Synergistically acting agonists and antagonists of G protein–coupled receptors prevent photoreceptor cell degeneration

Photoreceptor degeneration is the central event leading to visual impairment or blindness in most retinal diseases. However, the discovery of safe and effective therapeutic strategies conferring photoreceptor protection remains challenging. A systems pharmacology approach, synergistically targeting distinct cellular pathways could provide an effective strategy for evaluating, preventing or treating retinal dystrophies. Here this concept was investigated using a mouse model of light-induced retinal degeneration. We show that a combination of FDA-approved drugs acting on different G protein-coupled receptors in a synergistic manner could protect retinas against light-induced degeneration when each drug in the combination treatment was administered at a sub-therapeutic dose. Furthermore, transcriptome analyses demonstrated that such combined treatments also preserved patterns of retinal gene expression more characteristic of the normal retina than did single therapies at higher doses. The current study thus supports a new systems pharmacology approach that may extend to other complex neurodegenerative disorders in addition to retinal diseases. Overall design: Male and female Abca4-/-Rdh8-/- at the age of 4- to 6-weeks were used for the current study. All mice were housed and maintained in a 12 h light (=10 lux)/12 h dark cyclic environment in the Animal Resource Center at the School of Medicine, Case Western Reserve University (CWRU). Bright light-induced retinal damage was generated by exposing Abca4-/-Rdh8-/- mice to white light delivered at 10,000 lux (150 W spiral lamp, Commercial Electric) for 30 min. All indicated treatments were administered by intraperitoneal injection 30 min prior to bright light exposure and retinas collected one day later. Single compounds and their tested doses were: 2-Bromo-a-ergocryptine methanesulfonate salt (BRM), metoprolol tartrate (MTP), tamsulosin (TAM), and doxazosin (DOX). Combined treatments were: BRM, MTP and TAM (BMT), or MTP, DOX, and BRM (MDB). Processed data files (linked as series supplementary files): DE_combined.txt; Significant differential expression results from the combined pretreatment experiment. DE_mono.txt; Significant differential expression results from the mono pretreatment experiment. eXpress_counts_combined.txt; Quantitation output from eXpress of effective counts from the combined pretreatment experiment. eXpress_counts_mono.txt; Quantitation output from eXpress of effective counts from the mono pretreatment experiment. eXpress_fpkm_combined.txt; Quantitation output from eXpress of fpkm values from the combined pretreatment experiment. eXpress_fpkm_mono.txt; Quantitation output from eXpress of fpkm values from the mono pretreatment experiment. normalized_fpkm_combined.txt; TMM normalized fpkm values from the combined pretreatment experiment. normalized_fpkm_mono.txt; TMM normalized fpkm values from the mono pretreatment experiment.

30

Chen Y, Palczewska G, Masuho I, Gao S, Jin H, Dong Z, Gieser L, Brooks MJ, Kiser PD, Kern TS, Martemyanov KA, Swaroop A, Palczewski K