Correspondence to Creydt VP et al., Cytotoxic effect of Shiga toxin-2 holotoxin and its B subunit on human renal tubular epithelial cells, Microbes Infect. 8(2) (2006) 410-419

摘要

Ibarra et al. reported a cytotoxic effect of Shiga toxin-2 (STx2) holotoxin and its B-subunit (STx2B) on human renal tubular epithelial cells. At the end of their study, the authors conclude on a potential risk of the use of STx2B as a component in an acellular Shiga toxin-producing E. coli (STEC) vaccine, or as an antigen carrier for cancer vaccines.Although the toxic effects of the STx2 holotoxin are clearly demonstrated in the study by Ibarra and were expected from previous studies, the role of STx2B in the induction of renal tubular epithelial cell cytotoxicity is novel, but less convincing. Indeed, STx2B has a weak activity on survival of HRTEC cells, and 1000-fold higher doses of STx2B were required to reduce cell survival to the same levels as those observed after treatment with STx2 holotoxin. This effect of STx2B on survival was only found after 72 h of culture, and at high protein concentrations. In addition, HRTEC incubated with high-dose STx2B (10 mug/ml) for 48 h never showed inhibition ofprotein synthesis exceeding 20%. Reversal of STx2B activity by an anti-STx2B antibody was only performed after 24 h of incubation of HRTEC with STx2B when the effect on viability was weak (viability at 85 +- 3% of control levels). This control would have been more relevant if it had been performed at 72 h with high concentrations of STx2B.