[Proteases of the elastase type].

Elastin in the most resistant fibrous protein of the organisms. Its degradation is catalysed by proteases designated as elastases. Elastic fibers appeared during phylogenesis at the level of the first Vertebrates and rendered possible the emergence of efficient circulatory and respiratory systems which were necessary for the development of the higher Vertebrates. Several pathological conditions, mostly age-dependent, are accompanied by the degradation of elastic fibers or their alteration due to increasing association with lipids and calcium salts. Several proteases (endopeptidases) of cellular origin were described over the last years, especially those of PMN leukocytes, platelets, monocytes-macrophages, smooth muscle cells and fibroblasts. Although less active on fibrous elastin than pancreatic elastase, these enzymes may well play an important role in the development of age-dependent pathologies such as athero-arteriosclerosis and emphysema. The involvement of cellular elastases in these pathologies is discussed in some detail. The age-dependent increase, both in vivo and in vitro of the elastase activity of fibroblasts and smooth muscle cells appears to play an important role in the modifications of cell behaviour observed in the above pathologies.