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Updated: Aug 6, 2026

Induction of Ocular Surface Inflammation and Collection of Involved Tissues
Published on: August 4, 2022
Melanocortin 5 receptor and ocular immunity
A W Taylor1, N Kitaichi, D Biros
1Schepens Eye Research Institute and the Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA. awtaylor@vision.eri.harvard.edu
Melanocortin 5 receptor (MC5r) expression is crucial for protecting the retina from autoimmune inflammation and inducing regulatory T cells. MC5r deficiency leads to severe retinal damage and impaired immune responses during experimental autoimmune uveoretinitis.
Area of Science:
- Ophthalmology
- Immunology
- Neuroscience
Background:
- The nervous system maintains ocular immune privilege through alpha-melanocyte stimulating hormone (alpha-MSH).
- Alpha-MSH, via the melanocortin 5 receptor (MC5r), induces regulatory T cells (Tregs) to suppress autoimmune disease.
- The role of MC5r in ocular immunity and Treg induction post-autoimmune inflammation is not fully understood.
Purpose of the Study:
- To investigate the role of MC5r in ocular immunity.
- To determine if MC5r is involved in the natural induction of regulatory T cells following experimental autoimmune uveoretinitis (EAU).
Main Methods:
- Comparison of EAU development and resolution in wild-type and MC5r-/- mice.
- Assessment of retinal damage, immune cell populations (Tregs), and immune memory responses.
- Localization of MC5r expression in retinal tissues.
Main Results:
- MC5r-/- mice exhibited severe retinal damage during EAU compared to wild-type mice.
- MC5r deficiency prevented the emergence of ocular autoantigen-specific regulatory immunity in the spleen.
- MC5r expression was found in retinal pigment epithelial cells and neural layers of healthy retinas.
- Retinal protection and induction of ocular autoantigen-responsive Tregs in the spleen post-EAU require MC5r expression.
Conclusions:
- MC5r plays a critical role in protecting the retina from inflammatory damage during EAU.
- MC5r is essential for inducing antigen-specific regulatory T cell responses in the spleen after EAU.
- While ocular recovery from EAU was not MC5r-dependent, retinal protection and Treg induction are.
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