Synergistic Cytotoxicity of Vibrio cholerae O1 El Tor Hemolysin and Live Vibrios to Human Intestinal Cells in vitro

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We studied the synergistic cytotoxicity of E1 Tor hemolysin (ETH, molecular mass ; 65 kDa) produced byVibrio choleraeO1 and live vibrios, such as classical 569B, E1 Tor N86, or Bengal O139 strain, to Intestine 407 cells of a human cell line. When Intestine 407 cells were incubated with live E1 Tor N86in vitro, the viability of Intestine 407 cells decreased, whereas the viability of Intestine 407 cells incubated with a classical 569B or Bengal O139 (106cfu/ml) did not change. This finding suggests that live N86 are cytotoxic to Intestine 407 cells. We, however, detected cytotoxicity to Intestine 407 cells by live 569B, N86, or 0139 at 106cfu/ml in the presence of a non-toxic dose of ETH (10 ng/ml) . The synergistic cytotoxicity by both ETH and live 569B was inhibited by dextran 4 with a molecular mass of 4 to 6 kDa. This result suggests that the pore formed by ETH may be required for synergistic cytotoxicity. The culture supernatant of 569B enhanced the cytotoxicity of ETH. Synergistic cytotoxicity was diminished by treatment of the culture supernatant with 0.4 % formalin or heating at 100°C or 56°C. These results imply that the proteineous factor (s) which cooperates with ETH is secreted by live 569B. Our findings of synergistic cytotoxicity by both live vibrio and ETH to human intestinal cells may contribute to the understanding of the pathogenesis of cholera, especially the role of ETH as a virulence factor.
昭和大学・昭和医学会の論文