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Lysosomal involvement in cellular intoxication with Clostridium difficile toxin B.
1Department of Bacteriology, Karolinska institutet, Stockholm, Sweden.
Microbial Pathogenesis
|August 1, 1986
Summary
Clostridium difficile toxin B requires endosomal acidification, lysosomal fusion, and protease activation for cellular intoxication. Inhibiting these steps prevents toxin-induced effects, offering insights into cellular entry mechanisms.
Area of Science:
- Cell Biology
- Microbiology
- Toxicology
Background:
- Clostridium difficile toxin B causes cell damage through internalization.
- Understanding the precise mechanism of toxin B entry into cells is crucial for developing countermeasures.
Purpose of the Study:
- To elucidate the fate of endocytosed Clostridium difficile toxin B.
- To identify the specific cellular processes required for toxin B-mediated cellular intoxication.
Main Methods:
- Investigated toxin B internalization in human lung fibroblasts under various conditions (temperature, chemical inhibitors).
- Utilized Chinese hamster ovary cell mutants defective in endosomal acidification.
- Assessed the role of lysosomal proteases using specific inhibitors.
Main Results:
- Toxin B intoxication was inhibited by preventing endosome-lysosome fusion (low temperature, high KCl, benzyl alcohol).
- Lysosomal protease inhibitors blocked toxin B effects, indicating a requirement for protease activity.
- Mutant cells resistant to toxin B highlighted the necessity of endosomal acidification.
Conclusions:
- Cellular intoxication by Clostridium difficile toxin B necessitates endosomal acidification, fusion with lysosomes, and subsequent processing by lysosomal proteases.
- Low pH exposure is essential but insufficient; fusion and protease activity are also critical for toxin entry into the cytosol.