Chen X M, LaRusso N F
Division of Gastroenterology and Hepatology, Center for Basic Research in Digestive Diseases, Mayo Medical School, Clinic, and Foundation, Rochester, Minnesota 55905, USA.
Gastroenterology. 2000 Feb;118(2):368-79. doi: 10.1016/s0016-5085(00)70219-8.
BACKGROUND & AIMS: Although infection of the intestinal and biliary tracts by Cryptosporidium parvum is a major problem in patients with the acquired immunodeficiency syndrome, the specific microbial and host molecules involved in C. parvum infection are unknown. We tested the hypothesis that lectin-carbohydrate interactions and cytoskeleton reorganization are involved in the infection of biliary and intestinal epithelia by C. parvum.
In vitro models of cryptosporidial infection using human biliary and intestinal epithelial cell lines were used to assay C. parvum attachment and invasion.
Exposure of C. parvum sporozoites to the sugar, galactose-N-acetylgalactosamine (Gal/GalNAc), and to bovine mucin reduced C. parvum attachment to biliary and intestinal epithelia up to 70%. Preincubation of cell monolayers with either lectins specific to Gal/GalNAc, or glycosidases that specifically release Gal/GalNAc oligosaccharides from glycoproteins, decreased attachment up to 80%. Cytochalasin B and cytochalasin D, but not nocodazole, decreased invasion of cells by C. parvum up to 70% without affecting attachment. During cell invasion (but not attachment), confocal microscopy showed recruitment of actin (but not tubulin) in biliary and intestinal epithelia directly adjacent to C. parvum.
Gal/GalNAc epitopes of glycoproteins on the epithelial apical membrane and Gal/GalNAc-specific sporozoite surface lectins are involved in the mechanism(s) of C. parvum attachment to intestinal and biliary epithelial cells, and actin remodeling in host cells is required for C. parvum invasion.
尽管微小隐孢子虫感染肠道和胆道是获得性免疫缺陷综合征患者的一个主要问题，但参与微小隐孢子虫感染的特定微生物和宿主分子尚不清楚。我们检验了这样一个假说，即凝集素 - 碳水化合物相互作用和细胞骨架重组参与微小隐孢子虫对胆道和肠道上皮的感染。
使用人胆道和肠道上皮细胞系的隐孢子虫感染体外模型来检测微小隐孢子虫的附着和侵袭。
将微小隐孢子虫子孢子暴露于糖类半乳糖 - N - 乙酰半乳糖胺（Gal/GalNAc）和牛黏蛋白，可使微小隐孢子虫对胆道和肠道上皮的附着减少达70%。用对Gal/GalNAc特异的凝集素或能从糖蛋白上特异性释放Gal/GalNAc寡糖的糖苷酶预孵育细胞单层，可使附着减少达80%。细胞松弛素B和细胞松弛素D，但不是诺考达唑，可使微小隐孢子虫对细胞的侵袭减少达70%，而不影响附着。在细胞侵袭过程中（而非附着过程中），共聚焦显微镜显示在紧邻微小隐孢子虫的胆道和肠道上皮中募集了肌动蛋白（而非微管蛋白）。
上皮顶端膜上糖蛋白的Gal/GalNAc表位和Gal/GalNAc特异的子孢子表面凝集素参与微小隐孢子虫附着于肠道和胆道上皮细胞的机制，宿主细胞中的肌动蛋白重塑是微小隐孢子虫侵袭所必需的。
