Probing the Role of Melanocortin Type 1 Receptor Agonists in Diverse Immunological Diseases

• Published in: Frontiers in pharmacology 2019-01, Vol.9, p.1535-1535
• Main Authors: Spana, Carl, Taylor, Andrew W, Yee, David G, Makhlina, Marie, Yang, Wei, Dodd, John
• Format: Article
• Language: English
• Subjects: alpha-melanocyte stimulating hormone; inflammatory bowel disease; melanocortin; melanocortin 1 receptor; Pharmacology; PL-8177; PL-8331
• ISSN: 1663-9812; 1663-9812
• DOI: 10.3389/fphar.2018.01535

The melanocortin α-melanocyte stimulating hormone (α-MSH), an endogenous peptide with high affinity for the melanocortin 1 receptor (MC1r), has demonstrated prevention and reversal of intestinal and ocular inflammation in animal models. Preclinical studies were performed to determine whether two MC1r receptor agonists, PL-8177 and PL-8331, exhibit actions and efficacy similar to α-MSH in preventing and reversing intestinal and ocular inflammation. Both PL-8177 and PL-8331 were assessed in a Eurofins LeadProfilingScreen selectivity panel including 72 assays. PL-8177 and PL-8331 were evaluated in an assay using human whole blood stimulated by lipopolysaccharide to determine inhibition of tumor necrosis factor alpha (TNF-α); for comparison, adrenocorticotropic hormone (ACTH) and α-MSH were used as positive controls. PL-8177, dosed at 0.5, 1.5, and 5.0 μg, was assessed in a cannulated rat model of dinitrobenzene sulfonic acid (DNBS)-induced bowel inflammation versus vehicle and oral sulfasalazine. PL-8177 was also dosed at 0.3 mg/kg/mouse injected intraperitoneally versus untreated controls and α-MSH treatment in mice with experimental autoimmune uveitis (EAU). PL-8331 at 3 doses, 3 times daily, was evaluated in a murine model of scopolamine-induced dry eye disease (SiccaSystem model), versus twice-daily Restasis and Xiidra . Both PL-8177 and PL-8331 demonstrated no significant activity at the 1 μm concentration in any of the 72 assays. PL-8177 and PL-8331 inhibited lipopolysaccharide-induced TNF-α to a similar degree as ACTH and α-MSH. In the DNBS rat model of bowel inflammation, PL-8177 was significantly superior to untreated controls at all 3 doses ( < 0.05) in reducing bowel inflammation parameters, with effects similar to sulfasalazine. In the murine EAU model, PL-8177 significantly reduced retinal inflammation scores versus untreated controls ( = 0.0001) over 3-5 weeks, and to a similar degree as α-MSH. In the murine scopolamine-induced model of dry eye disease, PL-8331 reduced corneal fluorescein staining scores at all doses, significantly ( = 0.02) for the highest dose (1 × 10 mg⋅mL ), and similarly to Restasis ; Xiidra demonstrated no effect. The MC1r receptor agonists PL-8177 and PL-8331 exhibited actions similar to those of α-MSH in preventing and reversing intestinal and ocular inflammation in preclinical disease models.