June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
Aryl hydrocarbon receptor (AHR): potential link between autophagy and inflammation in retinal pigment epithelial (RPE) cells.
Author Affiliations & Notes
  • Mayur Choudhary
    Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
  • Goldis Malek
    Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
    Pathology, Duke University School of Medicine, Durham, North Carolina, United States
  • Footnotes
    Commercial Relationships   Mayur Choudhary, None; Goldis Malek, None
  • Footnotes
    Support  EY028160 (Goldis Malek)
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 3282. doi:
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      Mayur Choudhary, Goldis Malek; Aryl hydrocarbon receptor (AHR): potential link between autophagy and inflammation in retinal pigment epithelial (RPE) cells.. Invest. Ophthalmol. Vis. Sci. 2021;62(8):3282.

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

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Abstract

Purpose : Increasing evidence suggests an association between autophagy, and age-related degenerative disorders. AHR is a transcription factor mainly known for its role in toxin metabolism. Recently however, it has also been shown to regulate inflammation and autophagy. Aged Ahr-/- mice exhibit several phenotypic features of dry AMD including increased expression of inflammatory markers in the RPE/choroid, as shown by RNAseq and morphological flatmount analyses. Herein, we further investigated the role of AHR expression and function in regulating inflammation and autophagy in RPE cells.

Methods : In vivo, aged Ahr-/- and Ahr+/+ mice were used to (1) study inflammation in the sub-retinal space by staining RPE-choroid flatmounts for F4/80 (macrophages) and phalloidin (RPE cell borders); (2) generate a cytokine profile of the posterior retina; and (3) measure levels of autophagy proteins (LC3B, SQSTM1/p62, Beclin1, Atg5, Atg7) in the posterior retina. In vitro, human and mouse primary RPE cultures were used to study the effect of AHR knockdown and modulation of AHR activity (Agonists: n=4, Antagonists: n=2) on autophagy. Finally, we tested the therapeutic potential of modulating AHR activity (chronic/acute), on autophagy and inflammation in RPE cells exposed to oxidative insults.

Results : Ahr-/- mice displayed a significant upregulation of F4/80+ sub-retinal cells in aged mice as compared to Ahr+/+ mice (3.5-fold in 12-14 month old, 3-fold in 18-22 month old, n=4, p<0.04). RPE-choroid protein lysates exhibited significant upregulation of LC3B in 12-14 month old (2.5-fold) as well as 18-22 month old (2-fold) in Ahr-/- mice as compared to Ahr+/+ mice (n=4, p<0.05). Interestingly, RPE/choroid samples from a 12-14 month old cohort, showed significant downregulation of p62/SQSTM1 protein levels (2-fold, n=4, p<0.05). In vitro results, consistent with the in vivo findings, showed an induction of autophagosome formation in RPE cells as measured by LC3B II/ LC3B I ratio, with AHR knockdown (4.5-fold, n=3, p<0.05).

Conclusions : The absence of Ahr is associated with an increase in inflammation and autophagosome formation in the RPE-choroid milieu. These finding along with our previous reports of RPE cell dystrophy and accumulation of extracellular sub-RPE deposits in aged Ahr-/- mice, support the premise that targeting the AHR signaling pathway may improve RPE cellular turnover and health.

This is a 2021 ARVO Annual Meeting abstract.

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