June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Oxidative and nitrosyl stress combine to promote atrophy expansion in a rodent model of late, dry Age Related Macular Degeneration (AMD)
Author Affiliations & Notes
  • Natalie Pankova
    Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
    Translatum Medicus Inc, Ontario, Canada
  • Matthew Mina Reyad
    University of Toronto Scarborough, Toronto, Ontario, Canada
    Ophthalmology & Vision Sciences, University of Toronto, Toronto, Ontario, Canada
  • Rahul Joshi
    University of Toronto Scarborough, Toronto, Ontario, Canada
    Ophthalmology & Vision Sciences, University of Toronto, Toronto, Ontario, Canada
  • Hai Wang
    Ophthalmology & Vision Sciences, University of Toronto, Toronto, Ontario, Canada
    Department of Opthalmology, St Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
  • Xu Zhao
    Ophthalmology & Vision Sciences, University of Toronto, Toronto, Ontario, Canada
    Department of Opthalmology, St Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
  • Shelley R Boyd
    Ophthalmology & Vision Sciences, University of Toronto, Toronto, Ontario, Canada
    Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
  • Footnotes
    Commercial Relationships   Natalie Pankova Translatum Medicus Inc, Code C (Consultant/Contractor); Matthew Reyad None; Rahul Joshi None; Hai Wang None; Xu Zhao None; Shelley Boyd Translatum Medicus Inc, Code I (Personal Financial Interest), Translatum Medicus Inc, Code O (Owner), Translatum Medicus Inc, Code P (Patent)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 3897. doi:
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      Natalie Pankova, Matthew Mina Reyad, Rahul Joshi, Hai Wang, Xu Zhao, Shelley R Boyd; Oxidative and nitrosyl stress combine to promote atrophy expansion in a rodent model of late, dry Age Related Macular Degeneration (AMD). Invest. Ophthalmol. Vis. Sci. 2023;64(8):3897.

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

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Abstract

Purpose : Geographic atrophy (GA) is a leading cause of blindness, and though emerging therapies can slow GA expansion by up to 35%, this primary outcome measure is shared by few preclinical models. Increasing epidemiological, histologic, & metabolomic data suggest that both nitrosyl and oxidative stress correlate with advanced AMD. We thus hypothesized that pharmacological challenge with both stressors, in a two-pulse experiment, could induce atrophy expansion.

Methods : Assessed by in vivo cSLO imaging, adult male Sprague Dawley rats were challenged with high dose intravenous (iv) sodium iodate (NaIO3; 45mg/kg) to reliably generate full-fundus atrophy, or low dose NaIO3 (25-33mg/kg) to induce smaller areas of atrophy (<2/3 fundus). A low dose 1st pulse was then followed by a 2nd pulse of (i) NaIO3 alone (low or high), (ii) nitroglycerine alone (NTG; 2mg/kg/min x30 min), or (iii) high NaIO3+NTG. To address potential mechanisms, NaIO3+chloroquine (CQ; 21mg/kg/min x30 min), a known autophagy inhibitor, was used as the 2nd pulse; the influence of NTG on vasopermeability was assessed by fluorescein angiography (FA). Autophagy markers and nitrosyl modification of tissue protein and were assessed by immunohistochemistry (IHC). Viability of human hTERT-RPE1 cells was challenged by NaIO3+/- NTG in vitro.

Results : A 1st, low dose pulse of NaIO3 induced small areas of damage that did not expand over time (0/61 eyes). A 2nd pulse of low dose NaIO3, given 1 week after the 1st, also did not induce expansion, nor did a 2nd pulse of high dose NaIO3, given at 3 days, 1 week or 1 month (4/46, 9%). However, when high dose NaIO3+NTG were combined in the 2nd pulse, at 1 week, atrophy expansion occurred in 93% of eyes (26/28). NaIO3+CQ did not induce expansion (0/6). No vascular leakage that could increase NaIO3 delivery was observed, and no nitrotyrosine reactivity was seen in tissue. Beclin and LC3 IHC signal was low compared to no NaIO3 controls. Isolated RPE cells were exquisitely sensitive to combined NaIO3+NTG stress.

Conclusions : Combined nitrosyl & oxidative stress is toxic to RPE and induces atrophy expansion in the rat eye. Though the mechanism is yet to be defined, these data suggest a potential causal link between AMD progression and nitrates, an increasingly reported correlation. This model therefore may be useful in preclinical drug testing.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

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