Griffiths J K, Moore R, Dooley S, Keusch G T, Tzipori S
Department of Comparative Medicine, Tufts University School of Veterinary Medicine, North Grafton, Massachusetts 01536.
Infect Immun. 1994 Oct;62(10):4506-14. doi: 10.1128/iai.62.10.4506-4514.1994.
Caco-2 cells were grown on permeable filters and infected with Cryptosporidium parvum. Infection rates exceeded 50% of target cells with a sufficient inoculum dose of parasites. Infection induced a dose- and time-dependent fall in transmonolayer resistance, which was closely related to both the inoculum dose and the number of parasites detected by immunofluorescence. Caco-2a, MDBK, and MDBK subclone F5D2 evidenced similar declines in resistance when grown and infected under similar circumstances. Caco-2 monolayers became permeable to molecules of < or = 1,000 Da but continued to remain impermeable to exogenously added, or endogenously produced, proteins of > or = 1,881 Da. We found that infected monolayers released up to 50% of the total cellular lactase dehydrogenase into apical media, but not basal media, and that the vital dye propidium iodide avidly stained infected cells, and often parasites, when added to the apical reservoir. Cryptosporidium infection of Caco-2 monolayers increases transmonolayer permeability, induces an apical cellular and monolayer defect, and causes cell death.
将Caco-2细胞接种于可渗透滤膜上，并用微小隐孢子虫进行感染。当接种足够剂量的寄生虫时，感染率超过目标细胞的50%。感染导致跨膜电阻呈剂量和时间依赖性下降，这与接种剂量以及通过免疫荧光检测到的寄生虫数量密切相关。在相似条件下培养并感染时，Caco-2a、MDBK和MDBK亚克隆F5D2的电阻也出现了类似下降。Caco-2单层细胞对分子量小于或等于10００Da的分子变得具有通透性，但对外源添加或内源性产生的分子量大于或等于1881Da的蛋白质仍保持不通透性。我们发现，受感染的单层细胞可将高达50%的总细胞乳糖脱氢酶释放到顶端培养基中，而非基底培养基中，并且当向顶端储液器中添加活性染料碘化丙啶时，它会强烈染色受感染的细胞，并且常常也会染色寄生虫。Caco-2单层细胞受到隐孢子虫感染后，跨膜通透性增加，导致顶端细胞和单层细胞出现缺陷，并引起细胞死亡。
