OCULUS

Open angle glaucoma (OAG) is the second leading cause of world blindness. Treatments involving topically applied pressure-reducing medications or surgery targeting ocular drainage channels are effective, although significant complications exist. We propose to address the hypothesis that it is possible to develop a radical approach to management of intraocular pressure employing an AAV-mediated system for increasing the permeability of Schlemms canal endothelial cells (SCEC), based on published supportive data from this laboratory showing that RNAi-mediated down regulation of mRNA encoding components of tight junctions of neuronal vascular endothelia induces increased cell permeability, a process which has been used to validate a procedure for acute treatment of neuronal edema. While tight junctions of neuronal vascular endothelial cells have been extensively studied and comprise of a series of up to 30 protein components, less is known of the organization of adherence mechanisms of SCEC, although electron- and immunofluorescence microscopy show the presence of tight junctions. We propose a comprehensive analysis of tight junction protein expression in SCEC in vitro. In vivo studies will involve introduction of AAV vectors into the anterior chamber of the eye in rodent models of elevated IOP. The vectors will be designed to express shRNAs targeting a variety of tight junction transcripts expressed in SCEC using an inducible system. The effect of RNAi-mediated increase in the permeability of SCEC will be assessed using aqueous humour outflow measurement methods and we will also explore the utility of high resolution and diffusion-weighted MRI for this purpose, which may prove to be a simpler, non-invasive and clinically relevant method. This research will provide further fundamental insights into the mechanisms of ocular pressure maintenance and could provide benefit to those patients not responsive to conventional means of therapy.