The eye is 10 times more susceptible to exposure to vesicants than other organs. The aftermath of these
exposures and their impacts on human vision are easy to underestimate since many ocular symptoms may
manifest long after exposure. Thus, it has been documented that the survivors of a vesicant attack during the
Iraq–Iran War not only experienced corneal damage in the first 30 h after the attack but also manifested
diminished scotopic and photopic electroretinogram responses 40 years later. In addition, delayed symptoms in
these individuals also included central retinal vein occlusion and an increase of soluble VEGF-A in their tears.
Currently, there is no effective antidote to combat vesicant-induced ocular damage and vision loss in humans.
Therefore, our long-term goal is to generate effective medical countermeasures to mitigate the consequences of
such exposures. This goal will not be achievable unless we increase our molecular understanding of the
underlying mechanism responsible for the ocular damage and progressive ocular injuries caused by vesicant
exposure. Therefore, in this proposal, we analyze direct ocular exposure (DOE) to vesicants to identify the
molecular signaling driving the acute and chronic stages of corneal, vascular, and retinal pathobiology. Focusing
on the unfolded protein response (UPR)-TRIB3 downstream signaling, we hypothesize that, upon DOE, not only
the corneal tissue but also other ocular tissues, such as vascular and retinal tissues, are damaged, and
depending on the severity, vesicant exposure activates UPR-TRIB3 signaling in the cornea, which further
propagates the VEGF signal, causing blood vessel dysfunction and retinal injury. To dissect the mechanistic link
between direct ocular exposure and pathophysiology, we propose a diverse spectrum of step-by-step strategies
and a broad arsenal of tools. These tools include different animal models (mice and tree shrews), corneal and
retinal ex vivo tissue, corneal and retinal cultured cells, two different toxicants (lewisite and nitrogen mustard),
and genetic ablation of TRIB3 in the corneal, vascular, and retinal tissue to block the TRIB3-VEGF signal and
delay the onset of ocular injuries. The latter will be confirmed in experiments with vesicant-exposed animals
treated with a small-molecule inhibitor VEGF-Trap-Eye. Therefore, in Aim #1, we propose to investigate whether
DOE to vesicants activates the UPR-TRIB3-VEGF axis, acting as a molecular driver of corneal tissue injury. We
will demonstrate the molecular consequences of corneal-originated TRIB3-VEGF axis activation. In Aim #2, we
intend to determine whether secreted corneal TRIB3-mediated VEGF signal drives vascular pathogenesis by
assessing corneal neovascularization (NV) and retinal blood vessel disruption. In Aim #3, we plan to investigate
whether secreted cornea- and vascular-mediated VEGF drives the pathophysiology of retinal injury through the
activation of UPR-TRIB3. These studies will identify a novel and highly interesting molecular mechanism by
which the activated UPR-TRIB3-VEGF axis acts as a molecular driver of ocular tissue pathobiology and will
establish a groundwork for future mechanistic studies of ocular toxicity in exposed populations.