Survey of Dopamine Receptor D2 Antagonists as Retinal Antifibrotics.

Purpose: To evaluate the potency and efficacy of a library of dopamine receptor D2 (D2R) antagonists in the mitigation of fibrotic activation in retinal pigment epithelial (RPE) cells. Methods: ARPE-19 cells were cultured and treated with methotrexate or 27 district D2R antagonists using a fibronectin deposition assay. The most potent compounds were then further assessed in assays measuring cellular proliferation, cellular migration, and profibrotic gene expression. Results: The previously established antifibrotic D2R antagonist loxapine exerted a robust and dose-dependent inhibition of fibronectin deposition, whereas methotrexate exerted minimal inhibition. The most potent D2R antagonist identified, fluphenazine, effectively blocked in vitro models of fibrosis at 300-1,000 nM concentrations. Conclusions: Here we found multiple FDA-approved D2R antagonists that potently block RPE cell fibrogenesis. These findings further support the potential of D2R antagonism as a potential therapeutic for retinal fibrotic disease.

Serum-derived extracellular vesicles for the treatment of severe ocular surface disease.

PURPOSE: Autologous serum is widely used for the treatment of severe ocular surface disease with mixed efficacy. Extracellular vesicles (EVs) are small membrane bound structures present in all body fluids, including serum. This study compared the proteomic, metabolomic, and inflammatory cytokine composition of serum-derived EVs (SDEVs) to that of the soluble free protein fraction and the subsequent capacity of SDEVs to induce corneal epithelial cell migration and inflammation. METHODS: SDEVs were isolated from human serum using size exclusion chromatography. SDEVs were analyzed using nanoparticle tracking analysis, transmission electron microscopy, and western blotting. The effects of SDEVs on corneal epithelial cell migration were tested using a standard scratch assay. Inflammatory cytokines in SDEVs and the free protein fraction were quantified using a microarray. A mutli-omics approach was further used to define SDEV cargo. The ability of SDEVs to modulate inflammation in corneal epithelial cells was quantified using ELISAs. RESULTS: Western blot and TEM confirmed the presence of SDEVs. Proinflammatory cytokines, along with complement proteins and TGF-ß, were decreased in SDEVs compared to serum. Metabolites present in SDEVs were mostly involved in amino acid biosynthesis, the TCA cycle and oxidative phosphorylation. SDEVs exhibited pro-migratory effects similar to serum however, SDEVs did not induce secretion of IL-6 or IL-8. CONCLUSIONS: SDEVs exhibit reduced levels of pro-inflammatory cytokines while retaining the beneficial wound healing properties of serum. Unlike serum, SDEVs do not induce inflammation. SDEVs may represent an alternative option for patients with severe ocular surface disease where traditional autologous serum has failed.