Abstract
Purpose :
Zika virus (ZIKV) infection causes severe ocular manifestations in neonates; however, the molecular mechanism behind ZIKV-induced ocular complications remains elusive. Based on our recent transcriptomics study, we hypothesize that ZIKV infection induces unfolded protein response (UPR) in ocular tissue. The UPR is a cellular adaptive response for restoring endoplasmic reticulum (ER) homeostasis in response to the presence of misfolded or unfolded proteins. Virus acquisition of host protein synthesis machinery during infection causes ER stress. In the current study, we investigated the role of ER stress in ZIKV ocular infection.
Methods :
Primary human trabecular meshwork cells (HTMC) and retinal pigmented epithelial cells (ARPE19) were infected with ZIKV (strain PRVABC59, PR-2015) in the presence and absence of ER stress inhibitors (4µ8c, GSK2606414, STF083010, and 4-Phenylbutyric Acid). The impact of ER stress modulation on viral replication and cell health was evaluated by measuring the activation/inhibition of ER stress sensors- ATF6, IRE1α, and PERK and their downstream effectors- XBP1s, ATF4, eif2α, CHOP, etc., alongside viral replication and cell death markers employing immunoblotting, immunofluorescence staining, and qPCR. For in vivo studies, WT and IFNAR1-/- mice were challenged with ZIKV, and modulation of ER stress was measured in different ocular tissues.
Results :
ZIKV infection predominantly activated IRE1α and PERK-mediated ER stress pathways in ARPE19 and HTMC cells as well as in the mouse anterior segment and retinal tissue. Moreover, the ATF6 pathway was transiently activated upon ZIKV infection. Pharmacological inhibition of ER stress pathways attenuated the ZIKV replication in ocular cells and promoted cell survival. ER stress inhibition invoked toned innate immune and antiviral responses in ARPE19 and HTMC cells and mouse ocular tissue.
Conclusions :
Our findings suggest that ER stress plays a critical role in ZIKV ocular pathogenesis, and pharmacological modulation of ER stress could be a potential strategy for averting ZIKV-associated ocular complications.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.