July 2019
Volume 60, Issue 9
Free
ARVO Annual Meeting Abstract  |   July 2019
Vitamin D enhances the autophagic lysosomal clearance in oxidatively stressed human corneal epithelial cells: A therapeutic intervention for keratoconus
Author Affiliations & Notes
  • Shivapriya Shivakumar
    GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, Karnataka, India
  • Rohit S
    Department of Cornea and Refractive Surgery, Narayana Nethralaya Post Graduate Institute of Ophthalmology,, Narayana Nethralaya Eye Hospital, Bangalore, India
  • Arkasubhra Ghosh
    GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, Karnataka, India
  • Nallathambi Jeyabalan
    GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, Karnataka, India
  • Footnotes
    Commercial Relationships   Shivapriya Shivakumar, None; Rohit S, None; Arkasubhra Ghosh, None; Nallathambi Jeyabalan, None
  • Footnotes
    Support  NONE
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 2819. doi:
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      Shivapriya Shivakumar, Rohit S, Arkasubhra Ghosh, Nallathambi Jeyabalan; Vitamin D enhances the autophagic lysosomal clearance in oxidatively stressed human corneal epithelial cells: A therapeutic intervention for keratoconus. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2819.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Oxidative stress is known to play a major role in the development of ocular surface diseases. Autophagy is a vital cellular mechanism, activated during oxidative stress. In Keratoconus (KC), dysregulated autophagy is associated with disease severity. Vitamin D receptor (VDR) is ubiquitous in nature and it is required for ocular health. Vitamin D3 (Vit D3) activates VDR and its deficiency is associated with ocular surface diseases like KC. Aim of this study is to understand the role of Vit D3 in regulating autophagosomal lysosomal pathway in KC and human corneal epithelial cells exposed to chronic oxidative damage

Methods : On approval of institutional ethics committee, informed consents were obtained from study subjects. 50 corneal epithelia were collected which includes 30 KC patients (Amsler Krumeich grades 1-3; 10/per grade) undergoing T-PRK or corneal crosslinking and 20 controls undergoing PRK. Quantitative PCR and western blotting were performed from across patient groups for measuring VDR levels. The in-vitro study, human corneal epithelial cells (HCE) exposed to chronic hyperoxic and normoxic conditions were assessed for autophagy lysosomal related markers and VDR expression through qPCR, WB, fluorescence staining

Results : KC epithelium showed significant reduction of (>2 fold; p<0.001) in expression level of VDR across disease grades compared to control. Ectatic cone epithelium of KC showed reduced levels of VDR compared to matched periphery in advanced stage. In addition, HCE cells exposed to chronic oxidative stress showed 50% reduction in the expression level of VDR (p<0.01) compared to normoxic cells. Vit D3 treatment elevated VDR levels to 1.5 fold higher in HCE cells exposed chronic oxidative stress. Vit D3 enhanced the synthesis of autophgosome (LC3) and lysosomes (LAMP1) in HCE cells under hyperoxia as observed by cyto ID and lysotracker staining and western blotting. Additionally, Vit D3 treatment also maintained the lysosomal pH and enzymatic activity in oxidatively damaged HCE cells

Conclusions : We found decreased epithelial expression of VDR across clinical grades of KC. In vitro data suggests that Vit D3 enhances VDR and activates autophagic lysosomal clearance in oxidatively damaged HCE cells. Therefore, regulation of VDR through Vit D3 supplementation could be an alternate therapeutic strategy for treating KC

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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