - analogs & derivatives; Fluorescein-5-isothiocyanate - metabolism; Fluorescent Antibody Technique; Gene Knockdown Techniques; Glucose - pharmacology; Humans; Macular degeneration; Macular Edema - enzymology; Macular Edema - pathology; Models, Biological; Permeability - drug effects; Phagocytosis - drug effects; Retina; Retinal Pigment Epithelium - drug effects; Retinal Pigment Epithelium - enzymology; Retinal Pigment Epithelium - pathology; Risk factors
• ISSN: 2314-6133; 2314-6141
• DOI: 10.1155/2014/417986

We recently showed that caspase-14 is a novel molecule in retina with potential role in accelerated vascular cell death during diabetic retinopathy (DR). Here, we evaluated whether caspase-14 is implicated in retinal pigment epithelial cells (RPE) dysfunction under hyperglycemia. The impact of high glucose (HG, 30 mM D-glucose) on caspase-14 expression in human RPE (ARPE-19) cells was tested, which showed significant increase in caspase-14 expression compared with normal glucose (5 mM D-glucose + 25 mM L-glucose). We also evaluated the impact of modulating caspase-14 expression on RPE cells barrier function, phagocytosis, and activation of other caspases using ARPE-19 cells transfected with caspase-14 plasmid or caspase-14 siRNA. We used FITC-dextran flux assay and electric cell substrate impedance sensing (ECIS) to test the changes in RPE cell barrier function. Similar to HG, caspase-14 expression in ARPE-19 cells increased FITC-dextran leakage through the confluent monolayer and decreased the transcellular electrical resistance (TER). These effects of HG were prevented by caspase-14 knockdown. Furthermore, caspase-14 knockdown prevented the HG-induced activation of caspase-1 and caspase-9, the only activated caspases by HG. Phagocytic activity was unaffected by caspase-14 expression. Our results suggest that caspase-14 contributes to RPE cell barrier disruption under hyperglycemic conditions and thus plays a role in the development of diabetic macular edema.