Fatal hemorrhage induced by subtilase cytotoxin from Shiga-toxigenic Escherichia coli

Abstract

Subtilase cytotoxin (SubAB) is an AB5 type toxin produced by a subset of Shiga-toxigenic Escherichia coli. The A subunit is a subtilase-like serine protease and cleaves an endoplasmic reticulum chaperone BiP. The B subunit binds to a receptor on the cell surface. Although SubAB is lethal for mice, the cause of death is not clear. In this study, we demonstrate in mice that SubAB induced small bowel hemorrhage and a coagulopathy characterized by thrombocytopenia, prolonged prothrombin time and activated partial thromboplastin time. SubAB also induced inflammatory changes in the small intestine as detected by 18F-Fluoro-2-deoxy-D-glucose positron emission tomography imaging and histochemical analysis. Using RT-PCR and ELISA, SubAB was shown to increase interleukin-6 in a time-dependent manner. Thus, our results indicate that death in SubAB-treated mice may be associated with severe inflammatory response and hemorrhage of the small intestine, accompanied by coagulopathy and IL6 production.

Differential Effects of Escherichia coli Subtilase Cytotoxin and Shiga Toxin 2 on Chemokine and Proinflammatory Cytokine Expression in Human Macrophage, Colonic Epithelial, and Brain Microvascular Endothelial Cell Lines

“…To the best of our knowledge, there are no published reports of cytokine profiles for patients with HUS caused by SubAB-expressing STEC strains. Furukawa et al (34) reported elevated IL-6 expression in intestinal tissue of mice after intraperitoneal injection of purified SubAB, and this was associated with fatal hemorrhage. They did not observe changes in expression of any of the other cytokines tested (IL-1, IL-4, IL-10, IL-12, IL-17, IL-22, gamma interferon, TNF-␣, or granulocyte-macrophage colony-stimulating factor [GM-CSF]).…”

Recent Advances in Understanding Enteric Pathogenic Escherichia coli

“…In Vero cell assays, recombinant SubAB was found to be more toxic than Stx1 or Stx2 (343). Pure SubAB given to mice is lethal and causes hemorrhaging in the small intestine and a disease similar to HUS, including renal damage, thrombotic microangiopathy, intestinal hemorrhages, hemolytic anemia, and thrombocytopenia (346,347). Damage was also seen in different organs, such as the liver, spleen, and brain (347), and has been reported to cause leukocytosis (348).…”

Subtilase Cytotoxin Enhances Escherichia coli Survival in Macrophages by Suppression of Nitric Oxide Production through the Inhibition of NF-κB Activation

“…Total RNA was measured, and 1 to 5 g were reverse transcribed using Ready-To-Go You-Prime first-strand beads (GE Healthcare) with oligo(dT) [12][13][14][15][16][17][18] primer (Invitrogen). cDNA content was measured by real-time PCR with SYBR green reagent using an ABI PRISM 7300 sequence detection system (Applied Biosystems, Foster City, CA).…”

“…Specific primers used for real-time PCR were as follows: mouse iNOS forward, 5=-GTTCTCAGCCCAACAA TACAAGA-3=, and reverse, 5=-GTGGACGGGTCGATGTCAC-3=. Primers for GAPDH cDNA amplification were as described previously (13).…”