Proteinases from invasive larvae of the trematode parasite Schistosoma mansoni degrade connective-tissue and basement-membrane macromolecules.

Larvae of the human parasite Schistosoma mansoni, which invade the vascular system through the skin, secrete proteinases that degrade radioactively labeled extracellular matrices produced by smooth-muscle cells, dermal fibroblasts and endothelial cells. The proteinase purified from one larval form, the cercaria, degrades fibronectin and laminin and is a type-specific collagenase with activity against basement-membrane collagens IV and VIII, but not interstitial collagens I, III and V. The substrate specificity of this enzyme resembles that of the proteolytic enzymes which facilitate tissue invasion by inflammatory cells and tumour cells.