Reverse engineering glaucoma

• Main Author: Lester, Karen Leah
• Other Authors: Willoughby, Colin ; Sheridan, Carl ; Choudhary, Anshoo ; Hamill, Kevin
• Published: University of Liverpool 2018
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.755732

Primary open angle glaucoma (POAG) is a leading cause of irreversible blindness worldwide, and the only modifiable risk factor is intraocular pressure (IOP). Glaucoma is a complex disease with specific endophenotypes, and disease pathogenesis is likely to involve multiple pathways linking genetic and environmental interactions. Growth factors present in the aqueous humour in POAG increase outflow resistance and elevate IOP. TGF-β2 alters ECM production and turnover in the trabecular meshwork (TM) and has been shown in numerous studies to play a role in the pathogenesis of POAG. No current pharmacological interventions target the deleterious effects of TGF-β2 of the TM which produced elevated IOP. In addition to TGF-β another well characterised glaucoma stimulus is corticosteroids. Corticosteroids are used in ophthalmology to decrease inflammation and preserve ocular function. However side effects including cataract, enhanced infection, and glaucoma are associated with their use. Small, naturally occurring regulatory genes, micro RNAs (miRNAs), target many genes downstream of TGF-β2 and are expressed in response to corticosteroids. The current work set out to identify key differentially expressed genes by RNA-Seq in the human trabecular meshwork (TM) in response to two glaucoma stimuli; TGF-β2 and dexamethasone; and investigate the ability of miRNAs to manipulate gene expression within the TM to reduce pathological insults central to glaucoma. Investigating the influence of TGF-β2 on gene expression in primary human TM cells demonstrated that the majority of the significantly differentially expressed genes were involved in extracellular matrix remodelling and actin cytoskeletal re-organisation likely via the RhoA signalling pathway. The influence of dexamethasone on gene expression in primary human TM cells identified genes involved in extracellular matrix remodelling and genes required for glucocorticoid receptor nuclear translocation. Differentially expressed miRNAs in healthy and glaucomatous human TM cells were identified by a miRNA microarray. Manipulation of validated mRNA targets by identified miRNAs indicated a complex regulatory network and in vitro functional analyses further identified regulation of actin cytoskeleton remodelling via miRNA inhibition. The findings of this study indicate that TGF-β2 and dexamethasone have significant effects on extracellular matrix remodelling and actin cytoskeletal re-organisation in human TM cells. The RNA-Seq and miRNA array have identified potential novel therapeutic targets for glaucoma.