The role of extracellular vesicles in keratoconus pathogenesis

PROJECT SUMMARY/ABSTRACT Keratoconus is a chronic, lifelong corneal dystrophy and affects approximately 1:400 people worldwide, including both males and females. Treating patients with advanced keratoconus has always been a challenge. Corneal transplantation remains the gold standard for treatment, however, significant risk of postoperative complications exist. Presently, keratoconus is diagnosed with specialized equipment and tests such as slit-lamp and Pentacam®. Early diagnosis, where irregular astigmatism can complicate things, is critical for the management of keratoconus. To-date, there are no biomarker tests which has consequently driven demand for novel approaches to assist in the diagnosis, management and/or treatment of keratoconus. Extracellular vesicles (EVs) are lipid bilayer-delimited particles released by cells, which may provide a real-time snapshot of the entire cell/tissue/organ in a non-invasive way. EVs can regulate physiological processes and contain components including proteins, miRNAs, DNA fragments, non-coding RNAs and lipids. Therefore, EVs hold promise for the discovery of future biomarkers. In the context of corneal diseases/dystrophies, tear fluid and tear EVs (tEVs) are the best candidate for biomarker investigations. Surprisingly, very few studies have been reported (only Dry eye and Sjogren’s syndrome) investigating tEVs. Our preliminary data provides strong evidence for the existence of tEVs in keratoconus patients that are phenotypically different from their healthy counterparts. The proposed clinical studies aim to unravel the role of tEVs in keratoconus pathobiology and discover relevant biomarkers associated with age, sex, and disease severity. During our preliminary studies, we have recruited a small cohort of healthy and keratoconus patients, and have put together a strong group of clinicians/collection sites that will assist us with sample collection during the proposed period. Our data suggests significant phenotypic differences in the tEVs derived from keratoconus patients, compared to healthy controls. We, therefore, propose an integrated multi-faceted “fingerprint” approach that will include tEV physical characterization, proteomics, and miRNA profiling. We believe that our strategy can shed light on future directions in this field for keratoconus diagnosis, management, and even treatment. Relevance to Public Health – KC is a major clinical problem resulting in visual impairment worldwide. The long- term implications of our study are important for KC patients since it could establish novel treatment modalities. Ultimately, the ability to effectively, and safely, manage/treat all KC patients, is vital. The proposed work is novel, translational, clinically relevant, and in line with NEI’s goals and research priorities to understand KC and develop novel treatment options to reduce the burden of the disorder worldwide.