ABSTRACT
PURPOSE: To determine whether glucocorticoids suppress corneal lymphatic vessel growth (lymphangiogenesis) or induce lymphatic vessel regression. METHODS: We measured human lymphatic endothelial cell proliferation and collagen-induced tubulogenesis in culture conditions with and without dexamethasone, a potent glucocorticoid. We developed a modification of the mouse corneal suture model that allowed us to visualize lymphatic vessel growth (with suture) or regression (suture removed) using immunofluorescence and microscopic techniques. We administered dexamethasone or vehicle control to mice with sutured corneas. We visualized and quantified the corneal lymphatic vessels. We measured vascular endothelial growth factor-C and tumor necrosis factor-α messenger RNA expression in unsutured or sutured corneas using quantitative reverse transcriptase-polymerase chain reaction. RESULTS: High-dose dexamethasone did not change the proliferation or tubulogenesis properties of human lymphatic endothelial cells in vitro. We demonstrated suppressed corneal lymphatic vessel growth rather than lymphatic vessel regression in mice treated with dexamethasone. Expressions of corneal vascular endothelial growth factor-C and tumor necrosis factor-α messenger RNA were similar in mice treated with or without dexamethasone. CONCLUSIONS: Dexamethasone suppressed new lymphatic vessel growth and did not induce lymphatic vessel regression. These findings identify a novel mechanism of glucocorticoid action: suppression of corneal lymphangiogenesis.
Subject(s)
Endothelial Cells/drug effects , Endothelium, Corneal/drug effects , Endothelium, Vascular/drug effects , Glucocorticoids/pharmacology , Lymphangiogenesis/drug effects , Animals , Cells, Cultured , Dexamethasone/pharmacology , Endothelium, Corneal/cytology , Endothelium, Corneal/metabolism , Endothelium, Vascular/cytology , Endothelium, Vascular/metabolism , Humans , Mice , Models, Animal , Reverse Transcriptase Polymerase Chain Reaction , Tumor Necrosis Factor-alpha/metabolism , Vascular Endothelial Growth Factor C/metabolismABSTRACT
Lymphatic vessel growth requires extensive remodeling of the extracellular matrix, a process hypothesized to be related to the expression and function of the matrix metalloproteinases. We used a protein based screening strategy to demonstrate increased matrix matalloproteinase-10 expression in human lymphatic endothelial cells undergoing collagen I induced tubulogenesis. Knock-down experiments showed that matrix metalloproteinase-10 regulated lymphatic endothelial cell tubulogenesis. ß1 integrin signaling via the ERK/MAPK pathway increased matrix metalloproteinase-10 mRNA and protein expression in human lymphatic endothelial cells. These findings demonstrate a novel mechanism by which ß1 integrin regulates matrix metalloproteinase-10 expression during lymphatic vessel remodeling.