# Mechanisms of Sensitization in High Risk Corneal Grafts

> **NIH NIH R01** · SCHEPENS EYE RESEARCH INSTITUTE · 2020 · $556,228

## Abstract

This is a competitive renewal application to further characterize the molecular and cellular facets of host
immunity in high-risk corneal transplants, performed in inflamed host beds and distinguished by their
rapid rejection. The goal of our grant, which has been supported since 2000, is to gain new insights into the
mechanisms that distinguish high-risk vs. low-risk transplant immunity. Our work has identified Foxp3hi
regulatory T cell (Treg) function as being critical for allotolerance and graft survival. Our overarching
hypothesis is that the high-risk graft is characterized by a microenvironment which abrogates the
tolerogenic potential of Tregs, rendering them incapable of protecting the allograft against immune-
mediated attack. This is supported by our data from transgenic mice demonstrating that in high-risk grafted
hosts some Tregs lose Foxp3 expression and convert into `exTreg' that express interferon-gamma (IFNγ),
an inflammatory cytokine which can exert damage on graft tissue. We thus propose to pursue the following
three specific aims: In Aim 1, we will determine the function of Tregs in protecting graft endothelial cells
against effector T cell-mediated (Aim 1A) and inflammatory cytokine-mediated (Aim 1B) attack. In Aim 2 we
plan to explore the function of different Treg phenotypes in regulating corneal angiogenesis, an entirely
novel area. Surprisingly, we have found that Foxp3-/lo Tregs, which have limited immunosuppressive
function, are potently anti-angiogenic. We will quantify the expression of different VEGF species and the
anti-angiogenic cytokine IFNγ by Tregs derived from low-risk and high-risk grafted hosts, hypothesizing that
a high IFNγ/VEGF ratio determines Treg angiostatic function. In Aim 3 we test the hypothesis that exTregs
not only have defective immunoregulatory function, but actually effect graft rejection, a wholly novel
concept. In Aim 3A we will determine the capacity of exTreg to induce graft loss, and in Aim 3B we will
determine the cytokine cues that induce Treg conversion to exTregs, devising strategies for preventing this
conversion and thus promoting graft tolerance. Our study design relies on using the core expertise of our
laboratory along with use of well-characterized mouse models of corneal transplantation in conjunction with
in vitro immunological and cell proliferation assays and use of a double transgenic mouse that permits us to
monitor the differentiation of Tregs to exTregs. The overall health relevance of this research is that corneal
grafting represents the number one form of transplantation performed in the United States. However, while
most high-risk corneal transplant patients rapidly reject their grafts, there has been no significant change in
the management of high-risk transplants for decades. Thus, the long-term objective of our project is to use
data derived from our studies to develop new strategies to promote graft acceptance without the use of
systemic immunosuppressive regimens ...

## Key facts

- **NIH application ID:** 9997934
- **Project number:** 5R01EY012963-21
- **Recipient organization:** SCHEPENS EYE RESEARCH INSTITUTE
- **Principal Investigator:** Reza Dana
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $556,228
- **Award type:** 5
- **Project period:** 2000-08-01 → 2021-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9997934

## Citation

> US National Institutes of Health, RePORTER application 9997934, Mechanisms of Sensitization in High Risk Corneal Grafts (5R01EY012963-21). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9997934. Licensed CC0.

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