Abstract
Purpose:
Recent data suggest that galectin-3 can both promote and repress an inflammatory response in macrophage and neutrophils by interacting with lipopolysaccharide (LPS). The goal of this study was to determine whether galectin-3 mediates the LPS response in immortalized human corneal-limbal (HCLE) and conjunctival (HCjE) epithelial cells.
Methods:
HCLE and HCjE cells were stratified and treated with LPS for 24 hours. Galectin-3 expression was abrogated using siRNA (si-Gal3). Control cells were transfected with a siRNA scramble sequence (si-Scramble). Knockdown of galectin-3 was verified by western blot analysis. For rescue experiments, galectin-3 knockdown cells were treated with conditioned media from scramble cells supplemented with LPS. Interleukin 8 (IL-8) protein levels were monitored by western blot analysis. MMP9 secretion was determined by gel zymography.
Results:
Abrogation of galectin-3 expression by siRNA in HCLE and HCjE cells decreased galectin-3 protein levels by 90%. In both cell lines, LPS induced an increase of IL-8 and MMP9 secretion. IL-8 secretion was significantly reduced in si-Gal3 HCLE and HCjE cells compared to si-Scramble. Similarly, the level of MMP9 was decreased in si-Gal3 HCLE and HCjE cells compared to si-Scramble. The secretion levels of IL-8 and MMP9 in galectin-3 knockdown cells returned to normal in the presence of conditioned media.
Conclusions:
Secreted galectin-3 mediates the response of corneal and conjunctival epithelial cells to LPS, creating a potential therapeutic target for ocular surface inflammation.