Glaucoma is an optic neuropathy in which the primary risk factor is elevated intraocular pressure (IOP). Dysregulation of conventional outflow homeostasis results in elevated IOP. Key elements of outflow homeostasis are the turnover of extracellular matrix (ECM), which also determines preferential flow passageways through the tissue. In fact, there is recent evidence of differential ECM gene expression between regions of low and high flow in the trabecular meshwork (TM). In cancer, dysregulation of ECM homeostasis has been demonstrated to involve extracellular nanovesicles, known as exosomes. Exosome release is tightly regulated, and they are differentiated from other nanovesicles based on their size, cell type-specific function and cargo. Amongst others, their functions include waste management, cell-cell signaling and ECM turnover. As a result, we hypothesize that exosomes released from TM cells play a role in opsonizing ECM in the outflow pathway, contributing to segmental flow, and altered ECM homeostasis in glaucoma. This study aims to investigate the role of exosomes in regulating ECM by human TM cells and in TM tissues. During the mentored phase, I will first examine the effect of mechanical stretch on exosomes released from primary human TM cells and create a comprehensive profile of exosomes released from TM explants, specifically profiling regions of low and high flow. During the independent phase, I will examine how IOP effects exosome release and regulation in the conventional outflow pathway in terms of segmental flow before examining how exosomes may be used as a platform to ameliorate the dysfunctional ECM homeostasis in glaucoma. As outcomes of this research we expect to (i) identify a role for exosomes in segmental flow (ii) determine the effect of IOP on exosome release and function (iii) identify ECM targets for exosome regulation and, (iv) ascertain if exosomes can be used to normalize ECM homeostasis.
Extracellular matrix homeostasis and its dysregulation that occurs in the trabecular meshwork tissues of glaucomatous eyes is complicated, and an area of intense research. The role of actively released exosomes in these processes is unknown. Due to the natural flow patterns of aqueous humor through the trabecular meshwork tissues, exosomes represent ideal platforms to participate in conventional outflow regulation.
