Accumulation of latent transforming growth factor-β binding protein-1 and TGFβ1 in extracellular matrix of filtering bleb and of cultured human subconjunctival fibroblasts

Abstract.

Purpose: To examine immunohistochemically whether extracellular matrix (ECM) of the filtering bleb and of cultured human subconjunctival fibroblasts contains latent TGFβ binding protein-1 (LTBP-1) and TGFβ. Methods: An enucleated human eye that had undergone trabeculectomy and cultured human subconjunctival fibroblasts were processed for light microscopic immunohistochemistry. Antibodies against LTBP-1, collagen types, fibrillin-1 and TGFβs were used. TGFβ1 was located by detecting β1-latency associated peptide (LAP). Results: LTBP-1, β1-LAP and fibrillin-1 were all located in the subepithelial ECM as well as in the basal epithelial cells of the conjunctiva over the filtering bleb. TGFβ2 and β3 were immunolocated to epithelium and/or fibroblasts/keratocytes. ECM deposited in confluent fibroblast cultures was positive for β1-LAP, LTBP-1 and fibrillin-1, whereas sparse cells were negative. Conclusions: LTBP-1, β1-LAP and fibrillin-1 are co-localized to the ECM of the filtering bleb and of cultured conjunctival fibroblasts. Both conjunctival epithelium and fibroblasts are considered to be the source of TGFβ in healing bleb. ECM secreted by in vivo and in vitro subconjunctival fibroblasts may works as a scavenger or repository of TGFβ.