Abstract
Purpose :
Interactions between epithelial cells and the surrounding stroma are centerpiece to tissue repair during corneal wound healing. One critical factor influencing this process is the maintenance of a proteolytic microenvironment. Here we evaluated the role of galectin-3 in promoting the expression of matrix metalloproteinases (MMPs) during heterotypic cell-cell interactions.
Methods :
Heterotypic cell-cell interactions between corneal epithelial cells and fibroblasts were assessed using time-lapse video microscopy. MMP9 expression was analyzed using a promoter-reporter epithelial cell line, qPCR and gel zymography. The contribution of galectin-3 to heterotypic cell-cell interactions was determined using full-length recombinant human galectin-3 and siRNA. Paracrine signals were identified using a real-time PCR inflammatory array. IL1β was analyzed by ELISA and abrogated using siRNA. Two animal models of corneal injury with or without the basement membrane were used in wild-type and galectin-3 null mice.
Results :
Direct contact of single cell fibroblast with the epithelial sheet was sufficient to promote the rapid and simultaneous activation of the MMP9 promoter in immediately adjacent clusters of epithelial cells. In these experiments, conditioned media obtained from heterotypic cultures were able to stimulate MMP9 production in epithelial cells, suggesting that critical paracrine factors were being secreted after the establishment of direct heterotypic cell–cell contacts. Using a PCR array, we show that IL1β acts as a galectin-3-induced paracrine signal in fibroblasts. Finally, we show in vivo that removal of the basement membrane mediates galectin-3-induced IL1β signaling in the stoma with concomitant MMP9 production in wounded corneas. These effects were not observed in the galectin-3 null mice.
Conclusions :
Overall, these data support the concept that epithelial galectin-3 modifies the proteolytic microenvironment in a paracrine manner by promoting IL1β secretion in fibroblasts.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.