Alpha-Melanocyte-Stimulating Hormone Maintains Retinal Homeostasis after Ischemia/Reperfusion

Abstract

Augmenting the natural melanocortin pathway in mouse eyes with uveitis or diabetes protects the retinas from degeneration. The retinal cells are protected from oxidative and apoptotic signals of death. Therefore, we investigated the effects of a therapeutic application of the melanocortin alpha-melanocyte-stimulating hormone (α-MSH) on an ischemia and reperfusion (I/R) model of retinal degenerative disease. Eyes were subjected to an I/R procedure and were treated with α-MSH. Retinal sections were histopathologically scored. Also, the retinal sections were immunostained for viable ganglion cells, activated Muller cells, microglial cells, and apoptosis. The I/R caused retinal deformation and ganglion cell loss that was significantly reduced in I/R eyes treated with α-MSH. While α-MSH treatment marginally reduced the number of GFAP-positive Muller cells, it significantly suppressed the density of Iba1-positive microglial cells in the I/R retinas. Within one hour after I/R, there was apoptosis in the ganglion cell layer, and by 48 h, there was apoptosis in all layers of the neuroretina. The α-MSH treatment significantly reduced and delayed the onset of apoptosis in the retinas of I/R eyes. The results demonstrate that therapeutically augmenting the melanocortin pathways preserves retinal structure and cell survival in eyes with progressive neuroretinal degenerative disease.

Immunopeptides: immunomodulatory strategies and prospects for ocular immunity applications

“…The immune imbalance of the eye brings great trouble to treating eye diseases (such as dry eye, uveitis, microbial infections, and tumors). As the blood-retina barrier (BRB) causes the immune privileges of the ocular, ocular surface ( 1 , 2 ), the central nervous system, and retina ( 3 , 4 ) secrete peptides and cytokines like TGF-β2 to regulate resident cells, resist pathogen invasion, and maintain ocular immune microenvironment ( 5 – 7 ). Since peptides maintain the immune microenvironment with diverse immune effects, understanding the pathogenesis of immune peptides in eye diseases is essential for developing effective treatments.…”