Relationship between Gb3 Expression and Cytotoxicity of Shiga-like Toxin I

Lim, Suk-Hwan; Kim, Gi-Young; Kim, Hyung-Chun; Kim, Young-Hee; Son, Yong-Hae; Oh, Yang-Hyo; Park, Yeong-Min

Original Article

Journal of the Korean Pediatric Society 2003;46(2):143-153.
Published online February 15, 2003.

Relationship between Gb3 Expression and Cytotoxicity of Shiga-like Toxin I

Suk-Hwan Lim¹, Gi-Young Kim², Hyung-Chun Kim², Young-Hee Kim², Yong-Hae Son², Yang-Hyo Oh², Yeong-Min Park²

¹Department of Pediatrics, Chonnam National University Medical School, Kwangju, Korea
²Department of Microbiology and Immunology, Pusan National University College of Medicine, Pusan, Korea

Shiga-like Toxin I의 세포독성과 수용체 Gb3 발현과의 관계

임석환^¹^, 김기영^²^, 김형천^²^, 김영희^²^, 손용해^²^, 오양효^²^, 박영민^²

^¹전남대학교 의과대학 소아과학교실
^²부산대학교 의과대학 미생물학교실

Correspondence:
Yeong-Min Park, Email: immunpym@pusan.ac.kr

Abstract

Purpose
: Infection with Shiga-like toxin (SLT)-producing Escherichia coli, an emerging human pathogen found particularly in young children under 5 years of age, causes a spectrum of illnesses with high morbidity and mortality, ranging from diarrhea to hemorrhagic colitis and hemolytic uremic syndrome. Host mediators play an important role in the pathogenesis of SLT-I toxicity. The experiments described here were designed to investigate the effect of SLT-I on TNF-α production and to understand the effect of TNF-α on GB3 expression. We also further examine the relationship between the Gb3 level and the differential susceptibility of cells to the cytotoxic action of SLT-I.
Methods
: The effect of purified SLT-1 from E. coli O157 : H7 (ATCC 43890) on tumor necrosis factor-α (TNF-α) production in Raw264.7 cells was investigated. Many mediators regulate endothelial cell membrane expression of the glycolipid globotriaosyleramide (Gb3), which serves as the toxin receptor, suggesting that the host response to the toxin or other bacterial products may contribute to pathogenesis by regulating target cell sensitivity to the toxins. Therefore, the relationships between Gb3 expression and cytotoxicity against SLT-I on three types of cells were evaluated.
Results
: Detectable levels of TNF-α were produced as early as six hours after induction and continued to increase during 48 hours by SLT-I. It was also found that Vero cells and dendritic cells (DC2.4 cells) expressed high levels of Gb3, 83% and 68%, respectively, and that Raw264.7 cells had a low level of Gb3 (29%) and appeared refractory to cytotoxicity against SLT-I. Vero cells and DC2.4 cells expressing high levels of Gb3 were highly susceptible to SLT-I. Furthermore, macrophages showed a resistance to SLT-I cytotoxicity, despite the fact that Gb3 expression was enhanced.
Conclusion
: These results strongly suggest that the expression of Gb3 is necessary but not sufficient to confer sensitivity of macrophages to SLT-I and further underpin the important role of SLT- I and its Gb3 receptors in the pathogenesis of E. coli O157 infection.

Key Words: E. coli O157, Shiga-like toxin, tumor necrosis factor-α, glycolipid globotriaosyleramide