HUMAN MAST-CELL CHYMASE AND LEUKOCYTE ELASTASE RELEASE LATENT TRANSFORMING GROWTH FACTOR-B1 FROM THE EXTRACELLULAR-MATRIX OF CULTURED HUMANEPITHELIAL AND ENDOTHELIAL-CELLS

Monolayer cultures of human epithelial and endothelial cells were used to study the association of latent transforming growth factor-beta 1 (TGF-beta 1) to extracellular matrices and its release and activation during matrix degradation, Human umbilical vein endothelial cells and embryonic lung fibroblasts produced relatively high revels of TGF-beta 1, its propeptide (beta 1-latency-associated protein), and latent TGF -beta-binding protein and incorporated latent TGF-beta 1 into their ma trices as shown by immunoblotting, Amnion epithelial cells produced lo wer levels of these proteins, Confluent cultures of epithelial cells w ere exposed to matrix-degrading proteases and glycosidases, Mast cell chymase, leukocyte elastase, and plasmin efficiently released matrix-b ound latent TGF-beta 1 complexes, while chondroitinase ABC and heparit inases were ineffective, The ability of the proteases to activate reco mbinant latent TGF-beta 1 was tested using growth inhibition assays an d a novel sodium deoxycholate-polyacrylamide gel electrophoresis follo wed by immunoblotting. Sodium deoxycholate solubilized M(r) 25,000 TGF -beta 1 but did not dissociate high M(r) latent TGF-beta 1 complexes, allowing separation of these forms by polyacrylamide gel electrophores is, Mast cell chymase and leukocyte elastase did not activate latent T GF-beta 1, suggesting that its release from matrix and activation are controlled by different mechanisms. The release of TGF-beta from the m atrix by leukocyte and mast cell enzymes may contribute to the accumul ation of connective tissue in inflammation.