Characterization of elastase associated with granulomatous tissue remodeling.

Elastases have been reported to be involved in various types of tissue injury. In this study we detected hydrolytic activities for [3H]-elastin and Suc-Ala-Ala-Ala-pNA (SLAPN) in hepatic granulomas which became elevated in parallel with enlargement of the granulomas and disappearance of aldehyde-fuchsin-stained filaments in the lesions of mice infected with Schistosoma mansoni. The elastase was partially purified by gel filtration followed by anion-exchange chromatography. This enzyme has a molecular weight of 20-25k and hydrolyzed denatured collagen (azocoll), Glu-Pro-Val-pNA, SLAPN, and [3H]-elastin. Optimal pH was 7-8.5. It is a serine proteinase and distinct in its inhibitor profile from murine peritoneal macrophage elastase, which has been reported by others. Digestion of elastic fibers in vessel walls and fine fibrils in newly developed granulomas by the granuloma elastase was histochemically identified with aldehyde-fuchsin stain. These results indicate that a serine proteinase functions as a major elastase in granulomatous tissue remodeling and may account for the disappearance of elastic fibers and other elements of the matrix in fully developed granulomas.