Caspase-14 expression impairs retinal pigment epithelium barrier function: potential role in diabetic macular edema

  • Biomed Res Int. 2014;2014:417986. doi: 10.1155/2014/417986.
Selina Beasley  1 ,  Mohamed El-Sherbiny  2 ,  Sylvia Megyerdi  3 ,  Sally El-Shafey  4 ,  Karishma Choksi  4 ,  Ismail Kaddour-Djebbar  5 ,  Nader Sheibani  6 ,  Stephen Hsu  4 ,  Mohamed Al-Shabrawey  7
Affiliations
  • 1. Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University (GRU), Augusta, GA 30912, USA ; Oral Biology/Anatomy, College of Dental Medicine, GRU, Augusta, GA 30912, USA ; Culver Vision Discovery Institute and Department of Ophthalmology, Medical College of Georgia, GRU, Augusta, GA 30912, USA.
  • 2. Oral Biology/Anatomy, College of Dental Medicine, GRU, Augusta, GA 30912, USA ; Culver Vision Discovery Institute and Department of Ophthalmology, Medical College of Georgia, GRU, Augusta, GA 30912, USA ; Department of Anatomy, Mansoura Faculty of Medicine, Mansoura University, Mansoura, Egypt.
  • 3. Oral Biology/Anatomy, College of Dental Medicine, GRU, Augusta, GA 30912, USA ; Culver Vision Discovery Institute and Department of Ophthalmology, Medical College of Georgia, GRU, Augusta, GA 30912, USA.
  • 4. Oral Biology/Anatomy, College of Dental Medicine, GRU, Augusta, GA 30912, USA.
  • 5. Department of Physiology, Medical College of Georgia, GRU and Charlie Norwood VA Medical Center, Augusta, GA 30912, USA.
  • 6. Departments of Ophthalmology and Visual Sciences and Biomedical Engineering, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
  • 7. Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University (GRU), Augusta, GA 30912, USA ; Oral Biology/Anatomy, College of Dental Medicine, GRU, Augusta, GA 30912, USA ; Culver Vision Discovery Institute and Department of Ophthalmology, Medical College of Georgia, GRU, Augusta, GA 30912, USA ; Department of Anatomy, Mansoura Faculty of Medicine, Mansoura University, Mansoura, Egypt.
PMID: 25121097 DOI: 10.1155/2014/417986
Abstract

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.