Molecular Mechanisms of corneal wound repair

Boston University Medical Campus, Boston MA

Investigators

Linked publications & trials

Abstract

Diabetes is one of the leading pathologies known to increase the risk of ocular surface pathology often displayed as impaired corneal wound healing. In addition, corneal surgeries (i.e. corneal transplantation, removal of corneal epithelium during vitrectomy, or refractive surgery) can present clinical challenges in diabetic patients. Wound healing requires coordination and communication between adjacent cells and the underlying substrate. Our goal is to determine if the dysregulation of spatial and temporal protein localization that we detected in diabetic corneas is an underlying reason for its wound healing pathology. In this study, we will use the high fat diet- induced obesity (DiO) rodent model, a natural model of pre-type II diabetes, as 95% of new diabetic cases each year are Type II. Our preliminary data demonstrated alterations in several markers of apical-basal polarity in corneal epithelium compared to age-matched normal diet controls. For wound healing to occur, adjacent epithelial cells and the cells in the underlying substrate must communicate and coordinate their responses. We speculate that pathologies, such as recurrent erosion, occur when there is improper regulation of apical-basal polarity proteins, resulting in incomplete wound closure and a persistent wounded state. Our preliminary data demonstrated that when cell migration is impeded there are distinct changes in cell shape at the wound edge and back from the leading edge. The intense localization of Pannexin 1 at the wound edge and along apical cells is lost and there was diffuse staining back from the wound edge of DiO corneal epithelium compared to controls. These include ZO-1, which is present along the apical margin of the corneal epithelium and at the interface between the basal and wing cells, and Pannexin-1, a channel protein. The data demonstrated a loss of the distinct punctate pattern of ZO-1 in the apical cells. Crumbs3, a protein in the tight junction complex, was no longer observed cortically and was found throughout the epithelium. These findings indicate that while the proteins are expressed, the signals needed to organize cell polarity before and after wounding are impaired. Furthermore, a published interactome on pannexin1, proposed its association with a number of cytoskeletal proteins that mediate tension between cells. The ATP released through pannexin 1 channels can activate purinoreceptors and in turn mediate regulation of focal adhesions. Defining changes in apical-basal polarity, the proteins that establish it, and the forces propagated between cells that alter the shape of the epithelium are important in advancing the understanding of wound repair. We hypothesize that alterations in polarity proteins will affect adherens and tight junctions that will change mechanical tension and overall tissue architecture that orchestrates corneal remodeling during wound repair. The specific aims that we will address are: 1. Does the change in localization of channel proteins with injury mediate cytoskeletal organization? and 2. Does wound closure require assembly of proteins in a specific apical basal polarity?