Human microvascular endothelial cells resist Shiga toxins by IFN-gamma treatment in vitro.
Shiga toxins (Stxs) produced by enterohaemorrhagic Escherichia coli or Shigella dysenteriae damage human endothelial cells predominantly in cooperation with pro-inflammatory cytokines, such as TNF-alpha. However, in this study, in vitro IFN-gamma pre-treatment resulted in human lung microvascular endothelial cells becoming over 10,000-fold less sensitive to Stxs. In contrast, in their basal condition, they were extremely sensitive to Stxs. Interestingly, TNF-alpha addition to IFN-gamma reverted the Stx-resistant phenotype, which corresponded with its well-established enhancing effect on Stx toxicity. Toxin binding to the cell was barely affected by IFN-gamma. Also, the toxin uptake in the Stx-resistant phenotype was more than 100-fold greater than that of normal cells, when compared at Stx concentrations resulting in equivalent degrees of cell damage. Protein synthesis was inhibited by nearly 90% in the Stx-resistant phenotype after 24 h toxin exposure. This indicated that the intracellular toxin was active as an N-glycosidase, while cells were still over 60% viable, suggesting a possible unknown cytotoxic function of Stx. In conclusion, this study shows a unique effect of IFN-gamma in the suppression of the toxicity of Stxs in a human microvascular endothelial cell model and the involvement of a novel mechanism in this suppression.
Yoshida
Tomoaki
T
Department of Microbiology and Immunology, School of Medicine, Aichi Medical University, Yazako, Nagakute, 480-1195 Aichi, Japan.
Sugiyama
Tsuyoshi
T
Department of Microbiology and Immunology, School of Medicine, Aichi Medical University, Yazako, Nagakute, 480-1195 Aichi, Japan.
Koide
Naoki
N
Department of Microbiology and Immunology, School of Medicine, Aichi Medical University, Yazako, Nagakute, 480-1195 Aichi, Japan.
Mori
Isamu
I
Department of Microbiology and Immunology, School of Medicine, Aichi Medical University, Yazako, Nagakute, 480-1195 Aichi, Japan.
Yokochi
Takashi
T
Department of Microbiology and Immunology, School of Medicine, Aichi Medical University, Yazako, Nagakute, 480-1195 Aichi, Japan.
D018929:Cell Culture Techniques; D004347:Drug Interactions; D004351:Drug Resistance; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D006801:Humans; D020382:Interleukin-18 / Q000494:pharmacology*; D022603:Shiga Toxins / Q000633:toxicity*
D020382:Interleukin-18; D022603:Shiga Toxins