Modulation of growth factor binding properties of alpha 2-macroglobulin byenzyme therapy

Purpose: To investigate the binding of transforming growth factor-beta (TGF -beta) to human alpha2-macroglobulin upon oral treatment of patients with p roteases. Methods: Volunteers were given a cocktail of active proteinases ( Phlogenzym) composed of trypsin, bromelain and the additive rutoside orally over a period of 7 days at low dose followed by a bolus application. Befor e and after medication plasma was immediately withdrawn and binding of I-12 5-TGF-beta to the proteinase inhibitor alpha2-macroglobulin was determined by electrophoresis and gamma -counting. Cell culture experiments were perfo rmed to study the effect of transformed alpha2-macroglobulin on TGF-beta -s timulated proliferation of skin fibroblasts. Results: Ingestion of proteina ses was found to trigger the formation of intermediate forms of alpha2-macr oglobulin displaying high affinity to TGF-beta. Maximum binding of TGF-beta was observed 1-2 h after bolus ingestion, and steadily levelled off with t ime. In vitro experiments demonstrated that complex formation of diverse pr oteinases (trypsin, alpha -chymotrypsin, bromelain and plasmin) with alpha2 -macroglobulin conferred binding of I-125-TGF-beta. alpha2-Macroglobulin tr ansformed by methylamine or proteinases was found to abolish the TGF-beta e ffect on fibroblasts in cell culture. Conclusions: Intestinal absorption of proteinases triggers the formation of TGF-beta binding species of alpha2-m acroglobulin in blood. Mediated by this process high concentrations of TGF- beta might be reduced via enhanced clearance of alpha2-macroglobulin-TGF-be ta complexes. Thus, proteinase therapy may have beneficial effects in treat ment of fibrosis and certain cancers accompanied by excessively high TGF-be ta concentrations.