THE PATHOGENIC MECHANISMS OF SHIGA TOXIN AND THE SHIGA-LIKE TOXINS

It is now well documented that some enteric bacteria which cause diarrhoeal and/or dysenteric disease produce, at high levels, one or more of a family of protein toxins referred to as Shiga toxin and Shiga-like toxins (SLTs; alternatively called verocytotoxins or VTs). Within the past few years, there have been considerable advancements made in our understanding of the biochemistry and molecular biology of Shiga toxin and SLTs. However, the precise role of the toxins in mediating colonic disease, as well as their contribution to the development of extra-intestinal sequelae (e.g. the haemolytic uraemic syndrome and neurological disorders), remain less clear. In this MicroReview, we will briefly summarize recent progress in Shiga toxin- and SLT-related research and present evidence supporting the concept that these toxins contribute to pathogenesis by directly damaging vascular endothelial cells, thereby disrupting the homeostatic properties of these cells. We will also discuss data which suggest that toxin-mediated damage in the kidney may not be limited to glomerular endothelial cells but may include tubular epithelial cells. Thus, the role of the toxins in renal disease may not be limited to the glomeruli, as was initially hypothesized when the association of infection with toxin-producing strains and the development of acute renal failure was established.