Uptake pathways of clinical and healthy animal isolates of Campylobacter jejuni into INT-407 cells

Abstract

Campylobacter jejuni isolates obtained from human and animal sources showed different invasion levels into human embryonic intestinal (INT-407) cells. There was no significant relation between the degree of invasion and cytotoxins production. The depolymerization of both microfilaments by cytochalasin-D and microtubules by colchicine, demecolcine and nocodazole or stabilization of microtubules by paclitaxel reduced the invasiveness of C. jejuni, although microfilament depolymerization showed greater inhibition than microtubule depolymerization. Interference with receptor-mediated endocytosis by G-strophanthin and monodansylcadaverine and inhibition of endosome acidification by monensin reduced the number of viable intracellular C. jejuni cells. Furthermore inhibition of only host protein kinases by staurosporine, but not phosphoinositide 3-kinase by wortmannin or protein kinase-C by calphostin-C, significantly reduced invasion of epithelial cells by C. jejuni. These data suggest that the internalization mechanism triggered by C. jejuni is strikingly different from the microfilament-dependent invasion mechanism exhibited by many of the well-studied enteric bacteria such as enteroinvasive strains of Escherichia coli, Salmonella typhimurium, Shigella flexneri, Yersinia enterocolitica and Yersinia pseudotuberculosis.