Plant-derived angiogenin fusion protein’s cytoprotective effect on trabecular meshwork damage induced by Benzalkonium chloride in mice

BACKGROUND: Benzalkonium chloride (BAK), commonly used in glaucoma treatment, is an eye drop preservative with dose-dependent toxicity. Previous studies have observed the multi-functional benefits of angiogenin (ANG) against glaucoma. In our study, we evaluated ANG’s cytoprotective effect on the trabecular meshwork (TM) damage induced by BAK. Additionally, we developed a plant-derived ANG fusion protein and evaluated its effect on TM structure and function. METHODS: We synthesized plant-derived ANG (ANG-FcK) by fuzing immunoglobulin G’s Fc region and KDEL to conventional recombinant human ANG (Rh-ANG) purified from transgenic tobacco plants. We established a mouse model using BAK to look for degenerative changes in the TM, and to evaluate the protective effects of ANG-FcK and Rh-ANG. Intraocular pressure (IOP) was measured for 4 weeks and ultrastructural changes, deposition of fluorescent microbeads, type I and IV collagen, fibronectin, laminin and α-SMA expression were analyzed after the mice were euthanized. RESULTS: TM structural and functional degeneration were induced by 0.1% BAK instillation in mice. ANG co-treatment preserved TM outflow function, which we measured using IOP and a microbead tracer. ANG prevented phenotypic and ultrastructure changes, and that protective effect might be related to the anti-fibrosis mechanism. We observed a similar cytoprotective effect in the BAK-induced degenerative TM mouse model, suggesting that plant-derived ANG-FcK could be a promising glaucoma treatment.