Pino-Heiss S, Brown M, McKerrow J H
Exp Parasitol. 1985 Apr;59(2):217-21. doi: 10.1016/0014-4894(85)90075-x.
A radioactively labeled in vitro model of the extracellular matrix of the mammalian intestinal wall and of snail tissue was used to determine whether proteolytic enzymes released by eggs and miracidia of Schistosoma mansoni could degrade connective tissue macromolecules in the type of interactive framework found in vivo. Eggs were collected and miracidia hatched in the presence of antibiotics to eliminate bacterial contamination. Uninfected livers were used as controls to ensure that the tissue dissociation and egg collection procedures did not produce proteolytic activity. One thousand live eggs incubated with the extracellular matrix for 72 hr at 37 C degraded 31% of the glycoprotein in the matrix; there was no degradation of elastin or collagen. Medium conditioned by incubation with eggs degraded 60% as much of the matrix as the live eggs themselves. The proteolytic activity of the egg-conditioned medium was greater in the presence of dithiothreitol. Miracidia incubated with the extracellular matrix in tissue culture medium at 27 or 37 C rapidly transformed to living sporocysts. This transformation was accompanied by a release of proteolytic activity, resulting in the degradation of 49 to 58% of the glycoprotein in the extracellular matrix by 1000 miracidia. Again, no elastin or collagen was degraded. The time course of degradation by miracidia was rapid over 24 hr and thus similar to that previously reported for cercariae. Degradation by eggs occurred more slowly over 72 hr. These data confirm that both eggs and miracidia secrete proteinases which are capable of degrading at least the glycoprotein components of extracellular matrix to facilitate their migration through intestinal wall or penetration of snail tissue.
使用哺乳动物肠壁和蜗牛组织细胞外基质的放射性标记体外模型，以确定曼氏血吸虫卵和毛蚴释放的蛋白水解酶是否能够降解体内发现的相互作用框架类型中的结缔组织大分子。收集卵并在抗生素存在下孵育毛蚴以消除细菌污染。使用未感染的肝脏作为对照，以确保组织解离和卵收集程序不会产生蛋白水解活性。将1000个活卵与细胞外基质在37℃下孵育72小时，可降解基质中31%的糖蛋白；弹性蛋白或胶原蛋白未被降解。与卵孵育的条件培养基降解的基质量是活卵本身的60%。在二硫苏糖醇存在下，卵条件培养基的蛋白水解活性更高。在组织培养基中于27℃或37℃与细胞外基质孵育的毛蚴迅速转化为活的子孢蚴。这种转化伴随着蛋白水解活性的释放，导致1000个毛蚴降解细胞外基质中49%至58%的糖蛋白。同样，弹性蛋白或胶原蛋白未被降解。毛蚴降解的时间进程在24小时内很快，因此与先前报道的尾蚴相似。卵的降解在72小时内发生得较慢。这些数据证实，卵和毛蚴都分泌蛋白酶，这些蛋白酶能够至少降解细胞外基质的糖蛋白成分，以促进它们穿过肠壁或穿透蜗牛组织。
