Immunohistochemical localization of transforming growth factor-beta 1, -beta 2, and -beta 3 latency-associated peptide in human cornea.

PURPOSE: To study spatial distribution of TGF-beta isoforms (TGF-beta 1, -beta 2, and -beta 3) in the human cornea and to elucidate their biologic roles in corneal maintenance.
METHODS: Frozen sections obtained from eight human autopsy eyes were placed on gelatin-coated slides. After blocking of nonspecific binding sites, the slides were incubated with rabbit polyclonal antibody to the latency-associated peptide (LAP) region of human TGF-beta 1, TGF-beta 2, and TGF-beta 3 precursors, followed by the incubation with biotinylated swine anti-rabbit IgG. Subsequently, a streptavidin-labeled alkaline phosphatase technique was used.
RESULTS: In the corneal region, beta 1-LAP antibody did not stain either epithelium or stroma, beta 2-LAP antibody stained all epithelial cell layers and the corneal stroma, and beta 3-LAP antibody stained the subepithelial region alone. The staining pattern in the limbal region was almost the same as in the corneal region, except in the limbal stroma, which was stained with beta 1-LAP antibody in three of eight samples. In the trabecular meshwork, all samples showed clear staining with beta 2-LAP antibody, whereas beta 1-LAP and beta 2-LAP antibody stained faintly in five of eight and four of eight samples, respectively.
CONCLUSION: beta 2-LAP was found in the corneal epithelium and stroma and beta 3-LAP in the subepithelial region, suggesting that TGF-beta 2 and TGF-beta 3 may play essential roles in normal corneal epithelial maintenance in vivo.