Therapeutic Effects of Stimulating the Melanocortin Pathway in Regulating Ocular Inflammation and Cell Death

Abstract

Alpha-melanocyte-stimulating hormone (α-MSH) and its binding receptors (the melanocortin receptors) play important roles in maintaining ocular tissue integrity and immune homeostasis. Particularly extensive studies have demonstrated the biological functions of α-MSH in both immunoregulation and cyto-protection. This review summarizes the current knowledge of both the physiological and pathological roles of α-MSH and its receptors in the eye. We focus on recent developments in the biology of α-MSH and the relevant clinical implications in treating ocular diseases.

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

“…Immune cells, when treated with α-MSH, after being stimulated by factors that promote inflammation, produce anti-inflammatory cytokines, suppress inflammation, and mediate immune tolerance [15]. Besides the suppression of inflammation, α-MSH rescues cells from apoptosis [14,[16][17][18][19][20]. Diabetic mice and rats treated with α-MSH or melanocortin receptor agonists have suppressed pathology and cytokines of diabetic retinopathy, including the retention of viable photoreceptors and ganglion cells [20][21][22][23][24].…”

“…Besides the suppression of inflammation, α-MSH rescues cells from apoptosis [14,[16][17][18][19][20]. Diabetic mice and rats treated with α-MSH or melanocortin receptor agonists have suppressed pathology and cytokines of diabetic retinopathy, including the retention of viable photoreceptors and ganglion cells [20][21][22][23][24]. In addition, mice with central vein occlusions survive longer with reduced stroke and retinal pathology following α-MSH treatment [25].…”

Melanocortin Derivatives Induced Vascularization and Neuroglial Proliferation in the Rat Brain under Conditions of Cerebral Ischemia

“…These agents should demonstrate high efficacy, clear specificity, low immunogenicity, biocompatibility, gentle action, and absence of adverse effects [ 13 , 14 , 15 ]. In recent years, there has been active development of melanocortin-based drugs [ 16 , 17 ]. Melanocortins are a large family of neuropeptides that originate from a common precursor, the molecule called proopiomelanocortin.…”