Abstract
The cornea is avascular, which makes it an excellent model to study matrix protein expression and tissue stiffness. The corneal epithelium adheres to the basement zone and the underlying stroma is composed of keratocytes and an extensive matrix of collagen and proteoglycans. Our goal was to examine changes in corneas of 8- and 15-week mice and compare them to 15-week pre-Type 2 diabetic obese mouse. Nanoindentation was performed on corneal epithelium in situ and then the epithelium was abraded, and the procedure repeated on the basement membrane and stroma. Confocal imaging was performed to examine the localization of proteins. Stiffness was found to be age and obesity dependent. Young’s modulus was greater in the epithelium from 15-week mice compared to 8-week mice. At 15 weeks, the epithelium of the control was significantly greater than that of the obese mice. There was a difference in the localization of Crb3 and PKCζ in the apical epithelium and a lack of lamellipodial extensions in the obese mouse. In the pre-Type 2 diabetic obese mouse there was a difference in the stiffness slope and after injury localization of fibronectin was negligible. These indicate that age and environmental changes incurred by diet alter the integrity of the tissue with age rendering it stiffer. The corneas from the pre-Type 2 diabetic obese mice were significantly softer and this may be a result of changes both in proteins on the apical surface indicating a lack of integrity and a decrease in fibronectin.
Highlights
One area of great interest is understanding if the changes that occur to tissues and cells with disease or age reflect physical changes
When epithelial cells migrate they generally move as a sheet of cells to heal a wound rather than discrete cells and we hypothesize that the sheet generates unique forces on the underlying basement membrane depending on the stiffness of the substrate [4]
Response to the basement membrane is critical as changes in the composition of the basement membrane have been shown to mediate cell signaling associated with cell adhesion and migration [6,7]
Summary
One area of great interest is understanding if the changes that occur to tissues and cells with disease or age reflect physical changes. The cornea provides a superb tissue to study changes in stiffness in epithelium, basement membrane proteins and stromal matrix proteins as it is accessible, and its properties can be readily examined. This tissue is constantly subjected to a wide range of mechanical stimuli. Investigators have demonstrated that the matrix proteins change in the basement membrane zone of diabetic corneas with a decrease in laminin and an increase in heparan sulfate proteoglycans [16]. There is little if any change in stiffness in the stroma in the 15-week DiO mice To understand these changes, we examined the polarity protein, Crumbs, that is associated with tight junctions in the epithelium. Together our results demonstrate that age and environment impact the integrity of the cornea
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
