OCX063, a novel small molecule drug, is protective against inflammatory, fibrotic and angiogenic phenotypes in retinal cultures

Abstract

Purpose : Retinal neurodegenerative diseases like diabetic retinopathy (DR), diabetic macular edema (DME) and age-related macular degeneration (AMD) are associated with dysregulated retinal inflammation, leading to aberrant angiogenesis and fibrosis. The impact of retinal acidosis in retinal pathology has recently been documented in multiple studies, highlighting pH as an important metabolic parameter. We previously showed that the small molecule drug OCX063 is orally active and has anti-inflammatory/anti-fibrotic effects, using in vivo DR and AMD models, and in vitro retinal microglia and Muller cell cultures. Here, we further explored the protective effects of OCX063 in retinal cultures in acidotic conditions.

Methods : Immortalized human retinal microvascular endothelial cells (HRMEC) and the retinal pigment epithelia cell line ARPE19 were used to investigate the efficacy of OCX063 in inhibiting angiogenesis, cell migration and fibrosis. Cells were induced with acidic pH 6.8 or physiological pH 7.6 medium, with or without OCX063. HRMEC were then analyzed for cell migration and angiogenesis via wound healing and tube formation assays, while ARPE19 cells were analyzed for inflammatory or fibrotic markers via RT-qPCR. The expression of phosphorylated p38 (p-p38) and JNK (p-JNK) was also measured via ELISA.

Results : pH 6.8 increased the migration and angiogenic potential of HRMEC, as cells were more motile and formed more loops compared to pH 7.6. Both responses were decreased by OCX063 at concentrations as low as 10μM (p<0.001) for migration and 1μM (p<0.01) for angiogenesis. pH 6.8 induced a fibrotic phenotype in ARPE19 cells by elevating the gene expression of fibronectin (p<0.001), α smooth muscle actin (p<0.01) and tumour growth factor β (p<0.001) over 2 folds compared to pH 7.6, which was decreased by 100μM OCX063 (all p<0.001). We also observed a corresponding increase in p-p38 and p-JNK at pH 6.8 in ARPE19 cells, which was decreased by 10μM OCX063 (p<0.001), suggesting their involvement in the anti-fibrotic properties of OCX063.

Conclusions : OCX063 prevents retinal inflammation, vascular pathology and fibrosis in various cultures of retinal cells, highlighting its multifactorial effects and potential for treating proliferative retinal diseases. OCX063 is expected to begin a Phase II clinical trial for DR/AMD in 2020.

This is a 2020 ARVO Annual Meeting abstract.