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Effect of Shiga toxins on granulocyte function.
1Department of Food and Health Science, Faculty of Human Life Science, Jissen Women's University, Tokyo, Japan. yaoki@univ.jissen.ac.jp
Microbial Pathogenesis
|July 26, 2002
Summary
Shiga toxin 2 (Stx 2) significantly increases granulocyte count and medullasin activity in mice, contributing to tissue injury. This toxin impairs granulocyte bactericidal function, exacerbating E. coli infections like hemolytic uremic syndrome.
Area of Science:
- Microbiology
- Immunology
- Toxicology
Background:
- Shiga toxin (Stx) 2 injection in mice causes severe peripheral blood granulocytosis.
- Granulocyte function changes following Stx 2 exposure require further clarification.
Purpose of the Study:
- To elucidate the impact of Shiga toxin 2 on granulocyte function.
- To investigate the role of medullasin and superoxide production in Stx 2-induced toxicity.
Main Methods:
- Intraperitoneal injection of Stx 1 and Stx 2 into mice.
- Measurement of granulocyte count, medullasin activity, Cathepsin G levels, and superoxide production in granulocytes.
- In vitro assessment of Stx 1 and Stx 2 effects on human granulocytes.
Main Results:
- Stx 2 significantly increased mouse granulocyte count and medullasin activity.
- Stx 1 did not elevate granulocyte count or medullasin activity.
- Stx 2-exposed granulocytes showed reduced superoxide production; both Stx 1 and Stx 2 decreased human granulocyte superoxide activity in vitro.
- Cathepsin G levels increased only slightly after Stx 2 injection.
Conclusions:
- Shiga toxins augment bacterial virulence by reducing granulocyte bactericidal activity.
- Tissue injury from Shiga toxin-producing E. coli is primarily due to elevated granulocyte proteases like medullasin.
- Medullasin elevation contributes to hemolytic uremic syndrome pathogenesis.