Impact of MMP-9 in Closed Eye on Dry Eye Pathogenesis

Abstract

Dry eye disease is a common reason that people seek medical attention for their eyes. During sleep, the ocular surface becomes inflammatory to help maintain overall eye health. However, it is possible that the inflammation may be dysregulated and linked to the development of dry eye disease. Neutrophils are released as an immune response and secrete matrix metalloprotease-9 (MMP-9), which degrades the collagen of epithelial cells and further disrupts the tear film. MMP-9 activity can indicate inflammation, damage, and other ocular abnormalities. Normal and dry eye subjects were instructed to perform a saline eye wash immediately upon awakening to collect tear fluids from the closed eye environment. Performing this eye wash could potentially remove MMP-9 from the ocular surface and be effective in reducing dry eye symptoms. ELISAs were performed on these supernatants to measure the concentration and activity of pro- and active forms of MMP-9. These results were compared across all subjects before and after treatment to determine a relationship between symptoms and MMP-9 concentration. We found that in the normal and dry eye groups, the treatment reduced MMP-9 levels in the tear film. No significant difference in MMP-9 concentration was found between normal and dry eye subjects. These findings may implicate a saline eye wash as an effective method of alleviating dry eye symptoms.