Treatment with Neuropeptide alpha-Melanocyte Stimulating Hormone Suppresses Progression of Fuchs Dystrophy in a UV-induced Mouse Model

Abstract

Purpose : Fuchs Endothelial Corneal Dystrophy (FECD) is characterized by a progressive loss of corneal endothelial cells (CEnC) leading to corneal edema and vision loss. Our previous work has shown the cyto-protective effect of early treatment with the neuropeptide alpha-Melanocyte Stimulating Hormone (α-MSH) in preventing the development of Fuchs dystrophy in a murine model of UV-A induced FECD. This study aims to investigate the suppressive effect of α-MSH on CEnC loss after the development of endothelial changes implicated in FECD.

Methods : 8 week-old female C57BL/6 mice (n=8/group) were irradiated with UV-A (500J/cm²). 2 weeks post-irradiation, CEnC were imaged using in vivo confocal microscopy. Cell density, %hexagonality, & coefficient of variation (CV) were quantified using Konan’s CELLCHEK. Development of early stages of the Fuchs phenotype (CEnC loss and morphological changes) was noted, and α-MSH supplementation (1.67μg/g) was initiated in the treatment group and continued 3x/week for 10 weeks. At week 4, 8, and 12, CEnC were imaged and central corneal thickness (CCT) was measured via Optical Coherence Tomography. Cultured human CEnC were exposed to 150μM H₂O₂ and then incubated in medium containing 10 ^-6 M of α-MSH (treatment) vs. medium (control). Phosphorylated H2AX (γ-H2AX) staining was utilized to compared # of double stranded DNA breaks in treated vs. untreated groups.

Results : At 12 weeks post-irradiation, CEnC in the treated group compared to control had a significantly higher mean cell density (1252.4±83.3 vs. 1007±71.9, p<0.05), lower cell size variability (CV 44.7±2.6 vs. 57.5 ± 4.9, p<0.05) and higher % of cells retaining hexagonality (49.5±1.3 vs. 44.5±1.8, p<0.05). Corneal edema depicted by CCT was noted in untreated corneas starting at week 4, and progressively worsened. By week 12, CCT was significantly lower in the treated group compared to untreated (91.9±6.6 vs. 138.4 ±7.1, p=<0.001). In vitro, γ-H2AX staining was significantly lower in the group rescued with α-MSH compared to control (0.79±0.09 vs. 6.16±0.5 foci/cell, p<0.0001).

Conclusions : Treatment with α-MSH after the development of early UV-induced CEnC phenotypic changes, suppressed the progression and worsening of the FECD phenotype in this murine model. The preserved CEnC morphological and functional integrity maintained corneal thickness and prevented corneal decompensation.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.