Degradation of extracellular matrix by larvae of Schistosoma mansoni. I. Degradation by cercariae as a model for initial parasite invasion of host
McKerrow, J.H.; Keene, W.E.; Jeong, K.H.; Werb, Z.
Laboratory Investigation; A Journal of Technical Methods and Pathology 49(2): 195-200
1983
ISSN/ISBN: 0023-6837 PMID: 6876746 Document Number: 216977
The ability of S. mansoni cercariae to degrade a model extracellular connective tissue matrix produced by rat vascular smooth muscle cells in culture was studied. Cercariae were stimulated to degrade the matrix by skin lipid or linoleic acid. At the maximally stimulating concentration of linoleic acid (25 micro g/cmsuperscript 2), 68% of the total matrix was degraded, including 57% of the glycoprotein, 79% of the elastin and 8% of the collagen. Degradation of the matrix and transformation of cercariae to schistosomula began within minutes of exposure to maximally stimulating concentrations of linoleic acid. Degradation continued for 24 h and was dependent on the number of cercariae. Some degradation occurred without exogenous stimulants, but at a slower rate than with skin lipid or linoleic acid. Degradation of matrix was inhibited by alpha 1-proteinase inhibitor and soyabean trypsin inhibitor. EDTA inhibited degradation by unstimulated but not linoleic acid-stimulated cercariae. Preacetabular gland secretions collected from cercariae also degraded the matrix with an activity 86% of that of live cercariae. Preacetabular gland proteolytic activity was also inhibited by alpha 1-proteinase inhibitor, soyabean trypsin inhibitor and EDTA. The similar characteristics of matrix degradation by both live cercariae and cercarial preacetabular gland secretions support the idea that a proteinase secreted by cercarial preacetabular glands facilitates invasion of skin and connective tissue by these larvae.