A CORNEAL EPITHELIAL INHIBITOR OF STROMAL CELL COLLAGENASE SYNTHESIS IDENTIFIED AS TGF-BETA-2

Citation
Kj. Strissel et al., A CORNEAL EPITHELIAL INHIBITOR OF STROMAL CELL COLLAGENASE SYNTHESIS IDENTIFIED AS TGF-BETA-2, Investigative ophthalmology & visual science, 36(1), 1995, pp. 151-162
Citations number
57
Categorie Soggetti
Ophthalmology
ISSN journal
01460404
Volume
36
Issue
1
Year of publication
1995
Pages
151 - 162
Database
ISI
SICI code
0146-0404(1995)36:1<151:ACEIOS>2.0.ZU;2-L
Abstract
Purpose. To determine the molecular mechanisms whereby substances rele ased by corneal epithelial cells act to inhibit the elaboration of col lagenolytic activity by corneal stromal cells and to determine whether inhibitory activity might be mediated by interleukin-1 receptor antag onist (IL-1ra) or transforming growth factor (TGF)-beta. Methods. Cond itioned media were generated from primary cultures of rabbit corneal e pithelial cells, from passaged cultures of rabbit corneal stromal fibr oblasts, and from cells of the rabbit corneal epithelial cell, line, S IRC. Pure populations of stromal cells were isolated from rabbit corne a and used directly for bioassay of the conditioned media to detect su bstances that inhibit collagenase synthesis. The mink lung epithelial cell line, Mv1Lu, was used for bioassay of TGF-beta-like activity. The addition of specific neutralizing antisera to bioassays allowed an as sessment of the contribution of each isoform to the net regulatory act ivity. Reverse transcription-polymerase chain reaction and Northern bl ot analysis were employed to detect the presence of IL-1ra or TGF-beta mRNA species in cells from cultures used to generate conditioned medi a. Results. Both stimulatory and inhibitory substances that regulate t he synthesis of stromal cell collagenase are released by corneal epith elial cells in primary culture. In contrast, only stimulatory activity is produced by corneal fibroblasts or SIRCs. MRNAs for a TGF-beta iso form, TGF-beta 2, and IL-1ra were identified in epithelial cells. Stro mal fibroblasts also expressed TGF-beta 2 mRNA, but no evidence was fo und for expression of TGF-beta 3 mRNA in any of the three cell types. TGF-beta 2 is released by epithelial cells in both active and latent f orms. This cytokine mediates the major portion of the net inhibitory a ctivity against stromal cell collagenase synthesis produced by corneal epithelial cells. Conclusions. This study demonstrates the expression of TGF-beta 2 and IL-1ra by corneal epithelial cells in culture. It i s the TGF-beta 2 that acts as the major inhibitor of collagenase synth esis by corneal stromal cells in culture. However, IL-1ra and TGF-beta 2 are likely to play important roles in epithelial-mesenchymal intera ctions regulating corneal development, homeostatic maintenance, and re pair.